Progress in Microbes and Molecular Biology Review Article 1 Updates on the development of vaccines and therapeutic options against rabies Roshan Arjun Ananda1,2†, Hooi-Leng Ser1†, Vengadesh Letchumanan1* 1Novel Bacteria and Drug Discovery (NBDD) Research Group, Microbiome and Bioresource Research Strength (MBRS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia. 2Clinical School Johor Bahru, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Johor Bahru 80100, Malaysia. †These authors contributed equally in the writing. Abstract: Even though rabies has been claiming more than 50,000 deaths annually worldwide, it is considered as a vaccine- preventable viral disease. More than 95 % of the total human rabies cases are caused by dogs. During the initial stage of infection, affected individuals usually show weakess at the bitten extremities and the virus can ultimately travel to the brain causing neurological signs. In attenuated (inactivated) form, the currently in use vaccines have been recommended by WHO for the prevention (i.e. pre-exposure prophylaxis, PrEP) and treatment (i.e. post exposure prophylaxis, PEP) regime against the rabies virus (RABV). However, given that they normally require refrigeration and are costly, there have been discussions revolving around potential development of newer, safer and cheaper alternative that can perform better and more convenient than the ones that are currently in use. The current review aims to explore general characteristics of RABV before looking into potential candidates of vaccines that have been studied. Further studies on the pathogenic mechanism of RABV and therapeutic approaches are still required to prevent the deathly infection following clinical mani- festation. In sum, integrated interventional strategy emphasizing human health and animal health is essential and requires collaboration between health authorities and the public. Keywords: rabies; vaccines; treatment; development; therapeutic Received: 27th June 2020 Accepted: 28th July 2020 Published Online: 7th August 2020 Citation: Ananda RA, Ser H-L, Letchumanan V. Updates on the Development of Vaccines and Therapeutic Options against Rabies. Prog Microbes Mol Biol 2020; 3(1): a0000100. https://doi.org/10.36877/pmmb.a0000100 Introduction Rabies is one of the dangerous zoonotic diseases, claiming more than 50,000 deaths per year worldwide[1]. The “culprit” behind rabies is known as rabies virus (RABV) which can be transmitted by animals including bats, raccoons and foxes[1–3]. Still, dog-mediated rabies infection accounts for more than 95% of the total human rabies cases as the virus can replicate in salivary glands of infected dogs. As a results, RABV can be easily transmitted from affected dogs through bite wounds, licking of damaged skin, or direct mucosal contact[1,4]. The virus attaches itself to its cellular targets by its surface protein (i.e. RABV-G), rapidly gaining access to peripheral nerves. Via retrograde axonal transport and trans-synaptic spread, RABV ultimately enters the brain[5]. If the disease is not treated in a prompt manner, death can occur within 5–7 days upon onset of symptoms[6]. The incubation time before clinical manifestation is influenced by several variables including distance of injection site from the central nervous system (CNS) and virus load at the wound site[7]. Shorter incubation period was observed in victims with a wound on the head/neck or category III exposure[8].Commonly, initial presentation of rabies-infected victims is the weakness at the bitten extremities, which subse- quently progresses into acute neurological signs[6,9]. However, there are circumstances in which the victims presented unusual symptoms including severe abdominal pain and abnormal sexual behaviours[10,11]. Rabies infection can manifest as furious or paralytic form. Limbic signs are predominant in furious rabies while paralysis of lower motor neuron is hallmark for paralytic rabies[10,12]. Even after recovery, most rabies survivors suffer from neurological impairment[6,13]. As a consequence, an “ideal” effective immunological defense against rabies would be the interception of virus before productive neuronal infection, considering Copyright @ 2020 by Ananda RA and HH Publisher. This work under licensed under the Creative Commons Attribution- NonCommercial 4.0 International Lisence (CC-BY-NC4.0) *Correspondence: Vengadesh Letchumanan, Novel Bacteria and Drug Discovery (NBDD) Research Group, Microbiome and Bioresource Research Strength (MBRS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia. vengadesh.letchumanan1@monash.edu. 2 there is still established, effective therapy for those who developed rabies encephalomyelitis[14]. Canine rabies remains endemic in most developing countries, it is a huge global burden with estimated 3.7 million disability-adjusted life years and 8.6 billion USD economic losses every year[15]. The World Health Organization (WHO) has issued a notice in the past to discontinue the usage of nerve tissue vaccine and replace the vaccination program with newer vaccine produced from cell-culture or embryonated eggs[1,16]. These newer vaccines typically consist of purified inactivated virus that can be used as prevention (i.e. pre-exposure prophylaxis, PrEP) and treatment (i.e. post exposure prophylaxis, PEP). Thus, the current review aims to provide an overview on the characteristics of RABV before exploring available vaccines and those which are in development. Indeed, rabies may not seem like a disease that can be eradicated completely worldwide, thus it is imperative to continuously seek for safer vaccines or drugs with higher efficacy to curb the spread of such harmful pathogens. Discovery and characteristics of RABV As one of the oldest communicable disease known to man, rabies was documented several times in historical records, as early as 4,000 years ago in the pre-Mosaic Eshnunna Code[17–19]. In the code, it was stated that the owner of a rabid dog that bit a person who later died due to rabies must pay a fine. Rabies is an acute, lethal disease marked by encephalomyelitis in which the causative agents are identified to be viruses belong to the genus Lyssavirus. RABV or taxonomically known as Rabies Lyssavirus (under family: Rhabdoviridae, genus: Lyssavirus) is a negative-strand RNA virus. In general, those within the genus Lyssavirus are enveloped RNA virus that are viewed as bullet-shaped when cut tangen- tially or “bulls-eye” in cross sectional view under trans- mission electron microscope[20,21]. The genome of Lyssaviruses is approximately 11–12kb in size, encoding