Mechanism of antibody-mediated protection against herpes simplex virus infection in athymic nude mice: requirement of Fc portion of antibody.

Experiments were performed to investigate the resistance of the host due to antibody-mediated mechanisms to herpes simplex virus (HSV) infection. Transfer of hyperimmune anti-HSV mouse serum inhibited the development of skin lesions and prolonged the survival of lethally HSV-infected nude mice. Relatively high concentrations of antibody were required to achieve this protection. Antisera prepared in heterologous animals were also effective, while administration of anti-cowpox virus serum or interferon provided no protection. This type of protection is therefore due to specific antibody and cannot be attributed to interferon. In order to delineate the requirement for antibody in antibody-mediated protection, human gamma globulin preparations were transferred to lethally HSV-infected nude mice. Transfer of intact human gamma globulin (GG) was effective in controlling infection. S-sulfonation of GG did not diminish the protective ability. However, purified F(ab')2 did not have any protective action even when it was administered frequently to maintain serum neutralizing antibody titer. GG was effective in C5-deficient mice lethally infected with HSV. These results indicate that in vivo antibody-mediated protection to HSV infection requires the Fc region of the intact IgG molecule and suggest that antibody-dependent cell-mediated cytotoxicity may be operative in vivo.