Reduced Rate of Disease Development After HIV-2 Infection as Compared to HIV-1

Abstract

Human immunodeficiency virus type-2 (HIV-2) is a close relative of the prototype acquired immunodeficiency syndrome (AIDS) virus, HIV-1. HIV-2 is biologically similar to HIV-1, but information is lacking concerning clinical outcomes of HIV-2-infected individuals. From 1985 to 1993, a prospective clinical study was conducted in women with HIV-2 and HIV-1 infection to determine and compare rates of disease development. HIV-1-infected women had a 67% probability of AIDS-free survival 5 years after seroconversion in contrast with 100% for HIV-2-infected women. In addition to having significantly less HIV-related disease outcome in HIV-2 enrollees compared to HIV-1 enrollees, the rate of developing abnormal CD4+ lymphocyte counts with HIV-2 infection was also significantly reduced. This natural history study demonstrates that HIV-2 has a reduced virulence compared to HIV-1.

Synonymous Substitution Rates Predict HIV Disease Progression as a Result of Underlying Replication Dynamics

“…Individual patient numbers from Shankarappa et al [14] are shown in circles, and progression times for each patient are indicated in italics. doi:10.1371/journal.pcbi.0030029.g002 other hand, is known to be less transmissible and less pathogenic than HIV-1 group M [34,35]. The two HIV-1 group O datasets had dS rates that were similar to the rates estimated for HIV-1 subtype B moderate progressors (Table 2).…”

“…Therefore, these findings seem to resolve the longstanding issue of the nonpathogenic nature of SIV infection. In addition, it provides an explanation for the lower pathogenicity of HIV-2 infections [35] and the generally low HIV-2 synonymous substitution rates observed in this study. Nef-mediated TCR-CD3 down-modulation also correlated with CD4þ T cell depletion in SIVsmm infected sooty mangabeys [45].…”

The Glutamine-rich Region of the HIV-1 Tat Protein Is Involved in T-cell Apoptosis

“…Some studies have reported that disease progression is more rapid in Africa (1-3), but others contest this view (4,5). In Uganda, a study has demonstrated that the time from seroconversion to death is very similar to that reported for patients in industrialized countries prior to the introduction of anti-retroviral therapy (6).…”

Apoptosis in SIV infection

“…Thus, HIV-2 is characterized by higher CD4 counts, low level of viremia, and low transmission rate. 54 It has been reported that the low pathogenicity of HIV-2 is associated with a lower immune activation and a lesser degree of CD4 T-cell apoptosis. 55 Importantly, the magnitude of CD4 þ T-cell apoptosis observed in HIV-infected individuals correlates well with the stage of HIV disease.…”