Background: HIV-1 groups M and O co-circulate in Cameroon and dual infections as well as HIV-1 M/O intergroup recombinant viruses have been reported in some patients. Recent data has described infection with HIV-1 M/O intergroup recombinant virus in the absence of dual infections thereby suggesting a direct transmission of the recombinant virus. In this study, we described and characterized an HIV-1 M/O intergroup recombinant virus in the absence of dual infection in a couple living in Cameroon. Here we provide for the first time evidence of a direct transmission of an HIV-1 M/O intergroup recombinant virus from one person to another.
Methods: Consecutive samples were obtained from a couple presenting for routine HIV viral load analysis. Prior to viral load analysis, each sample was subjected to HIV serotyping using envelope (V3 and gp41) peptides. These samples were subsequently screened for the presence of potential recombinant virus using specific PCRs targeting the Protease (PROT), Reverse transcriptase (RT), Integrase (INT) and envelope (gp41) genes of HIV-1 groups M and O. The previously reported recombination hotspot in the vpr gene was investigated using RT- nested PCRs. Near full length genome sequences of the viruses detected in both spouses were determined by amplification and sequencing of seven partially overlapping sub-genomic regions. Phylogenetic and similarity profile analyses were performed to investigate the genetic relatedness between viruses from both spouses.
Results: HIV serotyping indicated that samples from both patients (husband and wife) were reactive only with HIV-1 group O peptides thereby suggesting an infection with HIV-1 group O virus in both spouses. Molecular tests identified HIV-1 group M in the polymerase (PROT, RT and INT) and HIV-1 group O in the envelope (gp41) regions respectively. These results were consistent with phylogenetic analyses of corresponding sub-genomic regions. Altogether, phylogenetic analysis and similarity profile of the near full length genome sequences showed that both spouses were infected with a unique recombinant virus (M/O) having its recombination breakpoint in the vpr gene.
Conclusions: In this study, we observed for the first time that HIV-1 M/O intergroup recombinant viruses could be transmitted from one person to another. The genetic diversity and public health importance of transmitting these recombinant viruses in such areas where both viruses (HIV-1 groups M and O) are endemic cannot be overemphasized.
Figure 1: Recombination analyses of REC003 (Husband ; accession no KM438031) and REC024 (Wife; accession no KM438032) viruses
Near full-length genomes of REC003 (9135bp; blue line) and REC024 (9176bp; dark line) were compared each other and with the closest strains of HIV-1 group M (suptype F2; green line) and HIV-1 group O (red line) identified by HIV BLAST. The viruses exhibit a mosaic structure M-O with the gag-pol portion belonging to HIV-1 M and the env portion belonging to HIV-1 O. Both viruses defined the same patterns along the entire genome.