five proteins including glycoprotein (G), phosphoprotein (P), nucleoprotein (N), matrix protein (M), RNA-dependent RNA polymerase (L) (Figure 1) [22,23]. Belonging to phylogroup I, RABV seems to be far more “adaptable” compared to other strain in the same phylogroup — circulates in both Chiroptera (i.e. bats) and Carnivora (i.e carnivores) including wolves, foxes, shunks and dogs[24]. Several strains of RABV have been previously described and it has been discussed that certain polymorphisms within the genome can alter virulence and transmission[25]. For RABV, its genome encodes viral proteins in the sequence of 3’-N-P-M-G-L-5’[26,27]. The viral structure consists of M protein encoded by gene M and transmembrane G protein encoded by gene G. G protein plays critical roles in the pathogenesis of rabies by binding to neural receptors and cellular entry via fusion with the cellular membrane[28–30]. As the only surface proteins, G protein is the only protein that is capable of inducing production of virus neutralizing antibodies (VNAs) by the host, therefore essential in determining the evasiveness of RABV against the host immune system[30,31]. A study in 2019 compared laboratory-adapted RABV strain (B2c) and a wild type (wt) RABV isolated from rabid dog in Mexico in 1990s (DRV); the team discovered that lesser G molecules were incorporated into mature virions by wt RABVs when compared to laboratory-adapted RABVs[30]. While recombinant virus with additional G protein (i.e. triple G expression) showed higher expression and incorporation of G protein, the virus activated more dendritic cells (DC) compared to its corresponding wild type form. Conversely, wild type RABVs that were treated with subtilisin or Dithiothreitol (DTT)/Nonidet P-40 (NP40) to remove G protein failed to activate any DC and/or VNAs expression. Without G protein, these G protein-depleted virus evaded the host immune response and caused lethal infection in mice. Furthermore, another study showed that single amino acid change(s) at position of 255 or 349 in G protein decreased the viral pathogenicity of RABV[31,32]. For instance, after introducing the amino acid change at position 349 nucleotide substituting glycine with glutamine (Gly349→Glu349), the mutant strain (known as rGDSH-G349) exhibited decreased RABV pathogenicity without affecting its propagation rate[32]. On top of that, the same strain was able to induce higher immunogenicity in mice with higher level of VNA observed compared to its parent strain. Altogether, these important findings greatly benefited the scientific community by providing crucial insights into “behaviour changes” of the virus while at the same time enabling researchers to exploit these mutation points for development of therapeutic drugs and vaccines against rabies. Rabies vaccine development... Figure 1. Illustration of rabies virus genome and its common animal reservoir. 3 Ananda RA et al. tissue-based vaccines were developed and used as rabies vaccine but they are being phased out in most countries in the 21st century since the introduction of non-neural tissue- based vaccines. In addition, the crude neural vaccines made from sheep or mouse brains caused severe adverse effects and neurological sequalae including acute demyelinating encephalitis[46,47]. Even so, a few countries including Ethiopia are still using neural vaccines due to their affordability and high cost of newer vaccine[46,48]. As for preventive measures, WHO recommends rabies PrEP for individuals who are at high risk of exposure to rabies including veterinarians, laboratory workers, travellers or residents of rabies- endemic nations[1,49]. PrEP obviates rabies immunoglobulins administration and reduces the number of vaccine doses required when an individual is exposed to rabies[1,49-51]. According to WHO guidelines, a complete PrEP consists of single-dose intramuscular (IM) or two-site intradermal (ID) vaccination on both day 0 and day 7. At the same time, WHO has also published a detailed guidelines and recommendation on PEP to assist physicians in making decision on treatment: (i) Category I involves touching of animals or licks on intact skin; (ii) Category II involves nibbling of uncovered skin or non-bleeding minor abrasions; and (iii) Category III involves transdermal bites, direct contact with bats, licks on broken skins or mucous membranes[1,51]. No PEP is indicated for category I exposure, but only active immunization (i.e. vaccine) will be given for those with category II exposure. For category III exposed individuals, they will be given both active and passive immunization (i.e. vaccine and monoclonal antibodies administration). The recommended dose of passive immunization is given at 20 IU/kg body weight for HRIG and 40 IU/kg body weight for ERIG and F(ab’)2 products. Full dose of rabies immunoglobulins (RIG) can be given into or around wound site, but it can be diluted with physiological buffered saline to ensure better wound coverage in severe cases. Instead, purified cell-culture- or embryonated-egg- based rabies vaccines can be administered intramuscularly or intradermally[1,36]. PEP regimens recommended by WHO include two-sites ID rabies immunization (2-2-2-0-0) on day 0, 3 and 7; two-weeks IM rabies immunization (1-1-1-1-0) on day 0, 3, 7 and 14; three-weeks IM rabies immunization (2-0-1-0-1) on day 0, 7 and 21–28[1,50,51]. IM and ID immunization were commonly recommended because subcutaneous injections of rabies vaccines failed to induce sufficient antibody response after 1 month completing immunization protocol[52]. Receiving rabies vaccination and RIG within first 7 days and 48 hours respectively is considered as timely PEP response[53]. Though, people who received at least two doses of rabies pre-exposure vaccines do not require RIG infusion [1,51]. In events of re-exposure to animal bites, a previously immunised patient only require booster injections on day 0 and 3[49-51]. So the next important question would be — What are these vaccines make of? As discussed earlier, the host immune system must first recognize the pathogens before initiating “attacks” on the intruders. Having that said, it may seem to be unwise to inject someone with live virus to activate someone’s immune system; nevertheless, looking at the history, one of the earlier version of “vaccination program” was done in small pox known as variolation, whereby they On the other hand, the N protein is thought to be a preferred target for phylogenetic studies given that it’s highly conserved and expressed while accountable for activating immunogenic response from the host[33–35]. As