Trends in antiretroviral drug resistance and clade distributions among HIV-1--infected blood donors in Sao Paulo, Brazil.
BACKGROUND
We analyzed rates of drug resistance mutations in antiretroviral-naive São Paulo blood donors with recently acquired or established HIV-1 infections and characterized clade diversity in this population.


METHODS
Six hundred forty-eight seropositive blood donor specimens were identified at the Blood Center of São Paulo between July 1998 and March 2002. To discriminate recent infections, samples were subjected to the standardized testing algorithm for recent HIV seroconversion (less-sensitive enzyme immunoassay) testing algorithm. There were 531 samples with a sufficient volume of serum to attempt polymerase chain reaction (PCR) and viral sequencing; 341 (64%) samples yielded a PCR product that could be sequenced for the reverse transcriptase and protease genes. Mutations were analyzed using the 2005 International AIDS Society mutation list.


RESULTS
Of 341 specimens successfully analyzed, 21 (6.3%; 95% confidence interval [CI]: 3.9% to 9.3%) had drug-resistant mutations. The proportion of resistant strains was 12.7% (95% CI: 5.2% to 24.5%) among recently infected individuals compared with 5.0% (95% CI: 2.8% to 8.2%) among those with long-standing infections (P = 0.03). No change in the proportion of drug-resistant strains was observed among recently infected donor samples from the first half of the study period (4 of 32 samples) as compared with the second half (3 of 23 samples; P = 0.95). Of the 341 samples, 277 (81.2%) were classified as subtype B, 25 (7.3%) as subtype F1, 13 (3.8%) as subtype C, and 26 (7.6%) as recombinant strains. The distribution of HIV-1 subtypes was similar among recent and long-standing infected individuals and over time.


CONCLUSIONS
The prevalence of drug-resistant mutations among newly diagnosed persons in São Paulo city is low and similar to what has been described in Europe and the United States. Although HIV-1 subtype B remains predominant, subtypes F and C and recombinant forms are present in substantial proportions in infected donors.
Barreto
Claudia C
CC
Fundaçaõ Pró-Sangue/Hemocentro de Saõ Paulo, Av. Dr. Enéas de Carvalho Aguilar, 15505403-000 Saõ Paulo, Brazil.
Nishyia
Anna
A
Araújo
Luciano V
LV
Ferreira
João E
JE
Busch
Michael P
MP
Sabino
Ester C
EC
D019380:Anti-HIV Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001782:Blood Donors; D001938:Brazil; D024882:Drug Resistance, Viral / Q000235:genetics*; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007124:Immunoenzyme Techniques; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013997:Time Factors
D019380:Anti-HIV Agents; D012367:RNA, Viral; D054303:HIV Reverse Transcriptase; D016333:HIV Protease