Lower Human Immunodeficiency Virus (HIV) Type 2 Viral Load Reflects the Difference in Pathogenicity of HIV‐1 and HIV‐2

Abstract

Human immunodeficiency virus type 2 (HIV-2) is less pathogenic than HIV type 1 (HIV-1), but the mechanisms underlying this difference have not been defined. We developed an internally controlled quantitative reverse transcriptase-polymerase chain reaction to measure HIV-2 viral load and determined levels of plasma virus in a cohort of registered commercial sex workers in Dakar, Senegal. The assay has a lower limit of detection of 100 copies/mL and is linear over 4 logs. HIV-2 viral RNA was detectable in 56% of all samples tested; the median load was 141 copies/mL. Levels of viral RNA in the plasma were inversely related to CD4+ cell counts. HIV-2 and HIV-1 viral loads were compared among the seroincident women in the cohort; the median viral load was 30x lower in the HIV-2-infected women (P<.001, Wilcoxon rank sum test), irrespective of the length of time infected. This suggests that plasma viremia is linked to the differences in the pathogenicity of the 2 viruses.

CD8+ T cell responses to human immunodeficiency viruses type 2 (HIV‐2) and type 1 (HIV‐1) gag proteins are distinguishable by magnitude and breadth but not cellular phenotype

“…Most HIV-2 + individuals are long-term nonprogressors (LTNP) with low or undetectable viral loads [1,2]. Therefore, HIV-2 infection has the features of an 'attenuated' HIV-1 infection, but evidence for a true attenuated phenotype is lacking [3].…”

Tracing the origin and history of the HIV-2 epidemic

“…Whereas HIV-1 group M subtypes (A-D, F, H, J, and K) are spread globally, HIV-2 subtypes are mainly restricted to West Africa and can be categorized as epidemic subtypes (A and B) and nonepidemic subtypes (C-G) (4)(5)(6)(7). Biological reasons have been invoked to explain the difference in global epidemiology between HIV-1 and HIV-2, such as lower HIV-2 viral loads that correlate with a lower transmissibility (8)(9)(10). However, attempts to compare the history of the epidemics at their respective geographic origins are still lacking.…”

Epidemiology of Human Immunodeficiency Virus in Prospective Blood Donors and Testing Algorithm Assessment with Real-Time PCR for Optimal Blood Safety Practice

“…Again, it might mean that this particular VBD was positive for HIV-2 which is less virulent and have lower progression to AIDS compared to HIV-1 [12]. Studies have showed the inverse relationships between HIV viral loads and CD4+ T-lymphocytes [45,46]. DOR adopted in this study validated the reliability of the results of rapid antibody techniques (based on serial algorithm II).…”