a matter of fact, N protein which forms the major component of helicoidal nucleocapsid that encapsidates the genomic RNA plays a determining role in viral replication; it facilitates the temporal transition between transcription and replication of the viral genome during the replicative cycle[35]. In contrast, the phosphoprotein encoded by gene P serves as a cofactor for L protein, connecting it to N protein and finally leading to the formation of ribonucleoprotein complex in viral RNA synthesis[36,37]. Besides polymorphism, the rearrangement of viral genes such as P and N has been shown to affect its pathogenicity and immunogenicity. A team led by Mei et al. in 2019 found that the rearrangement of gene P in RABV led to its low gene expression which then suppressed N gene and attenuated the pathogenicity of the virus [32,33]. Similar results were reported by Morimoto and team whereby the P-gene deficient (def-P) virus was apathogenic in adult and suckling mice. It was also described that even though the def-P virus can perform the primary RNA transcription, no further progeny virus was produced by the infected host (with def-P virus)[37]. Located on the third position in RABV genome, the M protein encoded by gene M is an important component during viral assembly and budding, covering the RNP coil and maintaining the viral bullet-shaped form [38,39]. On top of that, some studies have highlighted the role of M protein in viral transcription, whereby genetic manipulation on gene M via codon deoptimization led to inhibition of RABV replication at the initial stage of infection but increased viral titre at later stages[40,41]. Likewise, the codon deoptimization strain caused higher level of apoptosis in neuronal cell compared to its parental strain[42]. Besides shedding light on the transmission and replication mechanisms of RABV, the understanding on its genomic content allows researchers to identify and exploit these “weak points” in designing treatments or vaccines against this deadly virus, while monitoring RABV outbreaks and evolution. Treatment and vaccines development against Rabies lyssavirus for human use In order to fend off infections, the infected host needs to have sufficient and/or adequate immune response to first recognize the infectious agent(s) before eliminating it from the body. Before discussing in-depth about each vaccines that are in-use or in development (i.e. novel), it is important to note that currently in-use vaccines for rabies can be used as prevention (i.e. pre-exposure prophylaxis, PrEP) and treatment (i.e. post exposure prophylaxis, PEP); however, the only difference between these two lies in immunization schedule[43,44]. Moreover, there are two forms of immunizations: (a) passive immunization — by administration of monoclonal antibodies (e.g. human rabies immunoglobulins (HRIG), equine rabies immunoglobulin (ERIG)) and (b) active immunization which involves the use of cell culture- or embryonated egg-based inactivated virus[44,45]. In 1888, crude nerve 4 inoculate a boy with materials from cowpox pustule and observed protective effect against matter from smallpox lesion[54]. For RABV, there have been many studies looking into potentially more effective vaccines over the years, apart from the attenuated RABV vaccines that are currently in use. Nucleic acid-based vaccines are getting more popular these days, as researchers are working around the clock to develop them given that this approach combines the positive attributes of both live-attenuated and subunit vaccines[55]. A research team in Germany successfully developed a synthetic messenger RNA (mRNA) based vaccine which consists of an optimized non-replicating rabies virus glycoprotein (RABV-G) mRNA sequence in 2016. When compared with licensed rabies vaccines, this mRNA vaccine managed to induce comparable CD4+ T cells and CD8+ T cells responses upon two injections[56]. Subsequently in 2017, Stitz and team described another attractive feature for their mRNA vaccine — thermostability; they showed that the mRNA vaccine that retained its immunogenicity and protective effects against RABV even after exposure to temperatures as high as 70°C[57]. The development of thermostable vaccines provides extended shelf life in challenging conditions especially in tropical countries and economical vaccine stockpiling in preparation for epidemic threats. In fact, a Phase I clinical trial carried out in 2016 using the same mRNA vaccine technology (RNActive®), studying the safety of and immunogenicity of this vaccine in healthy volunteers (NCT02241135)[58]. A total of 101 participants were enrolled and vaccinated with 306 doses of mRNA (80–640 μg) by needle-syringe or needle-free devices (via intradermal or intramuscular route). As the first drug substance of mRNA vaccine against RABV, CV7201 or nadorameran (as named by WHO) was described as generally safe with a reasonable tolerability profile. The same study reported the observation on VNA titres of 0·5 IU/mL or more across dose levels and schedules in 71% of participants given 80 μg or 160 μg CV7201 doses intradermally and 46% of participants given 200 μg or 400 μg CV7201 doses intramuscularly. Nonetheless, 57% of them (i.e. 8 out of 14 participants) achieved titres of 0·5 IU/mL or more after receiving needle-free booster shot of CV7201 at 80 μg intradermally, while those underwent intradermal or intramuscular needle- syringe injection failed to respond (i.e. no immune response) except one participant who received 320 μg of CV7201 intradermally. Additionally, another recent study highlighted that the co-administration of RNA- based adjuvant CV8102 with licensed vaccine for rabies, Rabipur® in Phase I clinical trial (EudraCT No. 2013-004514-18, NCT02238756) indicated that CV8102 was safe up to 50 μg and enhanced immunogenicity of the licensed rabies vaccine significantly[59]. Even so, there is still much to do to determine the appropriate vaccination dose and schedule of mRNA vaccine alone or as adjuvant for PrEP and/or PEP regime. Besides that, there are several groups discussing the use of viral vector-based vaccines against RABV, such as via the incorporation of RABV glycoprotein genes into West Nile virus backbone to induce protective effect [7,60–62]. In the study by Giel-Moloney and team, the RABV G protein expression remained stable after multiple in vitro passages and the vaccine exhibited durable protective immunity with high titres of complementing T helper cells[60]. The vaccine which uses RepliVax® technology is a highly promising vector delivery system, given that immunized dogs displayed