Human immunodeficiency virus type 1 variability and long-term non-progression

A high heterogeneity is found in the HIV-1 genome in vivo, not only between individuals, but also within a single individual. Different types of genet ic heterogeneity of HIV-1 can be analyzed: the extension and the evolution of the viral quasispecies in blood, the variation between the virus obtaine d from different body compartment, the differences between isolates from di verse individuals and between HIV-1 subtypes. The virus population during p rimary HIV-1 infection is generally homogeneous and the intrahost viral evo lution is thought to be forced (in absence of antiviral therapy) by the imm une system pressure and is generally related to the length of the immunocom petent period. A group of 12 Italian and Swedish well characterized HIV-1 infected long-te rm nonprogressors (LNTP) have been analyzed for the viral heterogeneity, ca lculated in the nef gene and in the long terminal repeat (LTR). The intra-s ample variations in LTNP were found comparable with those from 8 progressor patients, while a lower inter-individual diversity was observed in the for mer. In one LTNP the viral evolution during a four-years period was extreme ly low suggesting that other factors than the host immune pressure may be i nvolved in modulating the intra- and inter-sample HIV-1 diversity.