title: CCR5 haplotypes and mother-to-child HIV transmission in Malawi.
abstract: BACKGROUND
  CCR5 and CCR2 gene polymorphisms (SNPs) have been associated with protection against HIV transmission in adults and with delayed progression to AIDS. The CCR5 Delta32 deletion and SNP -2459G are associated with reduced expression of the CCR5 protein.
  
  
  RESULTS
  We investigated the association between infant CCR2/CCR5 diplotype and HIV mother to child transmission (MTCT) in Malawi. Blood samples from infants (n = 552) of HIV positive women who received nevirapine were genotyped using a post-PCR multiplex ligase detection reaction and haplotypes were identified based on 8 CCR2/CCR5 SNPs and the open reading frame 32 base pair deletion. Following verification of Hardy-Weinberg equilibrium, log linear regression was performed to examine the association between mutations and MTCT. Overall, protection against MTCT was weakly associated with two CCR5 SNPs, -2459G (Risk ratio [RR], 0.78; confidence interval [CI], 0.54-1.12), and the linked CCR5 -2135T (RR, 0.78; CI, 0.54-1.13). No child carried the CCR5 Delta32 SNP. Maternal Viral Load (MVL) was found to be an effect measure modifier. Among mothers with low MVL, statistically significant protection against MTCT was observed for -2459G (RR, 0.50; CI, 0.27-0.91), and -2135T (RR, 0.51; CI, 0.28-0.92). Statistically significant protection was not found at high MVL.
  
  
  CONCLUSIONS
  Results from this study suggest that CCR5 SNPs -2459G and -2135T associated with reduced receptor expression protect against MTCT of HIV at low MVLs, whereas high MVLs may over-ride differences in coreceptor availability.
authors.affiliation: University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Bonnie R
authors.initials: BR
authors.lastname: Pedersen
authors.forename: Deborah
authors.initials: D
authors.lastname: Kamwendo
authors.forename: Melinda
authors.initials: M
authors.lastname: Blood
authors.forename: Victor
authors.initials: V
authors.lastname: Mwapasa
authors.forename: Malcolm
authors.initials: M
authors.lastname: Molyneux
authors.forename: Kari
authors.initials: K
authors.lastname: North
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rogerson
authors.forename: Peter
authors.initials: P
authors.lastname: Zimmerman
authors.forename: Steven R
authors.initials: SR
authors.lastname: Meshnick
mesh_terms: D005260:Female; D015658:HIV Infections / Q000150:complications / Q000635:transmission*; D006239:Haplotypes; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008295:Malawi / Q000453:epidemiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious; D019713:Receptors, CCR5 / Q000235:genetics*