durable protective immunity when tested at one- and two-year post immunization. In addition to that, there are other recombinant rabies vaccines generated using different viral vector systems, such as poxvirus[7,63,64], Newcastle disease virus[65], parainfluenza virus[66], adenovirus[67,68], or baculovirus[69,70]. Despite of that, these vaccines may not be available for clinical use at the moment, particularly regarding efficacy restricted to certain species but not human, safety considerations, and similar to the concern with mRNA vaccines—usage as PEP and/or PrEP vaccination. Looking on the bright side, there are two ongoing Phase I clinical trial studying the safety and immunogenicity of novel recombinant rabies vaccines, ChAd155-RG (NCT04019444) and ChAdOx2 RabG (NCT04162600)[71,72]. In reality, another critical point to consider in designing recombinant vaccine is that the viral vector used must not be pathogenic while being able to trigger protection against certain pathogens (including RABV)[73,74]. Decades have passed since the first vaccine for smallpox and an increasing number of researchers are considering the possibility of immunization against multiple pathogens with the use of single viral vector carrying fragments of another virus (e.g. multivalent vaccine)[74,75]. For instance, a novel vaccine consisting of inactivated RABV that expressed protein fragments of Middle East respiratory syndrome coronavirus (MERS-CoV) was proven to be effective in producing antibodies against rabies and MERS-CoV infection[74]. Developed by Wirblich and team, BNSP333-S1 is an inactivated RABV-MERS S-based vaccine and the team observed increased antigen-specific IgG responses over time after each immunization. Besides that, there is another genetically modified RABV vector- based Rift Valley fever virus (RVFV) vaccine which induced significant rabies VNA level but it is still unsure whether it can protect against RVFV as it failed to induce RVFV VNA (despite high titres of anti-RVFV IgG antibodies)[75]. Therefore, multivalent vaccines against rabies and other infectious diseases can be developed, but further validation tests should be conducted thoroughly in clinical studies to confirm its efficacy and safety. Current measures in place to control the spread of RABV from animals to humans Animal mass vaccination While the development of RABV vaccine for human use is essential to combat against RABV, the preventive measures and management of wild life including carrier of RABV are equally important. WHO recommended that mass vaccination of at least 70% rabies-susceptible dog population is essential to achieve herd immunity and contain the virus as 95% of human rabies cases were caused by dog bites[1]. Although mass vaccination of dogs is the most cost-effective method for significant decrease Rabies vaccine development... 5 neutralization tests when other samples collected are of low quality[96]. Therefore, bi-annual and annual bait distribution schedules are sufficient for rabies control in wildlife reservoirs[92]. Outbreak prevention Appropriate health promotion measures, coordinated rabies surveillance and mass vaccination program can prevent rabies outbreaks[97]. Introduction of rabies-infected subject to a community could be an imminent threat and trigger an outbreak, especially for a previously rabies-free region[98]. In developing countries, significant stray dog population and inevitable dog movement are recognized as public health risk and could result in rabies outbreak with subsequent bites to other animals by an infected animal[99,100]. While stray dog population in rural regions is correlated with carcass availability, economic implications of dog bites and rabies infections are significant following decline in vultures population. Local government should implement strategies for carcass disposal including incinerations. As significant stray dog population and rabies infection are major concerns, Bhutan had implemented catch-neuter-vaccinate- release (CNVR) program[99]. Moreover, rabies outbreak in wildlife is of huge concern as animals like fox and wild dogs are highly mobile and travel over a long distance between habitats in different countries, further enhancing the spread of rabies infection[101]. Health promotion measures including domestic dog control regulation and mass vaccina- tion program had been implemented in the early 19th century during the Japanese colonial period[102]. However, the Japanese colonial government was widely criticized in Korea for brutality and poor understanding of traditional dog-human relationship. In the 21st century, cultural obligations to dog population remains significant in the rural communities, especially Indigenous community, as harming dogs will result in sickness[98]. During an outbreak in India, most people only received rabies preventive measures from friends and consumed traditional herbal medicines[100]. Poor knowledge and practices of preventive measures reflected on the health-seeking behaviour of rural communities following an outbreak. As a previously rabies-free region, rabies remains endemic in Bali since the introduction of the virus by a sub-clinically infected dog in 2008[103,104]. Poor surveillances, diagnostic facilities and treatment policy in 2008 had resulted in circulation of rabies virus across the island following the outbreak[104]. However, local authority in Bali has implemented Program Dharma to improve dog care practices and facilitate mass vaccination program, in addition to reducing roaming dog density. Hence, public health officials should organise education awareness campaign to emphasize the significance of dog ownerships and public cooperation as preventive strategies of outbreak[103]. Poor handling of outbreak in wildlife or local community could facilitate transmission of zoonotic diseases to human. Despite its rabies-free status, Australia has identified potential areas of rabies incursion and implemented community-based health promotion approach to increase preparedness of the local community[98]. Rabies surveillance including strict monitoring programs is important for prompt control measures as potential cases are identified to halt spreading[97]. in human rabies cases and mortality, local government particularly in endemic countries often neglect these preventive efforts [76,77]. According to World Organization for Animal Health (OIE), animals are considered to have protective immunity against rabies infection if they have minimum post-vaccination rabies VNA of 0.5 IU/ mL[78]. Several canine rabies control strategies includ- ing