title: Molecular epidemiology of HIV-1 infection in Taiwan from 2005 to 2008: further spread of CRF07_BC and emergence of CRF07_BC/subtype B dual infection.
abstract: BACKGROUND
  In 2004, HIV-1 infection among Taiwanese injection drug users (IDUs) started to surge. In 2007, a resurgence of HIV-1 epidemic among men having sex with men (MSM) occurred. We conducted a molecular epidemiological study of HIV-1 among different risk groups in Taiwan from 2005 to 2008.
  
  
  METHODS
  In total 1133 HIV-1-infected adults including 576 IDUs, 464 MSM, and 93 heterosexuals were recruited. HIV-1 subtypes were determined using nested multiplex polymerase chain reaction and phylogenetic analysis. Dual infection was confirmed using cloning, sequencing, and heteroduplex mobility assay.
  
  
  RESULTS
  Among HIV-1/AIDS subjects, 96.1% MSM and 62.5% heterosexual males were infected with subtype B, whereas 66.7% female heterosexuals were infected with CRF01_AE. Most IDUs (84.5%) were infected with CRF07_BC. Four heterosexual males, 2 females and 2 MSM who were not IDUs had CRF07_BC. Forty-nine patients had CRF07_BC/subtype B dual infection and 44 (89.8%) were IDUs. Multivariate logistic regression showed that the odds ratio for dual infection among IDUs who shared syringes >5 times per month was 4.7 (95% confidence interval = 1.3 to 17.7). Phylogenetic analyses revealed that there were 2 main groups of CRF07_BC strains with sporadic transmission between different risk groups. Among 10 IDUs infected with CRF01_AE, 7 cases were clustered with an outbreak happened in 2005 and 3 cases were clustered with other strains from heterosexual population.
  
  
  CONCLUSIONS
  In Taiwan, 7.8% of HIV-1-infected IDUs had dual infection. It may have important impact to their clinical management. Although CRF07_BC was still remained in IDUs, it has spread to MSM and heterosexual populations.
authors.affiliation: AIDS Prevention and Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yen-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Lee
authors.forename: Marcelo
authors.initials: M
authors.lastname: Chen
authors.forename: Shao-Yuan
authors.initials: SY
authors.lastname: Chuang
authors.forename: Hsin-Fu
authors.initials: HF
authors.lastname: Liu
authors.forename: Wing-Wai
authors.initials: WW
authors.lastname: Wong
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Lin
authors.forename: Hung-Chin
authors.initials: HC
authors.lastname: Tsai
authors.forename: Jen-Hsien
authors.initials: JH
authors.lastname: Wang
authors.forename: Yi-Ming Arthur
authors.initials: YM
authors.lastname: Chen
mesh_terms: D000328:Adult; D004279:DNA, Viral / Q000032:analysis; D004196:Disease Outbreaks; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D015819:Substance Abuse, Intravenous; D013624:Taiwan / Q000453:epidemiology
chemical_list: D004279:DNA, Viral