title: Frequency of subtype B and F1 dual infection in HIV-1 positive, Brazilian men who have sex with men.
abstract: BACKGROUND
  Because various HIV vaccination studies are in progress, it is important to understand how often inter- and intra-subtype co/superinfection occurs in different HIV-infected high-risk groups. This knowledge would aid in the development of future prevention programs. In this cross-sectional study, we report the frequency of subtype B and F1 co-infection in a clinical group of 41 recently HIV-1 infected men who have sex with men (MSM) in São Paulo, Brazil.
  
  
  METHODS
  Proviral HIV-1 DNA was isolated from subject's peripheral blood polymorphonuclear leukocytes that were obtained at the time of enrollment. Each subject was known to be infected with a subtype B virus as determined in a previous study. A small fragment of the integrase gene (nucleotide 4255-4478 of HXB2) was amplified by nested polymerase chain reaction (PCR) using subclade F1 specific primers. The PCR results were further confirmed by phylogenetic analysis. Viral load (VL) data were extrapolated from the medical records of each patient.
  
  
  RESULTS
  For the 41 samples from MSM who were recently infected with subtype B virus, it was possible to detect subclade F1 proviral DNA in five patients, which represents a co-infection rate of 12.2%. In subjects with dual infection, the median VL was 5.3 × 10(4) copies/ML, whereas in MSM that were infected with only subtype B virus the median VL was 3.8 × 10(4) copies/ML (p > 0.8).
  
  
  CONCLUSIONS
  This study indicated that subtype B and F1 co-infection occurs frequently within the HIV-positive MSM population as suggested by large number of BF1 recombinant viruses reported in Brazil. This finding will help us track the epidemic and provide support for the development of immunization strategies against the HIV.
authors.affiliation: Department of Translational Medicine, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Soares de Oliveira
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Pessôa de Farias
authors.forename: Antonio Charlys
authors.initials: AC
authors.lastname: da Costa
authors.forename: Mariana Melillo
authors.initials: MM
authors.lastname: Sauer
authors.forename: Katia Cristina
authors.initials: KC
authors.lastname: Bassichetto
authors.forename: Solange Maria Santos
authors.initials: SM
authors.lastname: Oliveira
authors.forename: Priscilla Ramos
authors.initials: PR
authors.lastname: Costa
authors.forename: Claudia
authors.initials: C
authors.lastname: Tomiyama
authors.forename: Helena Tomoko Iwashita
authors.initials: HT
authors.lastname: Tomiyama
authors.forename: Ester Cerdeira
authors.initials: EC
authors.lastname: Sabino
authors.forename: Esper Georges
authors.initials: EG
authors.lastname: Kallas
authors.forename: Sabri Saeed
authors.initials: SS
authors.lastname: Sanabani
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D060085:Coinfection / Q000453:epidemiology* / Q000821:virology*; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D018451:Homosexuality, Male; D006801:Humans; D007962:Leukocytes / Q000821:virology; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D015995:Prevalence; D011533:Proviruses / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D004279:DNA, Viral