16th International AIDS Conference Toronto, Canada - August 13 - 18, 2006

MOLECULAR EVIDENCE OF A NEW CIRCULATING RECOMBINANT FORM (CRF) COMPRISING HUMAN IMMUNODEFICIENCY VIRUS TYPE 1 SUBTYPES C AND B IN SOUTHERN BRAZIL

Int Conf AIDS. 2006 Aug 13-18;16 Abstract No. TuAa0205

A.F.A. Santos¹, T.M. Souza¹, E.A.J.M. Soares¹, R.B. Lengruber¹, A.M.B. Martinez², E. Sprinz³, J. Silveira⁴, A. Tanuri¹, M.A. Soares^1
1 Universidade Federal do Rio de Janeiro, Genetica, Rio de Janeiro, Brazil, ² Fundacao Universidade do Rio Grande, Patologia, Rio Grande, Brazil, ³ Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil, ⁴ Fundacao Universidade do Rio Grande, Rio Grande, Brazil

BACKGROUND: The subtypes B and C of HIV-1 co-exist in high prevalence in the southern region of Brazil, providing a milieu to the emergence of mosaic forms or even a circulating recombinant form (CRF). In this study, we wanted to characterize potential B/C mosaics in that region.

METHODS: Viral RNA samples isolated from plasma of 152 patients were sequenced in the PR and RT genomic regions and subtyped through phylogenetic analysis. Five representative isolates with the same pattern structure was selected for determining near full-length nucleotides sequences. Bootscanning analyses and sub-region tree analyses were performed to confirm the CRF breakpoints.

RESULTS: The phylogenetic analysis of pol region from 62 viruses initially assigned as subtype C isolated from patients followed at two Hospitals in the state of Rio Grande do Sul (RS), Brazil, showed that 15 viruses (24.2%) clustered in a separate clade between Brazilian subtypes B and C with a high bootstrap value. Further bootscanning analysis evidenced that all candidates had the same recombinant structure, with a 240 bp fragment of subtype B in the 3’ half of the reverse transcriptase region. Subtype B assignment of this fragment was further confirmed by separate phylogenetic analysis using different methods of tree inference and two distinct cluster robustness tests (bootstrap and internal branch test).

CONCLUSIONS: These mosaics were shown to have a common ancestry and we propose this recombinant form to be termed CRF20_CB. As it represents 11% of the HIV-1 viruses circulating in the southern region of the country, which borders several South American countries, the understanding of its generation and spread is of pivotal importance to the HIV/AIDS epidemic in Brazil and in Latin America.

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2006-08-13
TuAa0205

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