CD4 and AIDS: DSS treatment of chronically SIV-infected AGMs, a natural host species for SIV in which infection does not induce excessive immune activation and inflammation and typically does not progress to AIDS, demonstrated that superimposed DSS-induced GI tract damage with resultant microbial translocation may be sufficient to drive systemic inflammation/immune activation, which augmented viral replication and mucosal CD4 T-cell depletion.