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J Infect Dis. 2004 Apr 1;189(7):1232-8. Epub 2004 Mar 12.

Synonymous genetic polymorphisms within Brazilian human immunodeficiency virus Type 1 subtypes may influence mutational routes to drug resistance.

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Unidade de Genetica e Biologia Molecular, Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Brazil.



Most published data on antiretroviral-drug resistance is generated from in vitro or in vivo studies of subtype B virus. However, this subtype is associated with <10% of HIV infections worldwide, and it is essential to explore subtype-specific determinants of drug resistance. One potential cause of the differences between subtypes is the synonymous codon usage at key resistance positions.


We investigated the nucleotide sequences at drug resistance-related sites, for all major Brazilian subtypes (B, C, and F1) of human immunodeficiency virus type 1 (HIV-1) group M.


We identified a change at positions 151 and 210 of the reverse-transcriptase region in subtype F1, such that the emergence of these key nucleoside/nucleotide analogue resistance mutations required an extra nucleotide change in subtype F1, compared with subtypes B and C. The clinical significance of position 210 was confirmed within a large Brazilian database, in which we identified a lower prevalence of the L210W mutation in subtype F1 virus, compared with subtype B virus, in patients matched for thymidine-analogue experience. An inverse relationship between the L210W and K70R mutations was also observed.


The findings of the present study illustrate an important mechanism by which a subtype may determine genetic routes to resistance, with implications for treatment strategies for populations infected with HIV-1 subtype F.

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