Nigerian HIV Type 2 Subtype A and B from Heterotypic HIV Type 1 and HIV Type 2 or Monotypic HIV Type 2 Infections

Abstract

The presence of HIV-2 in Nigeria has been confirmed serologically, but not genetically. To determine the frequency of HIV-2 infections and the dynamics between HIV-1 and HIV-2 in 35 of 36 Nigerian states, 420 blood samples were collected in 1999. Antibodies to HIV-1 and HIV-2 were detected by EIA and seroreactivity was confirmed with the INNO-LIA HIV Line Assay. The frequency of HIV-2 was 4.3% (18 of 420), with 3.8% (16 of 420) HIV-1 and HIV-2 (HIV-1/2) heterotypic and 0.5% (2 of 420) HIV-2 homotypic infections. The presence of HIV-2 subtype B in the two monotypic HIV-2 infections and subtype A in 11 (68.8%) of 16 HIV-1/2 dually seropositive samples was established by sequencing and phylogenetic analysis. HIV-2 subtype B viruses were not found in any of the HIV-1/2 dual infections, and HIV-2 subtype A strains were not identified in either of the two monotypic HIV-2 infections. Since our sample size was small and represented only convenience samples, larger randomized studies will be needed to better understand the dynamics of infection between HIV-1 and different HIV-2 subtypes and to determine whether significant biological differences exist among the HIV- 2 subtypes.

Simian Immunodeficiency Virus Infection in Free-Ranging Sooty Mangabeys ( Cercocebus atys atys ) from the Taï Forest, Côte d'Ivoire: Implications for the Origin of Epidemic Human Immunodeficiency Virus Type 2

“…In the case of HIV-1, infections with groups N and O have been largely confined to Gabon and Cameroon (4,5,42), while group M has spread pandemically (51,52). In the case of HIV-2, groups A and B have infected substantial numbers of people in west Africa (17,23,34,54,79), while groups C to H have each been identified only in single individuals (14,18,22,76). Circumstances that favored cross-species transmission and subsequent amplification of only a subset of these viruses are unknown but have implications for potential future SIV transmissions.…”

Absence of routine molecular testing and prevalence of HIV-2 infection in regions hardest-hit by HIV infection

“…In 1996 an HIV-2-specific antibody was detected in 4.5% of samples collected in six regions of the country (Lagos, Cross River, Borno, Kano, and Jigawa states) [18]. The prevalence of HIV-2 in blood samples collected from 35 out of 36 states in Nigeria was found to be 4.3% in 1999 [3]. These studies show that HIV-2 is more prevalent in sexually active populations.…”

“…These studies show that HIV-2 is more prevalent in sexually active populations. However, studies conducted after 1994 [3,18] suggest that HIV-2 viral strains are widespread in Nigeria and are not restricted to specific sub-populations. As such, patients whose HIV-1 test results are inconsistent with clinical findings should be considered for the possibility of HIV-2 seropositivity.…”

“…This study confirms the results of other studies that show that HIV-2 homotypic infections in Nigeria are extremely rare. HIV-2 is usually found together with HIV-1 [3], which suggests that HIV-2 may have evolved as a "cheater" virus that may not be suitably adapted to infect the Nigerian population and exists more often in unison with HIV-1 for survival purposes [20]. Also, the FSWs have multiple HIV exposures that may result in superinfection with different HIV types or subtypes, which would lead to a greater chance of acquiring HIV-1 and HIV-2 co-infections and a Using molecular testing, our study revealed that 1.9% of samples classified as negative were indeed positive.…”

“…National sentinel surveillance showed significant regional variation, from 1% in Ekiti State in the southwest zone to 10.6% in Benue State in the northcentral zone [1]. The first case of HIV/AIDS in Nigeria was diagnosed in 1986; since then, confirmed cases of HIV-1 and HIV-2 have been reported [2,3]. HIV-1 and HIV-2 are genetically similar but have very distinct epidemiologies [4].…”