title: Prevalence of transmitted HIV-1 antiretroviral resistance among patients initiating antiretroviral therapy in Brazil: a surveillance study using dried blood spots.
abstract: BACKGROUND
  In Brazil, the use of antiretrovirals is widespread: more than 260,000 individuals are currently undergoing treatment. We conducted a survey targeting antiretroviral-naïve individuals who were initiating antiretroviral therapy (ART) according to local guidelines. This survey covered five Brazilian regions.
  
  
  METHODS
  The HIV Threshold Survey methodology (HIV-THS) of the World Health Organization was utilized, and subjects were selected from seven highly populated cities representative of all Brazilian macro-regions. Dried blood spots (DBS) were collected on SS903 collection cards and were transported by regular mail at room temperature to a single central laboratory for genotyping.
  
  
  RESULTS
  We analysed samples from 329 individuals initiating highly active antiretroviral therapy (HAART), 39 (11.8%) of whom were harbouring transmitted drug resistance (TDR). The mean CD4+ T cell count was 253 cells/µL, and the mean viral load was 142,044 copies/mL. The regional prevalence of resistance was 17.0% in the Northeast, 12.8% in the Southeast, 10.6% in the Central region, 8.5% in the North and 8.5% in the South. The inhibitor-specific TDR prevalence was 6.9% for nucleoside reverse transcriptase inhibitors, 4.9% for non-nucleoside reverse transcriptase inhibitors and 3.9% for protease inhibitors; 3.6% of individuals presented resistance to more than one class of inhibitors. Overall, there were trends towards higher prevalences of subtype C towards the South and subtype F towards the North. Of the DBS samples collected, 9.3% failed to provide reliable results.
  
  
  CONCLUSIONS
  We identified variable TDR prevalence, ranging from intermediate to high levels, among individuals in whom HIV disease progressed, thus implying that resistance testing before initiating ART could be effective in Brazil. Our results also indicate that the use of DBS might be especially valuable for providing access to testing in resource-limited and remote settings.
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Celina M P
authors.initials: CM
authors.lastname: de Moraes Soares
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Tania R C
authors.initials: TR
authors.lastname: Vergara
authors.affiliation: Virology Research Laboratory, Federal University of Bahia, Salvador, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Brites
authors.affiliation: Federal District Hospital Foundation, Brasília, Brazil.
authors.forename: Jose D U
authors.initials: JD
authors.lastname: Brito
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Gorki
authors.initials: G
authors.lastname: Grinberg
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil; Molecular Biology Laboratory, Lusíada University, Santos, SP, Brazil.
authors.forename: Marcos M
authors.initials: MM
authors.lastname: Caseiro
authors.affiliation: Municipality of Itajaí, Itajaí, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Correa
authors.affiliation: Municipality of Porto Alegre, Porto Alegre, Brazil.
authors.forename: Theodoro A
authors.initials: TA
authors.lastname: Suffert
authors.affiliation: Infection Disease Division, State University of Amazonas, Manaus, Brazil.
authors.forename: Flavio R
authors.initials: FR
authors.lastname: Pereira
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Michelle
authors.initials: M
authors.lastname: Camargo
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Luiz M
authors.initials: LM
authors.lastname: Janini
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil; Molecular Biology Laboratory, Lusíada University, Santos, SP, Brazil.
authors.forename: Shirley
authors.initials: S
authors.lastname: Komninakis
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Maria C A
authors.initials: MC
authors.lastname: Sucupira
authors.affiliation: Infectious Diseases Unit, Federal University of São Paulo (UNIFESP), São Paulo, Brazil; rsdiaz@catg.com.br.
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Diaz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001769:Blood / Q000821:virology; D001938:Brazil; D004279:DNA, Viral / Q000235:genetics; D003890:Desiccation / Q000379:methods; D024882:Drug Resistance, Viral; D005260:Female; D005838:Genotype; D060005:Genotyping Techniques; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013048:Specimen Handling / Q000379:methods; D055815:Young Adult
chemical_list: D004279:DNA, Viral
keywords: Brazil; HIV subtype; antiretroviral therapy; dried blood spots; genotyping; transmitted drug resistance