immunization, movement restriction and culling of stray dogs were carried out in several Asian and African countries over many decades but were not effective in eliminating rabies from the population[79,80]. Introduction of a simple centralised canine rabies vaccination campaign to a rural area in Africa increased vaccination coverage from initial estimated 9.5% to be- tween 60 and 70%[79]. There was a significant decline in incidence of dog rabies by 97% after the second vacci- nation programme with more than 60% coverage of the dog population. However, in Korea, canine rabies was successfully controlled with low vaccination coverage, which ranged between 30% and 50%[81]. Genetic, temporal and spatial heterogeneities that influence contact and transmission rate can have significant impact on the design of immunization program[82]. Besides vaccination coverage, relative success of large-scale vaccination program is also determined by frequency of vaccination campaign and dog density in the area[83]. Satisfactory rabies knowledge and awareness in the population will increase rabies immunization coverage[84]. In countries with high birth and death rate of dogs, there is substantial risk of outbreaks occurrence between vaccination campaigns due to rapid decline in overall population coverage following a campaign[79]. Oral rabies vaccination (ORV) is a cost-effective and socially acceptable technique that can be incorporated into large scale rabies control programmes for canine or wildlife reservoirs[85]. International researchers have generated several effective vaccines over the years. In the late 20th century, a mass vaccination programme using live attenuated RABV vaccine (ERA-BHK21) successfully eliminated Arctic rabies virus variant from red fox population in eastern Ontario[86]. Similar result was observed in Europe where the spread of rabies infection was prevented by vaccinating approximately 60% of fox population with a different live vaccine (SAD)[2]. Despite the successful results and cost-effectiveness, the use of live-attenuated vaccines in ORV programmes remains controversial due to residual pathogenicity, vaccine-induced rabies infection, thermal instability and ineffectiveness of oral immunization in rabies reservoirs including skunks and raccoons[2,85–91]. Alternatively, recombinant vaccines were constructed from heterologous virus vectors expressing RABV glycoprotein and were proven to have improved safety profile and thermal stability[92,93]. ONRAB® is a recombinant oral RABV vaccine generated using human adenovirus vector that expresses RABV glycoprotein and often distributed as bait to animals[92]. ONRAB® induced sufficient immune response in wildlife reservoirs including red foxes, raccoons and skunks with high survival rate after rabies challenge test 1 year post-vaccination[92,94,95]. During oral vaccination campaign, muscle extracts and thoracic liquid are considered potential samples for virus Ananda RA et al. 6 Conclusion and future recommendation Since the description of rabies by the historical records, humans have made a long way in the discovery and development of vaccines for RABV. In actual, thorough research into molecular virology, immunology and epidemiology have provided remarkable understanding of the circulation of rabies virus. Even though the current inactivated vaccine may seem to be working well, it is still far from “perfect” with some studies found inadequate antibodies titre among veterinary students at 2 years after pre-exposure rabies vaccination; the levels of antibodies was independently influenced by several variables including gender, vaccine type or manufacturer, BMI and interval between first and third vaccine doses[105,106]. Furthermore, the currently approved vaccine for rabies needs to be refrigerated, complicating the logistics problem which can lead to delay in treatment time[107]. Global burden of rabies infection is notable, but the zoonotic diseases as such is preventable. Collaborative efforts from several countries have played an important role in improving public health and relieving the economic burden. As part of the drug discovery process, researchers have been studying the potential of small molecules or even peptides expressed by microorganisms and plants to be used to prevent and/or treat infectious diseases including RABV[108–117]. Among these studies, tobacco mosaic virus (TMV) isolated from chimeric plants expressed spherical particles (i.e. coat protein of alfalfa mosaic virus fused with antigenic peptides of RABV) that can improve rabies vaccine protective properties due to the presence of RABV antigenic peptides[108,109]. Yusibov and team showed that using plants as tool to produce antigens to be used in vaccines provide several advantages including lack of contamination of other human pathogens, reasonable ease of genetic manipulation and economical production[108]. After purification steps, spherical particles formed from the recombinant AIMV CP was used to immunize mice and subsequently resulted in an antigen- specific humoral immune response, accompanied with VNA. Apart from that, nucleoside analogs are potential antiviral compounds because they can act as competitive inhibitors to interfere nucleic acid biosynthesis during replication of viral genome. For example, small molecule drugs such as ribavirin (which is an antiviral drug against respiratory syncytial virus) and favipiravir (i.e. antiviral drug against influenza) have been shown to be effective against RABV as well by acting as competitive inhibitors that interfere with nucleic acid biosynthesis during replication of viral genome[110–113]. Along with these, there is also potential use of these molecules in combination and/or as adjuvant (booster) to increase the efficacy or performance of the vaccine. However, further studies on the pathogenic mechanism of rabies virus and therapeutic approaches are still required to prevent the deathly infection following clinical manifestation. Having that said, integrated interventional strategy emphasizing human health and animal health is essential and via the collaboration between health authorities and the public, it is highly possible to control and prevent further spread of zoonotic disease like rabies. Author Contribution The literature review and manuscript writing were performed by R-AA and H-LS. H-LS and VL provided vital guidance and support as content expert and proofread of the writing. Conflict of Interest All the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Acknowledgements Authors would like to acknowledge the support by Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia. Reference 1. World Health Organization. WHO expert consultation on rabies: third report. World Health Organization; 2018. 