HIV-1 CRF09_cpx circulates in the North West Province of Cameroon where CRF02_AG infections predominate and recombinant strains are common.

This study describes the HIV-1 genetic diversity that currently circulates in Bamenda, the provincial capital of the North West province of Cameroon. Phylogenetic analysis of the protease (pro) gene of 20 HIV-1-seropositive individuals identified 11 (55%) CRF02_AG, one D, one F2, one J, and four (20%) unclassifiable strains. Interestingly, the remaining two (10%) samples, 02CMNYU3072 and 03CMNYU3224, originating from epidemiologically unlinked individuals, were classified as CRF09_cpx, representing the first reported cases of this complex circulating recombinant form (CRF) in Cameroon. Additional analysis of the C2V5 portion of the envelope (env) gene confirmed the CRF09_cpx identity of these isolates and classified the remaining isolates as CRF02_AG (n = 12, 63%), subtype D (n = 2, 11%), subtype F2 (n = 2, 11%), and subtype A1 (n = 1). In combination, the pro and env subtyping results revealed three (16%) isolates with discordant subtypes including J( pro )CRF02_AG( env ), CRF02_AG( pro )D( env ), and CRF02_AG( pro )F2( env ). In conclusion, this study highlights the presence of HIV-1 CRF09_cpx in Cameroon and identifies three possible intersubtype recombinants (ISRs) containing CRF02_AG in a town where CRF02_AG infections predominate, and stresses the commonness of HIV-1 recombinant strains in a region where broad genetic diversity exists.