Frequency of the CCR5 delta 32 mutant allele in HIV-1-positive patients, female sex workers, and a normal population in Taiwan

Abstract

A specific 32-nucleotide deletion mutant of the CCR5 gene (Accr5), the coreceptor gene for human immunodeficiency virus type 1 (HIV-1), can effectively suppress the transmission and pathogenesis of the virus. Individuals homozygous for the delta ccr5 allele resist primary macrophage-tropic HIV-1 infection, despite multiple high-risk sexual exposures. This gene deletion is relatively common among Caucasians but uncommon among Africans, Asians, and South Americans. We used polymerase chain reaction (PCR) technology to determine the frequency of the delta ccr5 allele in a Taiwanese population with diverse health status and social backgrounds. Subjects included 24 HIV-1-infected persons in the northern and southern parts of Taiwan; 131 HIV-1 high-risk, licensed female sex workers in the northern part of the island (21% of whom were aborigines); and 187 unrelated, healthy, HIV-1-negative individuals in southern Taiwan. PCR with primers encompassing the entire CCR5 gene was used to explore possible deletions at regions other than the 32-nucleotide area in the female sex workers. No ccr5 deletions were detected, indicating that they are rare or absent in the Taiwanese population. This finding implies that delta ccr5 is not likely to be part of the defense against the spread of HIV-1-infection in Taiwanese.

PIP: Delta CCR5, a specific 32-nucleotide deletion mutant of the CCR5 gene, effectively suppresses HIV-1 transmission and pathogenesis. The presence of this allele may provide a natural defense mechanism against infection by primary macrophage-tropic HIV-1 infection. As of 1996, this mutation had been detected only in Caucasians; however, subsequent studies detected the allele in 2-6% of people from various regions in India and the Middle East. The present study utilized polymerase chain reaction (PCR) technology to investigate the frequency of the delta CCR5 genotype in three groups of Taiwanese of both Chinese and aboriginal ancestry. Enrolled were 24 HIV-1-infected patients from northern and southern Taiwan, a high-risk cohort of 131 female sex workers in northern Taiwan, and 187 healthy HIV-negative subjects from southern Taiwan. Although all subjects were homozygous for the wild-type CCR5 allele, the delta 32 mutation was not present. Additional PCR analysis in the sex worker subgroup of the entire CCR5 gene also failed to identify any deletion mutations larger than 10 nucleotides. A previous report indicated that the delta CCR5 allele is rare or absent in Chinese populations. Since many cases with slow HIV-AIDS disease progression and the clearance of HIV-1 in a perinatally infected infant have been reported in Taiwan, an as yet unidentified genetic factor that suppresses the transmission, pathogenesis, or replication of HIV-1 must exist in Taiwanese populations. Further studies in various ethnic groups are urged to identify the biologic mechanisms that protect selected individuals from HIV-1 transmission, even in the presence of high-risk practices.