2. Wandeler AI, Capt S, Kappeler A, et al. Oral immunization of wildlife against rabies: concept and first field experiments. Rev Infect Dis 1988; 10 (Supplement 4): S649–S653. 3. Roy A, Phares TW, Koprowski H, et al. Failure to open the blood-brain barrier and deliver immune effectors to central nervous system tissues leads to the lethal outcome of silver-haired bat rabies virus infection. J Virol 2007; 81(3): 1110–1118. 4. Singh R, Singh KP, Cherian S, et al. Rabies—epidemiology, pathogenesis, public health concerns and advances in diagnosis and control: a comprehensive review. Vet Quart 2017; 37(1): 212–251. 5. Klingen Y, Conzelmann KK and Finke S. Double-labeled rabies virus: live tracking of enveloped virus transport. J Virol 2008; 82(1): 237–245. 6. Willoughby Jr RE, Tieves KS, Hoffman GM, et al. Survival after treatment of rabies with induction of coma. N Engl J Med 2005; 352(24): 2508–2514. 7. Gholami A, Shirzadi MR, Asouri M, et al. Seroconversion after three doses of intramuscular rabies vaccine as a post-exposure treatment. Virus Res 2020; 278:197883. 8. Qi L, Su K, Shen T, et al. Epidemiological characteristics and post- exposure prophylaxis of human rabies in Chongqing, China, 2007–2016. BMC Infect Dis 2018; 18(1): 1–7. 9. Mitrabhakdi E, Shuangshoti S, Wannakrairot P, et al. Difference in neuropathogenetic mechanisms in human furious and paralytic rabies. J Neurol Sci 2005; 238(1–2) :3–10. 10. Ayatollahi J, Sharifi MR and Shahcheraghi SH. Severe abdominal pain as the first manifestation of rabies. Jundishapur J Microbiol 2014; 7(8). 11. Tian Z, Chen Y and Yan W. Clinical features of rabies patients with abnormal sexual behaviors as the presenting manifestations: a case report and literature review. BMC Infect Dis 2019; 19(1): 679. 12. Hemachudha T, Wacharapluesadee S, Mitrabhakdi E, et al. Pathophysiology of human paralytic rabies. J Neurovirology 2005; 11(1): 93–100. 13. Karande S, Muranjan M, Mani RS, et al. Atypical rabies encephalitis in a six-year-old boy: clinical, radiological, and laboratory findings. Int J Infect Dis 2015; 36:1–3. 14. Jackson AC. Therapy of human rabies. In: Rabies. Academic Press; 2013. p. 575–589. 15. Hampson K, Coudeville L, Lembo T, et al. Estimating the global burden of endemic canine rabies. PLoS Negl .Trop. Dis. 2015; 9(4): e0003709. 16. World Health Organization. WHO guide for rabies pre and post-exposure prophylaxis in humans. Department of Neglected Tropical Diseases– Neglected Zoonotic Diseases Team; 2010. 17. Tarantola A. Four thousand years of concepts relating to rabies in animals and humans, its prevention and its cure. Trop Med Infect Dis 2017; 2(2): 5. doi: 10.3390/tropicalmed2020005. 18. Baer GM. The natural history of rabies. CRC press; 1991. 19. Yuhong W. Rabies and rabid dogs in Sumerian and Akkadian literature. J Amer Orient Soc 2001; 32–43. doi: 10.2307/606727. 20. Goldsmith CS and Zaki SR. Demonstration of Lyssaviruses by Electron Microscopy. In: Current Laboratory Techniques in Rabies Diagnosis, Research and Prevention. Volume 2. Academic Press; 2015. p. 5 –11 21. Fekadu M. Pathogenesis of rabies virus infection in dogs. Rev Infect Dis Rabies vaccine development... 7 1988; 10 (Supp 4): S678–S683. 22. Rupprecht C, Kuzmin I and Meslin F. Lyssaviruses and rabies: current conundrums, concerns, contradictions and controversies. F1000Research 2017; 6. 23. Marston DA, Ellis RJ, Wise EL, et al. Complete genome sequence of Lleida bat lyssavirus. Genome Announ 2017; 5(2). 24. Ding NZ, Xu DS, Sun YY, et al. A permanent host shift of rabies virus from Chiroptera to Carnivora associated with recombination. Sci Rep 2017; 7(1): 1–9. 25. Archer E, Houldcroft CJ. Rabid about whole lyssa genomes. Nat Rev Microbiol 2014; 12(5): 316. doi: 10.1038/nrmicro3263. 26. Albertini AA, Ruigrok RW and Blondel D. Rabies virus transcription and replication. In: Advances in virus research. Vol. 79. Academic Press; 2011. p. 1–22. 27. Davis BM, Rall GF and Schnell MJ. Everything you always wanted to know about rabies virus (but were afraid to ask). Annu Rev Virol 2015; 2: 451–471. 28. Zhang G, Wang H, Mahmood F, et al. Rabies virus glycoprotein is an important determinant for the induction of innate immune responses and the pathogenic mechanisms. Vet Microbiol 2013; 162(2–4): 601–13. 29. Faber M, Pulmanausahakul R, Nagao K, et al. Identification of viral genomic elements responsible for rabies virus neuroinvasiveness. Proc Nat Acad Sci 2004; 101(46): 16328–32. 30. Li C, Zhang H, Ji L, et al. Deficient incorporation of rabies virus glycoprotein into virions enhances virus-induced immune evasion and viral pathogenicity. Viruses 2019; 11(3): 218. 31. Luo J, Zhang B, Lyu Z, et al. Single amino acid change at position 255 in rabies virus glycoprotein decreases viral pathogenicity. FASEB J 2020. 32. Luo J, Zhang B, Wu Y, et al. Amino Acid Mutation in Position 349 of Glycoprotein Affect the Pathogenicity of Rabies Virus. Front Microbiol 2020; 11. 33. Mei M, Long T, Zhang Q, et al. Phenotypic consequence of rearranging the N gene of RABV HEP-Flury. Viruses. 2019; 11(5): 402. 34. Mehta S, Charan P, Dahake R, et al. Molecular characterization of nucleoprotein gene of rabies virus from Maharashtra, India. J Postgrad Med 2016; 62(2): 105. 35. de Almeida GL, Cargnelutti JF, Ries AS, et al. Sequence analysis of nucleoprotein gene reveals the co-circulation of lineages and sublineages of rabies virus in herbivorous in Rio Grande do Sul state, Brazil. Braz J Microbiol 2020; 1–10. 36. Wunner WH and Conzelmann KK. Rabies virus. In: Jackson AC, editor. Rabies, 3rd ed. London, United Kingdom: Academic Press; 2013. p. 17–60. 37. Okada K, Ito N, Yamaoka S, et al. Roles of the rabies virus phosphoprotein isoforms in pathogenesis. J Virol 2016; 90(18): 8226–8237. 38. Morimoto K, Shoji Y and Inoue S. Characterization of P gene- deficient rabies virus: propagation, pathogenicity and antigenicity. Virus Res 2005; 111(1): 61–67. 39. Tordo N and Kouknetzoff A. The rabies virus genome: an overview. Onderstepoort J Vet Res 1993; 60: 263–269. 40. Wunner WH. Rabies virus. In: Rabies. Academic Press; 2007. p. 23–68. 41. Finke S, Mueller-Waldeck R and Conzelmann KK. Rabies virus matrix protein regulates the balance of virus transcription and replication. J Gen Virol 2003; 84(6): 1613–21. 42. Luo J, Zhang Y, Zhang Q, et al. The deoptimization of rabies virus matrix protein impacts viral transcription and replication. Viruses 2020; 12(1): 4. 