CD4 and HIV-1 infection: Although researchers have proposed either antibodies or T cells as the most effective means to elicit protective immunity, a central theme of HIV-1 vaccine design now is to elicit coordinated antiviral CD8+ cytotoxic T lymphocytes (CTL) to control HIV-1 infection and CD4+ T cells that help induce and maintain CD8+ and B cell responses [44]–[46].