Correlates of protective immunity against HIV-1 infection in immunized chimpanzees

Several experimental vaccination strategies have been developed to prevent primary infection with human immunodeficiency virus (HIV), and as immunotherapeutics for infected individuals. Many of the putative vaccines have been tested in chimpanzees (p. troglodytes) to determine their safety, efficacy, and to delineate immune correlates of protection. To date, approximately 25 candidate vaccines representing active or passive strategies have been evaluated in chimpanzees, and efficacy has been based on protection against primary infection following intravenous or mucosal challenge with cell-free or cell-associated virus. Active immunization has been attempted with whole inactivated virus, envelope depleted viral preparation, vaccinia vector expressing gp 160 in combination with other viral gene products, and subunit vaccines containing recombinant gp 120 derived from different isolates. Polyclonal and monoclonal antibodies with neutralizing activity have been utilized for pre- and post-exposure passive immunization to block primary infection with HIV.