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327 The Diversity of HIV-1 in Central Africa: Focusing on Groups O and N
D. L. Robertson*1, S. Souquiere2, A. Ayouba3, O. Pybus1, F. Simon4, and P. Roques2
1Univ. of Oxford, UK; 2CIRMF, Franceville, Gabon; 3Ctr. Pasteur du Cameroon, Yaounde, Cameroon; and 4Ctr. Hosp. Charles Nicolle, Rouen, France
Background: The HIV/AIDS pandemic is the result of the spread of HIV-1 group M viruses from Central Africa to other parts of Africa and the rest of the world. In this work, we present analysis of the other HIV-1 groups, O and N, and address the question of how groups O and N differ from group M in terms of sequence diversity.
Methods: Fifty-five non-group M samples were obtained from HIV-infected individuals residing in France (most had links to Cameroon) and in Cameroon, and sequences derived for the different genomic regions gag, pol, C2-V3, and/or gp41 and/or for near complete genomes. Phylogenetic methods were used to reconstruct the evolutionary history of these sequences, and comparisons were made with sequences available in GenBank.
Results: Only a fraction of the HIV-infected individuals in Cameroon (2(5%) are carriers of group O strains, and group N infections are extremely rare (only 6 cases have so far been identified). The diversity among our 49 group O viruses is comparable to group M, indicating group O has existed in the human population for a similar time scale to group M, whereas group Ns diversity is lower, indicating a more recent emergence. Notably, there is relatively strong phylogenetic substructure amongst group O viruses. However the distinction between these clades is not strong, so, unlike group M, group O subtypes cannot be identified. The group O tree structure seems to simply represent the evolutionary history of these viruses in Cameroon with a few direct epidemiological links to other countries. A similar lack of "subtypeness" has been reported for HIV-1 group M evolutionary history in the Democratic Republic of Congo.
Conclusions: It cannot be ruled out that group O (or even group N) viruses could, in the future, contribute increasingly to the HIV pandemic, and ominously recombinants between groups O and M have already been identified. An understanding of all of the diversity of circulating immunodeficiency viruses, regardless of their current contribution to the HIV/AIDS pandemic, is crucial for the monitoring of epidemic viral forms and the development of a vaccine (or vaccines) capable of controlling HIV-1 world-wide.
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