Predominance of infection with HIV-1 circulating recombinant form CRF02_AG in major Cameroonian cities and towns.

Abstract

The HIV-1 epidemic in Cameroon is characterized by extensive genetic variability in terms of the co-circulation of representatives of the three main groups: M (major), O (outlier), and N (non-M, non-O) [1–10]. Analysis of HIV-1 group M subtypes in Cameroon has revealed the presence of virtually all genetic subtypes and circulating recombinant viruses CRF01_AE and CRF02_AG, as well as a variety of other intersubtype recombinants. Most studies identifying HIV-1 clades in Cameroon have been focused on two major cities, including Yaounde and Douala, showing that CRF02_AG and subtype A are the predominant HIV-1 group M infections in Cameroon, accounting for approximately 50–65% of HIV-1 infections. So far information on the proportion of group M clades infecting individuals in other cities and towns in different provinces in Cameroon is scarce [4,10]. In the present study, we have examined the HIV-1 group M clade distribution among HIV-1 seropositive plasma samples, taken between January and July 1999, in seven big cities/towns in five provinces in Cameroon. Starting from the plasma, 112 out of 198 samples were processed successfully using reverse transcriptase–polymerase chain reaction (RT–PCR) for amplification of parts of gag and env. RNA extractions, one-tube RT–PCR and nested PCR were performed as described elsewhere [3]. Subtyping was performed by gag heteroduplex mobility assay (HMA) [3] and env HMA [11]. When subtype determination by HMA was not definitive, the C2V3 for env and part of p24 for gag were amplified, sequenced and phylogenetically analysed. The cities/towns and the numbers of samples documented include Yaounde (n = 15) and Bafia (n = 15) in Centre province, Douala (n = 11) in Littoral province, Bamenda (n = 51) in North West province, Tiko (n = 4) and Limbe (n = 6) in South West province, and Ngaoundere (n = 10) in Adamaoua province. The samples were obtained from both symptomatic and asymptomatic patients and similar numbers of men and women. Both gag and env subtype information was obtained for 88 out of 112 (78.6%) samples. In addition, gag and env subtype information was obtained from 10 and 14 samples, respectively (Table 1). Eighty-nine out of 98 (90.1%) of the Cameroonian samples were either subtype A or CRF02_AG, as subtyped by env HMA, whereby differentiation between subtype A and CR F02_AG was not possible. These isolates were classified by gag HMA as follows: 62 (63.3%) CR F02_AG, 13 (13.3%) subtype A, one (1%) CRF01_AE, two (2%) subtype G, and one (1%) unclassified. Overall, 86 of the 102 (84.3%) samples with gag subtype information were clade A or CRF02_AG. By parallel gag and env subtyping, the subtype distribution of the remaining nine samples was as follows: three subtype D, one subtype F (F2), two subtype G, and one each of intersubtype recombinants A/CRF01_AE, A/F2, and F2/J (Table 1).Table 1: HIV-1 group M clades in major cities and towns of Cameroon. Our observations add to previous results on molecular epidemiology in different provinces in Cameroon, demonstrating a high prevalence of CRF02_AG and subtype A, accounting for 90% of circulating HIV-1 strains [5]. The country-wide high prevalence of HIV-1 CRF02_AG in Cameroon compared with the relatively low prevalence of CRF02_AG in the Democratic Republic of Congo [12] suggest an early founder effect of this AG recombinant in West Central Africa initiating major CRF02 epidemics [3,9]. Phillipe Nyambia Leo Heyndrickxb Katleen Vereeckenb Sherri Burdaa Kathleen De Houwerbc Sandra Coppensbc Mateusz Urbanskia Constance Williamsa Peter Ndumbed Wouter Janssensbc