Population dynamics of HIV-2 in rural West Africa: comparison with HIV-1 and ongoing transmission at the heart of the epidemic.

Journal article

OBJECTIVES: To compare the population dynamics of HIV-2 and HIV-1, and to characterize ongoing HIV-2 transmission in rural Guinea-Bissau. DESIGN: Phylogenetic and phylodynamic analyses using HIV-2 gag and env, and HIV-1 env sequences, combined with epidemiological data from a community cohort. METHODS: Samples were obtained from surveys in 1989-1991, 1996-1997, 2003 and 2006-2007. Phylogenies were reconstructed using sequences from 103 HIV-2-infected and 56 HIV-1-infected patients using Bayesian Evolutionary Analysis by Sampling Trees (BEAST), a relaxed molecular clock and a Bayesian skyline coalescent model. RESULTS: Bayesian skyline plots showed a strong increase in the 1990s of the HIV-1 effective population size (Ne) in the same period that the Ne of HIV-2 came into a plateau phase. The population dynamics of both viruses were remarkably similar following initial introduction. Incident infections were found more often in HIV-2 transmission clusters, with 55-58% of all individuals contributing to ongoing transmission. Some phylogenetically linked sexual partners had discordant viral loads (undetectable vs. detectable), suggesting host factors dictate the risk of disease progression in HIV-2. Multiple HIV-2 introductions into the cohort are evident, but ongoing transmission has occurred predominantly within the community. CONCLUSION: Comparison of HIV-1 and HIV-2 phylodynamics in the same community suggests both viruses followed similar growth patterns following introduction, and is consistent with the hypothesis that HIV-1 may have played a role in the decline of HIV-2 via competitive exclusion. The source of ongoing HIV-2 transmission in the cohort appears to be new HIV-2 cases, rather than the pool of older infections established during the early growth of HIV-2.

Authors: de Silva, T; van Tienen, C; Onyango, C; Jabang, A; Vincent, T

• Publication status: Published
• Journal: AIDS (London, England)
• Volume: 27
• Issue: 1
• Pages: 125-134
• Publication date: 2013-01-01
• DOI: 10.1097/qad.0b013e32835ab12c
• EISSN: 1473-5571
• ISSN: 0269-9370
• Language: English
• Keywords: HIV Infections; Humans; Cluster Analysis; Bayes Theorem; Rural Population; Sexual Partners; gag Gene Products, Human Immunodeficiency Virus; HIV-2; Guinea-Bissau; HIV-1; env Gene Products, Human Immunodeficiency Virus; Phylogeny; Male; Middle Aged; Female