371-M. Decline in the Rate of Genotypic Resistance to Antiretroviral Drugs in Recent HIV Seroconverters in Spain

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Session 56 Poster Session
Acute Infection: Resistance, Fitness, and Transmission
Session Time: 4:30-6:30 pm
Room 4E-F

371-M.

Decline in the Rate of Genotypic Resistance to Antiretroviral Drugs in Recent HIV Seroconverters in Spain
C. de Mendoza¹, J. del Romero², C. Rodríguez², A. Corral¹, and V. Soriano*¹
¹Inst. de Salud Carlos III and ²Ctr. Sandoval, Madrid, Spain

Background: Resistance to antiretroviral drugs represents one of the major obstacles for the success of HIV therapy. Viruses carrying drug-resistant mutations can be transmitted and, then, compromise the response to therapy in drug-naďve individuals.
Methods: We have compared the rate of primary mutations associated to drug resistance in a well-characterized panel of plasma samples collected from individuals with primary acute HIV infection or seroconversion lasting <12 months who were attended over the last 5 years in several clinics in Madrid. An automatic sequencer (ABI 3100) was used to generate RT and protease sequences. Sequences were aligned, and HIV subtyping was carried out based on this information.
Results: A total of 52 individuals was examined. Subjects had been exposed to HIV through homosexual (72%), heterosexual (20%), needle sharing (6%), or transfusion (1 subject), without significant differences comparing the 2 periods. Likewise, demographics did not differ in the two groups. The overall prevalence of genotypes associated with reduced drug susceptibility was 25.8% (8/31) in samples collected since 1997 to 1999. In contrast, this rate declined to 4.8% (1/21) in samples collected in 2000 and 2001 (p<0.05). The distribution of resistance genotypes was as follows in the period 1997 to 1999: RT (M41L in 4 subjects; T215Y in 3; M184V in 1; Y181C in 1) and PRO (M46L in 1; V82I in 1; L90M in 1). In contrast, only 1 subject harbouring M46L at the protease was recognized in the period 2000-2001. No differences in the rate of genotypic resistance were found comparing subjects with acute HIV infection and those with recent seroconversion. All virus sequences were characterized as belonging to HIV-1 subtype B.
Conclusions: The rate of genotypic resistance in newly infected individuals has declined significantly in the last 2 years in Madrid. This finding supports that most new infections come from subjects being not exposed to antiretroviral drugs (even not aware of their HIV status) rather than from subjects failing their current antiretroviral treatment. Drug resistance testing in recent seroconverters does not seem to be required before beginning antiretroviral therapy. However, it should be considered when the source of the infection is known to be a subject failing any antiretroviral therapy.

Š2002 9^th Conference on Retroviruses and Opportunistic Infections