43. Ertl HC. New rabies vaccines for use in humans. Vaccines 2019; 7(2): 54. 44. World Health Organization. WHO vaccine reaction rates information sheets. Available from: https://www.who.int/vaccine_ safety/initiative/tools/vaccinfosheets/en/ 45. World Health Organization. Information sheet, observed rate of vaccine reactions, rabies vaccine. Available from: https://www. who.int/vaccine_safety/initiative/tools/Rabies_Vaccine_rates_ information_sheet.pdf?ua=1 46. Nandi S and Kumar M. Development in immunoprophylaxis against rabies for animals and humans. Avicenna J Med. Biotechnol 2010; 2(1): 3. 47. Shah I. Acute demyelinating encephalomyelitis due to neural antirabies vaccine. J Travel Med 2008; 15(1): 58–9. 48. Hampson K, Ventura F, Steenson R, et al. The potential effect of improved provision of rabies post-exposure prophylaxis in Gavi- eligible countries: A modelling study. Lancet Infect Dis 2019; 19(1): 102–111. 49. Manning SE, Rupprecht CE, Fishbein D, et al. Human rabies prevention—United States, 2008: recommendations of the advisory committee on immunization practices. MMWR Recomm Rep 2008; 57(RR-3):1–28. 50. World Health Organization. International travel and health: Rabies. Available from: https://www.who.int/ith/vaccines/rabies/ en/ 51. World Health Organization. Rabies vaccines and immunoglobulins: WHO position April 2018. Available from: https://www.who.int/ immunization/policy/position_papers/pp_rabies_summary_2018. pdf 52. Yamamoto K, Ujiie M, Noguchi A, et al. Rabies post-exposure prophylactic vaccination for returning travelers to Japan. J Infect Chemo 2019; 25(12): 931–935. 53. Soentjens P, Croughs M, Burm C, et al. Time of administration of rabies immunoglobulins and adequacy of antibody response upon post-exposure prophylaxis: a descriptive retrospective study in Belgium. Acta Clinica Belgica 2019: 1–7. 54. Riedel S. Edward Jenner and the history of smallpox and vaccination. In: Baylor University Medical Center Proceedings. Taylor & Francis 2005; 18(1): 21–25. 55. Deering RP, Kommareddy S, Ulmer JB, et al. Nucleic acid vaccines: prospects for non-viral delivery of mRNA vaccines. Expert Opin Drug Del 2014; 11(6): 885–899. 56. Schnee M, Vogel AB, Voss D, et al. An mRNA vaccine encoding rabies virus glycoprotein induces protection against lethal infection in mice and correlates of protection in adult and newborn pigs. PLoS Negl Trop Dis 2016; 10(6): e0004746. 57. Stitz L, Vogel A, Schnee M, et al. A thermostable messenger RNA based vaccine against rabies. PLoS Negl Trop Dis 2017; 11(12): e0006108. 58. Alberer M, Gnad-Vogt U, Hong HS, et al. Safety and immunogenicity of a mRNA rabies vaccine in healthy adults: an open-label, non-randomised, prospective, first-in-human phase 1 clinical trial. Lancet. 2017; 390(10101): 1511-1520. 59. Doener F, Hong HS, Meyer I, et al. RNA-based adjuvant CV8102 enhances the immunogenicity of a licensed rabies vaccine in a first- in-human trial. Vaccine 2019; 37(13): 1819–1826. 60. Giel-Moloney M, Rumyantsev AA, David F, et al. A novel approach to a rabies vaccine based on a recombinant single-cycle flavivirus vector. Vaccine 2017; 35(49): 6898–6904. 61. Yang DK, Kim HH, Lee KW, et al. The present and future of rabies vaccine in animals. Clin Exp Vaccine Res 2013; 2(1): 19–25. 62. Astray RM, Jorge SA and Pereira CA. Rabies vaccine development by expression of recombinant viral glycoprotein. Arch Virol 2017; 162(2): 323–332. 63. Amann R, Rohde J, Wulle U, et al. A new rabies vaccine based on a recombinant ORF virus (parapoxvirus) expressing the rabies virus glycoprotein. J Virol 2013; 87(3): 1618–1630. 64. Weyer J, Rupprecht CE and Nel LH. Poxvirus-vectored vaccines for rabies—A review. Vaccine 2009; 27(51): 7198–7201. 65. Ge J, Wang X, Tao L, et al. Newcastle disease virus-vectored rabies vaccine is safe, highly immunogenic, and provides long-lasting protection in dogs and cats. J Virol 2011; 85(16): 8241–8252. 66. Chen Z, Zhou M, Gao X, et al. A novel rabies vaccine based on a recombinant parainfluenza virus 5 expressing rabies virus glycoprotein. J Virol 2013; 87(6): 2986–2993. 67. Shen CF, Lanthier S, Jacob D, et al. Process optimization and scale- up for production of rabies vaccine live adenovirus vector (AdRG1. 3). Vaccine 2012; 30(2): 300–306. 68. Ertl HC and Wilson JM, inventors. University of Pennsylvania, Wistar Institute, assignee. Replication-defective adenovirus human type 5 recombinant as a rabies vaccine carrier. United States patent US 5,698,202. 1997. 69. Prehaud C, Takehara K, Flamand A, et al. Immunogenic and protective properties of rabies virus glycoprotein expressed by baculovirus vectors. Virol 1989; 173(2): 390–399. 70. Fu ZF, Rupprecht CE, Dietzschold B, et al. Oral vaccination of racoons (Procyon lotor) with baculovirus-expressed rabies virus glycoprotein. Vaccine 1993; 11(9): 925–928. 71. Wang C, Dulal P, Zhou X, et al. A simian-adenovirus-vectored rabies vaccine suitable for thermostabilisation and clinical development for low-cost single-dose pre-exposure prophylaxis. PLoS Negl Trop Dis 2018; 12(10): e0006870. 72. Cicconi P, Jones C, Sarkar E, et al. First-in-human randomized study to assess the safety and immunogenicity of an investigational Respiratory Syncytial Virus (RSV) vaccine based on Chimpanzee- Adenovirus-155 viral vector–Expressing RSV fusion, nucleocapsid, and antitermination viral proteins in healthy adults. Clin Infect Dis 2020; 70(10): 2073–81. 73. Bessis N, GarciaCozar FJ and Boissier MC. Immune responses to gene therapy vectors: influence on vector function and effector mechanisms. Gene therapy. 2004; 11(1): S10–7. 74. Wirblich C, Coleman CM, Kurup D, et al. One-Health: a safe, efficient, dual-use vaccine for humans and animals against middle east respiratory syndrome coronavirus and rabies virus. J. Virol. 2017; 91(2). 75. Zhang S, Hao M, Feng N, et al. Genetically modified rabies virus vector-based rift valley fever virus vaccine is safe and induces efficacious immune responses in mice. Viruses. 2019; 11(10): 919. 76. Nishizono A, Yamada K, Khawplod P, et al. Evaluation of an improved rapid neutralizing antibody detection test (RAPINA) for qualitative and semiquantitative detection of rabies neutralizing antibody in humans and dogs. Vaccine 2012; 30(26): 3891–3896. 77. Bourhy H, Dautry-Varsat A, Hotez PJ, et al. Rabies, still neglected after 125 years of vaccination. PLoS Negl. Trop. Dis. 2010; 4(11): e839. 78. World Organisation For Animal Health (OIE). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. 2018. 79. Cleaveland S, Kaare M, Tiringa P, et al. A dog rabies vaccination campaign in rural Africa: impact on the incidence of dog rabies and human dog-bite injuries. Vaccine 2003; 21(17–18): 1965–1973. 