The neutralization of pseudorabies virus by anti-alpha-galactocyl natural antibody in normal serum

Pseudorabies virus (PrV), a member of herpesviridae alphaherpes subfamily, can infect human cells in vitro. However, the transmission to Old World primates including humans is strongly restricted. In this study, we report the neutralizing activity of normal human serum against PrV grown in CPK cells derived from pig. PrV grown in all Old World primates-derived cells, which was tested in this study, were not neutralized by normal human serum. The virion of PrV grown in CPK cells harbored Galalpha1-3Galbeta1-4GlcNAc-R (alpha-gal epitope) on its surface, while PrV grown in Vero cells did not. Depletion of antibodies reacting to surface antigens of CPK cells negated the neutralization activity of human serum. Blockade of anti-alpha-gal antibodies by adding soluble Galalpha1-3Gal to normal human serum also prevent the inactivation of PrV grown in CPK cells. Although normal swine serum did not neutralize PrV grown in CPK cells, swine serum supplemented with exogenous anti-alpha-gal antibodies did. These results indicate that anti-alpha-gal antibodies in normal human serum contribute to the neutralization of PrV. Anti-alpha-gal antibodies in normal human serum may prevent transmission of PrV into humans.