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Evolution and molecular epidemiology of subtype C HIV-1 in Zimbabwe.

ABSTRACT: To investigate the origins and evolutionary history of subtype C HIV-1 in Zimbabwe in a context of regional conflict and migration.HIV-1C pol sequence datasets were generated from four sequential cohorts of antenatal women in Harare, Zimbabwe sampled over 15 years (1991-2006).One hundred and seventy-seven HIV-1C pol sequences were obtained from four successive cohorts in Zimbabwe. Maximum-likelihood methods were used to explore phylogenetic relationships between Zimbabwean HIV-1C sequences and subtype C strains from other regions. A Bayesian coalescent-based framework was used to estimate evolutionary parameters for HIV-1C in Zimbabwe, including origin and demographic growth patterns.Zimbabwe HIV-1C pol demonstrated increasing sequence divergence over the 15-year period. Nearly all Zimbabwe sequences clustered phylogenetically with subtype C strains from neighboring countries. Bayesian evolutionary analysis indicated a most recent common ancestor date of 1973 with three epidemic growth phases: an initial, slow phase (1970s) followed by exponential growth (1980s), and a linearly expanding epidemic to the present. Bayesian trees provided evidence for multiple HIV-1C introductions into Zimbabwe during 1979-1981, corresponding with Zimbabwean national independence following a period of socio-political instability.The Zimbabwean HIV-1C epidemic likely originated from multiple introductions in the late 1970s and grew exponentially during the 1980s, corresponding to changing political boundaries and rapid population influx from neighboring countries. The timing and phylogenetic clustering of the Zimbabwean sequences is consistent with an origin in southern Africa and subsequent expansion. HIV-1 sequence data contain important epidemiological information, which can help focus treatment and prevention strategies in light of more recent political volatility in Zimbabwe.

SUBMITTER: Dalai SC

PROVIDER: S-EPMC2923658 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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Evolution and molecular epidemiology of subtype C HIV-1 in Zimbabwe.

Dalai Sudeb C SC de Oliveira Tulio T Harkins Gordon W GW Kassaye Seble G SG Lint Jennifer J Manasa Justen J Johnston Elizabeth E Katzenstein David D

AIDS (London, England) 20091101 18

<h4>Objective</h4>To investigate the origins and evolutionary history of subtype C HIV-1 in Zimbabwe in a context of regional conflict and migration.<h4>Design</h4>HIV-1C pol sequence datasets were generated from four sequential cohorts of antenatal women in Harare, Zimbabwe sampled over 15 years (1991-2006).<h4>Methods</h4>One hundred and seventy-seven HIV-1C pol sequences were obtained from four successive cohorts in Zimbabwe. Maximum-likelihood methods were used to explore phylogenetic relati ...[more]

PMID: 19770693

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Project description:BackgroundPancreas disease (PD) is a viral fish disease which in recent years has significantly affected Norwegian salmonid aquaculture. In Norway, the aetiological agent salmonid alphavirus (SAV) has been found to be represented by the subtype 3 only. SAV subtype 3 has in previous analyses been found to show a lower genetic divergence than the subtypes found to cause PD in Ireland and Scotland. The aim of this study was to evaluate the nucleotide (nt) and amino acid divergence and the phylogenetic relationship of 33 recent SAV subtype 3 sequences. The samples from which the sequences were obtained originated from both PD endemic and non-endemic regions in an attempt to investigate agent origin/spread. Multiple samples throughout the seawater production phase from several salmonid populations were included to investigate genetic variation during an outbreak. The analyses were mainly based on partial sequences from the E2 gene. For some samples, additional partial 6 K and nsP3 gene sequences were available.ResultsThe nucleotide divergence for all gene fragments ranged from total identity (0.0% divergence) to 0.45% (1103 nt fragment of E2), 1.11% (451 nt fragment of E2), 0.94% (6 K) and 0.28% (nsP3). This low nucleotide divergence corresponded well to previous reports on SAV 3 sequences; however the observed divergence for the short E2 fragment was higher than that previously reported. When compared to SAVH20/03 (AY604235), amino acid substitutions were detected in all assessed gene fragments however the in vivo significance of these on for example disease outbreak mortality could not be concluded on. The phylogenetic tree based on the 451 nt E2 fragment showed that the sequences divided into two clusters with low genetic divergence, representing only a single SAV subtype.ConclusionsThe analysed sequences represented two clusters of a single SAV subtype; however some of the observed sequence divergence was higher than that previously reported by other researchers. Larger scale, full length sequence analyses should be instigated to allow further phylogenetic and molecular epidemiology investigations of SAV subtype 3.

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Evolution and molecular epidemiology of subtype C HIV-1 in Zimbabwe.

Publications

Evolution and molecular epidemiology of subtype C HIV-1 in Zimbabwe.

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