title: Homozygous and heterozygous CCR5-Delta32 genotypes are associated with resistance to HIV infection.
abstract: OBJECTIVE
  To investigate evidence for resistance to HIV-1 infection associated with the heterozygous genotype CCR5-+/Delta32 and with the homozygous genotype CCR5-Delta32/Delta32, which results in a nonfunctional CCR5 receptor.
  
  
  METHODS
  Cohort study of initially HIV-seronegative high-risk individuals from eight different cities. Enrollment data were analyzed to investigate the association of demographic factors and risk behaviors with CCR5 genotypes on the assumption that increased genotype prevalence among persons with histories of longer or more intensive exposure to HIV would indicate HIV resistance associated with that genotype. Longitudinal data were analyzed to investigate the association of HIV seroincidence with CCR5 genotypes. The cohort of 2996 individuals included 1892 men who have sex with men (MSM), 474 male injection drug users (IDUs), 347 women at heterosexual risk, and 283 female IDUs.
  
  
  METHODS
  CCR5 genotype, HIV serostatus, demographic factors, and risk behaviors during the 6 months before enrollment, followed by measurement of HIV seroincidence during the subsequent 18 months (for men) and 24 months (for women).
  
  
  RESULTS
  Forty (1.3%) subjects were homozygous CCR5-Delta32/Delta32 and 387 (12.9%) were heterozygous CCR5-+/Delta32. All but 1 CCR5-Delta32/Delta32 individuals and 51 CCR5-+/Delta32 individuals were Caucasian. Among 1531 Caucasian MSM, CCR5-+/Delta32 individuals were present more frequently (22.3%) among those reporting unprotected receptive anal intercourse than among those not reporting this risk (15.9%) (p =.002), suggesting a selective advantage of the heterozygous genotype. CCR5-+/Delta32 individuals also had a significantly reduced relative risk of HIV seroconversion adjusted for unprotected receptive anal intercourse compared with CCR5-/+ individuals (relative risk = 0.30, 95% confidence interval [CI]: 0.08-0.97). CCR5-Delta32/Delta32 prevalence among Caucasian MSM was significantly associated with age among subjects recruited from high HIV seroprevalence cities (New York City and San Francisco) (odds ratio [OR] for each decade increase in age = 2.57, CI: 1.56-4.21) but not among those recruited from lower HIV prevalence sites (Boston, Chicago, Philadelphia, Seattle, and Providence/Pawtucket, Rhode Island) (OR = 1.20, CI: 0.75-1.89).
  
  
  CONCLUSIONS
  Cross-sectional and longitudinal analyses indicated that among high-risk HIV seronegative MSM, CCR5-+/Delta32 and CCR5-Delta32/Delta32 are associated with protection against HIV infection. These findings imply that strategies aimed at reducing susceptibility to HIV infection by blocking CCR5 receptor sites need not seek blockage of all receptor sites to achieve an imperfect but substantial degree of protection.
authors.affiliation: Department of Environmental Medicine, New York University School of Medicine, 650 First Avenue, New York, NY 10016-3240, USA. michael.marmor@med.nyu.edu
authors.forename: M
authors.initials: M
authors.lastname: Marmor
authors.forename: H W
authors.initials: HW
authors.lastname: Sheppard
authors.forename: D
authors.initials: D
authors.lastname: Donnell
authors.forename: S
authors.initials: S
authors.lastname: Bozeman
authors.forename: C
authors.initials: C
authors.lastname: Celum
authors.forename: S
authors.initials: S
authors.lastname: Buchbinder
authors.forename: B
authors.initials: B
authors.lastname: Koblin
authors.forename: G R
authors.initials: GR
authors.lastname: Seage
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology / Q000235:genetics*; D015497:HIV-1 / Q000145:classification / Q000472:pathogenicity; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007113:Immunity, Innate; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019713:Receptors, CCR5 / Q000235:genetics*; D012309:Risk-Taking; D012725:Sexual Behavior; D015819:Substance Abuse, Intravenous / Q000150:complications; D044465:White People
chemical_list: D019713:Receptors, CCR5