Induction of mucosal antibody responses by microsphere-encapsulated formalin-inactivated simian immunodeficiency virus in a male urethral challenge model

Male rhesus macaques were immunized mucosally with microsphere-encapsulated formalin-inactivated simian immunodeficiency virus (SIV) particles in a te st of immunogenicity and protection against mucosal SN challenge. Tracheal boosting of animals that had been primed intramuscularly resulted in strong serum ELISA titers to SIV, and evidence of local IgA responses in broncho- alveolar washes. The bulk of the antibody response was against non-envelope epitopes. No neutralizing antibody was observed, and intraurethral challen ge with cell-free rhesus-grown virus showed no evidence of protection again st infection. Microsphere-based immunization efficiently raises local and s ystem responses, but the resulting immunity to SIV is apparently not suffic ient to protect against mucosal challenge. (C) 1999 Elsevier Science Ltd. A ll rights reserved.