Influence of N-linked glycosylation of minor proteins of porcine reproductive and respiratory syndrome virus on infectious virus recovery and receptor interaction

It has been proposed that the N-linked glycan of the minor proteins of porcine reproductive and respiratory syndrome virus (PRRSV) is important for the production of infectious virus. In this study, we showed that N-linked glycosylation of GP2 is not essential for virus viability and none of the individual glycosylation sites in GP3 has a vital effect on the production of infectious virus. Moreover, mutations of single and double glycosylation sites in GP4 are not critically important for infectious virus recovery, triple and quadruple mutations are lethal. The bimolecular fluorescence complementation (BiFC) analysis also showed that GP4, but might be not GP2, is involved in interaction with cellular receptor CD163 and that glycosylation of GP4 might not play a vital role in the interaction with CD163. The study further revealed that none of the N-glycosylation sites in the minor proteins is critical for the susceptibility of mutants to neutralizing antibody.