Natural killer (NK) cell antibody-dependent cell-mediated cytotoxicity (ADCC) to the coronavirus OC-43 9107

Abstract Description ADCC can eliminate cells infected with enveloped viruses and can do so at antibody concentrations far below the concentrations needed for viral neutralization. For ADCC to occur, there must be (1) sufficient external viral antigens in the membranes of infected cells and (2) sufficient antibodies these antigens. We investigated if these two requirements occur for the endemic coronavirus OC-43 using NK-92-CD16A effector cells, OC-43 virus from BEI, 51Cr-labeled infected A549 cells, humanized anti-S (spike) protein mAbs and plasma from 12 children who had respiratory infections with OC-43. PCR of the supernatants of virally infected cells indicated that that there was production release of OC-43 virions by day 2 post infection. By immunofluorescent staining with mouse mAbs anti-S, we observed external membrane OC-43 antigens on days 2 & 3 post infection. Plasma antibodies generated stronger fluorescent signals than the mAbs. Antibody binding was greater on day 3 than day 2. ADCC was detectable only starting on day 3 and only with the plasma polyclonal antibodies from the patients, not with the humanized anti-S mAbs. We interpret these data to indicate that OC-43 virally infected cells have external viral proteins to support ADCC and that plasma post infections have sufficient antibodies to support ADCC to OC-43. Also, the time of appearance of viral proteins in plasma membranes may affect ADCC anti-viral efficacy. Funding Sources UNR Foundation C.E. Hudig Fund Topic Categories Viral Immunology (VIR)