Multiple Presence and Heterogeneous Distribution of HIV-1 Subtypes in Nigeria

Abstract

Human immunodeficiency viruys type I (HIV) subtypes circulating in Nigeria was determined by using the Peptide based Enzyme Immuno-Assay (PELISA) to analyze sera or plasma samples collected from 925 individuals with ELISA and Western blot confirmed HIV-I infection in the three broad geographical regions (southwestern, southeastern and northern) of Nigeria.  The synthetic peptides used as the capture antigens in the PELISA were designed from the consensus sequence of the third hypervariable region.

(V3 loop) of HIV-1 subtypes A, B, C, D, E and O of HIV-1.  The assay was initially validated using plasma samples from individuals infected with various genetically identified HIV-1 subtypes in Europe andAfrica.  Any serum or plasma sample that reacted with more than one peptide was re-tested using the same antigen panel in a limiting ELISA technique.

The result co-circulation of multiple HIV-1 subtypes including A, B, C, D, E, and O inNigeria.  Varying prevalence of specific antibodies to the six HIV-1 subtypes included in the PELISA panel were detected among infected individuals inNigeria.  Subtype C was the most prevalent, 48.3% (447) followed by A = 19.8% (183), D = 9.5% (88), E = 8.4% (74), B = 2.5% (23) and group O, 2.4% (20).  Thirty-six (3.9%) of the samples tested were dually reactive while 52 (5.6%) did not react with any of the six HIV-1 subtype peptides included in the assay.  A heterogeneous distribution of at least 5 HIV-1 subtypes was observed in all the regions with subtype C being the most prevalent in all the locations, states and regions, followed by subtypes A, D and E.  None of the samples from the northern and southeastern regions reacted with HIV-1 subtype O and B peptides respectively.

As far as it can be ascertained, this is the first report of detection of HIV-1 subtypes B, D and E inNigeria.  Furthermore, the result of this work indicates widespread circulation of multiple HIV-1 subtypes inNigeria.  Therefore a polyvalent vaccine will be the best option for effective prophylactic immunization against HIV-1 infection inNigeria.