COOPERATION BETWEEN TRANSMISSIBLE GASTROENTERITIS CORONAVIRUS (TGEV) STRUCTURAL PROTEINS IN THE IN-VITRO INDUCTION OF VIRUS-SPECIFIC ANTIBODIES

Following infection of haplotype defined NIH-miniswine with virulent t ransmissible gastroenteritis coronavirus (TGEV), isolated mesenteric l ymph node CD4(+) T-cells mounted a specific proliferative response aga inst infectious or inactivated purified virus in secondary in vitro st imulation. A specific, dose-dependent response to the three major reco mbinant viral proteins: spike (S), membrane (M), and nucleoprotein (N) , purified by affinity chromatography, was characterized. Induction of in vitro antibody synthesis was analysed, The purified recombinant vi ral proteins induced the in vitro synthesis of neutralizing TGEV-speci fic antibodies when porcine TGEV-immune cells were stimulated with eac h of the combinations made with two of the major structural proteins: S + N, S + M, and to a minor extent with M + N, but not by the individ ual proteins. S-protein was dissociated from purified virus using NP-4 0 detergent and then micellar S-protein oligomers (S-rosettes) were fo rmed by removing the detergent. These occurred preferentially by the a ssociation of more than 10 S-protein trimmers. These S-rosettes in col laboration with either N or M-proteins elicited TGEV-specific antibodi es with titers up to 84 and 60%, respectively, of those induced by the whole virus. N-protein could be partially substituted by a 15-mer pep tide that represents a T helper epitope previously identified in N-pro tein (Anton et al. (1995)). These results indicate that the induction of high levels of TGEV-specific antibodies requires stimulation by at least two viral proteins, and that optimum responses are induced by a combination of S-rosettes and the nucleoprotein. Copyright (C) 1996 El sevier Science B.V.