Passively administered neutralizing serum that protected macaques against infection with parenterally inoculated pathogenic simian-human immunodeficiency virus failed to protect against mucosally inoculated virus

Macaques inoculated orally, vaginally, or parenterally with SHIVKU-1 develo p severe systemic infection, acute loss of CD4(+) T cells, and AIDS. We sho wed in a previous report that passive immunization with neutralizing serum protected macaques against infection with parenterally inoculated pathogeni c SHIV given 24 hr later. In the study reported here we asked whether the i dentical passive immunization protocol would protect macaques against infec tion with pathogenic SHIV following oral inoculation of the virus. Ten pigt ail macaques were inoculated orally with one animal infectious dose of SHIV KU-1 Four of the 10 had been given pooled anti-SHIV plasma (15 ml/kg) 24 hr earlier, 4 others were given the same dose of anti-SHIV plasma 2 hr after virus challenge, and the 2 remaining animals were used as controls. The neu tralizing antibodies failed to protect macaques against infection after muc osal challenge with SHIVKU-1.