title: Primary drug resistance and transmission analysis of HIV-1 in acute and recent drug-naïve seroconverters in Singapore.
abstract: OBJECTIVE
  The aim of the study was to elucidate primary drug resistance and transmission of HIV-1 in acute and recent drug-naïve seroconverters in Singapore.
  
  
  METHODS
  Acute and recent HIV-1 seroconverters were enrolled in the study. The HIV-1 polymerase (pol) gene was sequenced and used for genotypic drug resistance analysis and phylogenetic analysis. HIV-1 transmission clusters were inferred from phylogenetic clustering analysis.
  
  
  RESULTS
  Of the 60 subjects analysed, 95% were men, and 73.3% were men who have sex with men (MSM). Six HIV-1 subtypes were identified, including CRF01_AE (46.7%), subtypes B (30%), B' (15%) and G (1.7%), CRF33_01B (1.7%) and CRF34_01B (5%). Primary genotypic resistance was detected in only one (1.7%) subtype B variant. Thirty-one patients (51.7%) were phylogenetically clustered, of whom 90% reported having local risk exposure, compared with 59% of the patients who were not phylogenetically clustered [odds ratio (OR) 6.35, 95% confidence interval (CI) 1.65-23.95]. MSM (OR 5.63, 95% CI 1.17-27.15), high viral load (OR 4.28, 95% CI 1.37-13.36) and young age (OR 0.92, 95% CI 0.85-0.99) were independently associated with clustered individuals.
  
  
  CONCLUSIONS
  In Singapore, HIV-1 primary resistance is insignificant; individuals with seroconversion account for about half of onward transmission among recently infected seroconverters. MSM, high viral load and young age are factors that facilitate transmission. Early detection of these individuals is of paramount importance for the prevention of HIV-1 transmission.
authors.affiliation: Department of Infectious Diseases, Tan Tock Seng Hospital, Tan Tock Seng 308433, Singapore.
authors.forename: C C
authors.initials: CC
authors.lastname: Lee
authors.forename: Y J
authors.initials: YJ
authors.lastname: Sun
authors.forename: T
authors.initials: T
authors.lastname: Barkham
authors.forename: Y S
authors.initials: YS
authors.lastname: Leo
mesh_terms: D000328:Adult; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015751:Genes, pol / Q000235:genetics*; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology / Q000635:transmission*; D006679:HIV Seropositivity / Q000188:drug therapy / Q000821:virology; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D012846:Singapore / Q000453:epidemiology; D019562:Viral Load