CD4 and infection: Thus, induction of effective anti-Tat Abs may represent a pathogenesis-driven therapeutic intervention to block disease progression as indicated by the effects of long-lasting, high titers anti-Tat Abs in natural infection [9, 79] or after vaccination with Tat, which induced CD4+ T cell recovery, immune restoration, as well as reduction of immunoactivation and of proviral DNA in Italian subjects (ISS T-002 trial) [53, 57].