Absence of the Kilifi Mutation in the Rhinovirus-Binding Domain of ICAM-1 in a Caucasian Population

Abstract

Human rhinoviruses (HRV), responsible for approximately 60% of the common colds, are divided into two groups, according to their receptor specificity. The major group of HRVs gains access to human cells by binding to the intercellular adhesion molecule-1 (ICAM-1), whereas HRVs of the minor group use members of the low-density lipoprotein receptor (LDLR) family for cell entry. Previous studies confirmed that the HRV-binding region of ICAM-1 is located in the amino-terminal immunoglobulin-like (Ig) domain 1, which is encoded by exon 2 of the ICAM-1 gene. An A → T transversion in codon 29 of ICAM-1 exon 2 causes a lysine to methionine substitution (K29M), and was found at a high frequency (33.2%) in Kilifi (Kenya), as well as in other African populations. In this study we examined whether polymorphisms in exon 2 of ICAM-1 could be detected in a Caucasian population, assuming that these could be of importance in HRV binding. DNA from 100 healthy, unrelated, Belgian volunteers was obtained through a noninvasive swish-and-spit method. Using a primer set in the adjacent intron sequences, the full-length ICAM-1 exon 2 was amplified by polymerase chain reaction (PCR), followed by direct sequencing of the PCR product. No polymorphisms could be demonstrated in exon 2 of the ICAM-1 gene among all 100 tested individuals. The rhinovirus-binding Ig domain 1 of ICAM-1 seems to be a highly conserved region in the Caucasian population.