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. 2011 Apr 23:8:185.
doi: 10.1186/1743-422X-8-185.

Identification of new, emerging HIV-1 unique recombinant forms and drug resistant viruses circulating in Cameroon

Viswanath Ragupathy  1 , Jiangqin Zhao, Owen Wood, Shixing Tang, Sherwin Lee, Phillipe Nyambi, Indira Hewlett
Affiliations

Identification of new, emerging HIV-1 unique recombinant forms and drug resistant viruses circulating in Cameroon

Viswanath Ragupathy et al. Virol J. .

Abstract

Background: The HIV epidemic in Cameroon is characterized by a high degree of viral genetic diversity with circulating recombinant forms (CRFs) being predominant. The goal of our study was to determine recent trends in virus evolution and emergence of drug resistance in blood donors and HIV positive patients.

Methodology: Blood specimens of 73 individuals were collected from three cities and a few villages in Cameroon and viruses were isolated by co-cultivation with PBMCs. Nested PCR was performed for gag p17 (670 bp) pol (840 bp) and Env gp41 (461 bp) genes. Sequences were phylogenetically analyzed using a reference set of sequences from the Los Alamos database.

Results: Phylogenetic analysis based on partial sequences revealed that 65% (n = 48) of strains were CRF02_AG, 4% (n = 3) subtype F2, 1% each belonged to CRF06 (n = 1), CRF11 (n = 1), subtype G (n = 1), subtype D (n = 1), CRF22_01A1 (n = 1), and 26% (n = 18) were Unique Recombinant Forms (URFs). Most URFs contained CRF02_AG in one or two HIV gene fragments analyzed. Furthermore, pol sequences of 61 viruses revealed drug resistance in 55.5% of patients on therapy and 44% of drug naïve individuals in the RT and protease regions. Overall URFs that had a primary HIV subtype designation in the pol region showed higher HIV-1 p24 levels than other recombinant forms in cell culture based replication kinetics studies.

Conclusions: Our results indicate that although CRF02_AG continues to be the predominant strain in Cameroon, phylogenetically the HIV epidemic is continuing to evolve as multiple recombinants of CRF02_AG and URFs were identified in the individuals studied. CRF02_AG recombinants that contained the pol region of a primary subtype showed higher replicative advantage than other variants. Identification of drug resistant strains in drug-naïve patients suggests that these viruses are being transmitted in the population studied. Our findings support the need for continued molecular surveillance in this region of West Central Africa and investigating impact of variants on diagnostics, viral load and drug resistance assays on an ongoing basis.

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Figures

Figure 1
Figure 1
Samples for this study were collected from Bamenda, Buea and Limbe in Cameroon are indicated with an asterisk (*).
Figure 2
Figure 2
The Pie diagram shows the distribution of pure HIV subtypes and URFs. Discordant subtypes of URFs in the gag (p17), pol and Env (gp41) are indicated in the table.
Figure 3
Figure 3
Figure 3A and 3B are histogram representations of the average HIV-1 p24 levels of CRF02_AG and URFs in cell culture studies.
See this image and copyright information in PMC

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