80. Hu RL, Fooks AR, Zhang SF, et al. Inferior rabies vaccine quality and low immunization coverage in dogs (Canis familiaris) in China. Ananda RA et al. 8 Epidemiol Infect 2008; 136(11): 1556–63. 81. Lee JH, Lee JB, Kim JS, et al. Review of canine rabies prevalence under two different vaccination programmes in Korea. Vet Record 2001; 148: 511–512. 82. May RM, Anderson RM. Spatial heterogeneity and the design of immunization programs. Math Biosci 1984; 72(1): 83–111. 83. Woolhouse ME, Haydon DT and Bundy DA. The design of veterinary vaccination programmes. Vet J 1997; 153(1): 41–47. 84. Kazadi EK, Tshilenge GM, Mbao V, et al. Determinants of dog owner- charged rabies vaccination in Kinshasa, Democratic Republic of Congo. PloS One 2017; 12(10): e0186677. 85. Shwiff SA, Nunan CP, Kirkpatrick KN, et al. A retrospective economic analysis of the Ontario red fox oral rabies vaccination programme. Zoonoses Public Health 2011; 58(3): 169–177. 86. Rosatte RC, Power MJ, Donovan D, et al. Elimination of arctic variant rabies in red foxes, metropolitan Toronto. Emerg Infect Dis 2007; 13(1): 25. 87. Artois M, Guittré C, Thomas I, et al. Potential pathogenicity for rodents of vaccines intended for oral vaccination against rabies: a comparison. Vaccine 1992; 10(8): 524–528. 88. Müller T, Bätza HJ, Beckert A, et al. Analysis of vaccine-virus- associated rabies cases in red foxes (Vulpes vulpes) after oral rabies vaccination campaigns in Germany and Austria. Arch Virol 2009; 154(7): 1081–1091. 89. Winkler WG, McLean RG and Cowart JC. Vaccination of foxes against rabies using ingested baits. J Wildlife Dis 1975; 11(3): 382–388. 90. Rupprecht CE, Charlton KM, Artois M, et al. Ineffectiveness and comparative pathogenicity of attenuated rabies virus vaccines for the striped skunk (Mephitis mephitis). J Wildlife Dis 1990; 26(1): 99–102. 91. Rupprecht CE, Dietzschold B, Cox JH, et al. Oral vaccination of raccoons (Procyon lotor) with an attenuated (SAD-B19) rabies virus vaccine. J. Wildlife Dis 1989; 25(4): 548–554. 92. Brown LJ, Rosatte RC, Fehlner-Gardiner C, et al. Oral vaccination and protection of red foxes (Vulpes vulpes) against rabies using ONRAB®, an adenovirus-rabies recombinant vaccine. Vaccine 2014; 32(8): 984–989. 93. Brochier B, Costy F and Pastoret PP. Elimination of fox rabies from Belgium using a recombinant vaccinia-rabies vaccine: an update. Vet Microbiol 1995; 46(1–3): 269–279. 94. Brown LJ, Rosatte RC, Fehlner-Gardiner C, et al. Oral vaccination and protection of striped skunks (Mephitis mephitis) against rabies using ONRAB®. Vaccine 2014; 32(29): 3675–3679. 95. Brown LJ, Rosatte RC, Fehlner-Gardiner C, et al. Immune response and protection in raccoons (Procyon lotor) following consumption of baits containing ONRAB®, a human adenovirus rabies glycoprotein recombinant vaccine. J Wildlife Dis 2012; 48(4): 1010–20. 96. Bedeković T, Lemo N, Lojkić I, et al. Modification of the fluorescent antibody virus neutralisation test-Elimination of the cytotoxic effect for the detection of rabies virus neutralising antibodies. J Virolog Meth 2013; 189(1): 204–208. 97. Tao XY, Li ML, Wang Q, et al. The reemergence of human rabies and emergence of an Indian subcontinent lineage in Tibet, China. PLoS Negl Trop Dis 2019; 13(1): e0007036. 98. Degeling C, Brookes V, Lea T, et al. Rabies response, One Health and more-than-human considerations in Indigenous communities in northern Australia. Soc Sci Med 2018; 212: 60–7. 99. Tenzin T, Namgyal J and Letho S. Community-based survey during rabies outbreaks in Rangjung town, Trashigang, eastern Bhutan, 2016. BMC Infect Dis 2017; 17(1): 281. 100. Brookes VJ, Gill GS, Singh BB, et al. Challenges to human rabies elimination highlighted following a rabies outbreak in bovines and a human in Punjab, India. Zoonoses Public Health 2019; 66(3): 325–336. 101. Canning G, Camphor H and Schroder B. Rabies outbreak in African Wild Dogs (Lycaon pictus) in the Tuli region, Botswana: Interventions and management mitigation recommendations. J Nat Conserv 2019; 48: 71–76. 102. Chun MS. Rabies Outbreaks and Control during the Japanese Colonial Period in Korea. Korean J Med History. 2018; 27(3): 323–356. 103. Utami NW, Agustina KK, Atema KN, et al. Evaluation of community- based dog welfare and rabies project in Sanur, a sub-district of the Indonesian island province of Bali. Front Vet Sci 2019; 6: 193. 104. Putra AA, Hampson K, Girardi J, et al. Response to a rabies epidemic, Bali, Indonesia, 2008–2011. Emerg Infect Dis 2013; 19(4): 648. 105. Banga N, Guss P, Banga A, et al. Incidence and variables associated with inadequate antibody titers after pre-exposure rabies vaccination among veterinary medical students. Vaccine 2014; 32(8): 979–983. 106. Spitzer JA. Gender differences in some host defense mechanisms. Lupus 1999; 8(5): 380–383. 107. Briggs DJ and Hemachudha T. Human rabies vaccines. In: Rabies and Rabies Vaccines. Cham: Springer; 2020. p. 71–82. 108. Funaki M, Tsuchiya F, Maeda K, et al. Virocidin, a new antiviral and antibacterial antibiotic. J Antibiotics: Series A 1958; 11(4): 138–142. 109. Law JW, Letchumanan V, Tan LT, et al. The rising of “Modern Actinobacteria” era. Prog Microbes Mol Biol 2020; 3(1). 110. Law JW, Pusparajah P, Ab Mutalib NS, et al. A review on mangrove actinobacterial diversity: the roles of Streptomyces and novel species discovery. Prog. Microbes Mol Biol 2019; 2(1). 111. Lee LH, Goh BH and Chan KG. Actinobacteria: Prolific Producers of Bioactive Metabolites. Front Microbiol 2020; 11: 1612. 112. Nikitin NA, Matveeva IN, Trifonova EA, et al. Spherical particles derived from TMV virions enhance the protective properties of the rabies vaccine. Data Brief 2018; 21: 742–745. 113. Yusibov V, Modelska A, Steplewski K, et al. Antigens produced in plants by infection with chimeric plant viruses immunize against rabies virus and HIV-1. Proc Nat Acad Sci 1997; 94(11): 5784–5788. 114. Yamada K, Noguchi K, Komeno T, et al. Efficacy of favipiravir (T-705) in rabies postexposure prophylaxis. J Infect Dis 2016; 213(8): 1253–1261. 115. Baranovich T, Wong SS, Armstrong J, et al. EA. T-705 (favipiravir) induces lethal mutagenesis in influenza A H1N1 viruses in vitro. J Virol 2013; 87(7): 3741–3751. 116. Anindita PD, Sasaki M, Okada K, et al. Ribavirin-related compounds exert in vitro inhibitory effects toward rabies virus. Antiviral Res 2018; 154:1–9. 117. Banyard AC, Mansfield KL, Wu G, et al. Re-evaluating the effect of Favipiravir treatment on rabies virus infection. Vaccine 2019; 37(33): 4686–4693. Rabies vaccine development...