CD4 and HIV-1 infection: The extent to which the dual tropic nature of the infecting virus in the low immune activator (LIA) patient may have influenced the overall burden of HIV-1 infection in the GALT and subsequent levels of immune activation in that compartment (given that the preferred targets for HIV-1 infection are believed to be mucosal CCR5+ memory CD4+ T cells [20], [27], [28]) is unclear.