Influenza specific antibody-mediated and complement-dependent cellular cytotoxicity inducing antibodies in vaccinated and infected pigs

Renukaradhya J Gourapura^1*Mithilesh Singh¹Gabriela Mansano Do Nascimento²Sankar Renu¹Dina Bugybayeva¹Comfort Olaitan Comfort¹Raksha Suresh¹Jennifer Schrock¹Sara Dolatyabi¹Diego G. Diel²Prosper N Boyaka¹

• ¹The Ohio State University, Columbus, United States
• ²Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States

In addition to neutralizing activity, antibodies can contribute to protection against viral infections through antibody-dependent cellular cytotoxicity (ADCC) and antibody-mediated complement-dependent cell cytotoxicity (CDC) mediated via Fcy-receptors. Swine is a suitable large animal biomedical model for influenza research, because it is a natural host for influenza like humans exhibiting comparable clinical and immunological responses. Unfortunately, there are currently limited insights about ADCC and CDC functions to swine influenza A virus (SwIAV) in pigs due to lack of adequate immunological tools. Using MDCK cells expressing SwIAV hemagglutinin (HA) protein, we optimized ADCC and CDC assays to evaluate cytotoxicity mediated by virus specific swine antibodies. Using these assays, we quantified and compared the antibody-mediated cytotoxicity induced in pigs by intranasal chitosan nanoparticle based inactivated monovalent whole SwIAV vaccine and intramuscular administered commercial multivalent SwIAV vaccine. Our results revealed that in SwIAV maternal antibody positive pigs following vaccination with whole inactivated virus failed to elicit specific ADCC mediating antibodies, but production of CDC antibodies was not affected. However, after exposure of vaccinated animals to challenge infection high levels of ADCC antibodies were elicited. In addition, depending on the route of vaccination and type of inactivated SwIAV vaccine (mono vs multivalent) with adjuvant formulation detected highly variable levels of virus neutralizing and non-neutralizing antibody functions. Overall, we observed a positive trend among the magnitude of ADCC, CDC, antibody avidity, NAbs and HAI antibody responses in vaccinated and influenza virus infected pigs. In conclusion, measuring ADCC and CDC mediating antibodies in pigs is important for evaluating the protective immunity against influenza by vaccines. Monitoring the function of both virus neutralizing and non-neutralizing antibodies in vaccinated animals aid in the development of innovative cross protective vaccine formulations to fight against constantly evolving influenza viruses.