Proceeding of Veterinary and Animal Science Days 2016, 8th- 10th June, Milan, Italy 

HAF © 2013 

Vol. III, No. 1s  ISSN: 2283-3927 

   

 

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Keywords 

Edible vaccines, Nicotiana tabacum, 

VTEC strain, Avidity of antibody, 

Streptococcus pneumoniae, 

Monoclonal Antibody 

 

CORRESPONDING AUTHOR 

Angela Lombardi 

angela.lombardi@unimi.it 

 

JOURNAL HOME PAGE 

riviste.unimi.it/index.php/haf 

Avidities of human monoclonal antibodies 

derived from an adult immunized with 

pneumococcal polysaccharide vaccine. 

 

A.Lombardia*, S. Bandib, J. T. Rahkolab, L. Rossia, E. N. Janoffb, 

A.Baldia 

aFaculty of Veterinary Medicine, Department of Health, Animal Science and 
Food Safety Via Celoria 10 20133 Università degli Studi di Milano, Milan. 

 bSchool of Medicine Division of Infectious Disease 12700 East 19th Avenue, 
Box B168 Aurora, CO 80045 University of Colorado Anschutz Medical Campus, 
Aurora Denver, USA. 

 

 
Abstract 
Plant based vaccines provide an instructive opportunity for immunologists. We have developed a plant-

based oral vaccine against verocytotoxin–producing E. coli (VTEC) in piglets (Rossi et. al 2014). We 

engineered two independent lines of Nicotiana tabacum plants for the seed-specific expression of VTEC 

antigens, represented by the major subunit FedA of the F18 adhesive fimbriae and the B-subunit of VT2e 

toxin respectively (Rossi et. al. 2013). Edible vaccines in particular are of interest as they are able to 

stimulate the mucosal immune system to produce secretory IgA (S-IgA) at mucosal surfaces and, 

potentially IgG in the blood. The quality of the antibodies, such as avidity, should be considered in 

evaluating the efficacy of these vaccines. To develop this area, we determined avidity (strength of 

antibody-antigen binding) of IgG to the capsule of another mucosal pathogen, Streptococcus 

pneumoniae. Using pneumococcal capsule-specific IgG human monoclonal antibodies (hMAb) cloned 

from single cells of a subject immunized with pneumococcal vaccine, we defined serotypes specificity 

and the avidity of these antibodies with ammonium thiocyanate (0, 4M, 2M, 1M 0.5M 0.025M) 

dissociation. IgG with lower avidity to the capsule are dissociated at lower NH4SCN levels, whereas IgG 

with higher affinity require higher levels. We identified a range of avidities for 11 hMAB’s (range X-Y 

MNH4SCN).  We will evaluate the avidity of antibodies after immunization with edible vaccines against 

VTEC strain in piglets about which little in known, but as demonstrated in Granoff et al. the high-avidity 

antibodies are required in generating a more effective vaccine. 
 

References 

Baxendale, H. E., Goldblatt, D., 2006. Correlation of Molecular Characteristics, Isotype, and In Vitro Functional Activity of Human Antipneumococcal Monoclonal 

Antibodies. Infect. Immun. 74:1025–1031. 

Rossi, L., Dell’Orto, V., Vagni, S., Sala, V., Reggi, S., Baldi, A., 2014. Protective effect of oral administration of transgenic tobacco seeds against verocytotoxic 

Escherichia coli strain in piglets. Vet Res Comm 38 (1), 39-49. 

 Rossi, L., Di Giancamillo, A., Reggi, S., Domeneghini, C., Baldi, A., Sala, V., Dell’Orto, V., Coddens, A., Cox, E., Fogher, C., 2013. Expression of porcine verocytotoxic 

Escherichia coli antigens in tobacco seeds and evaluation of gut immunity after oral administration in mouse model” JV 14(3), 263-270. 

Schlesinger, Y., Granoff, D.M., 1992. Vaccine Study Group. Avidity and bactericidal activity of antibody elicited by dif ferent Haemophilus influenzae type b 

conjugate vaccines. JAMA 1267, 1489–94. 

Smith, K., Muther, J., Duke, A., McKee, E., Zheng NY., Wilson, PC., James, J.A., 2013. Fully Human Monoclonal Antibody from A ntibody Secreting Cells after 

Vaccination with Pneumovax®23 are SerotypeSpecific and Facilitate Opsonophagocytosis. Immunobiology; 218(5): 745–754. doi:10.1016/j.imbio.2012.08.278. 

 

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