The relevance of KIR diversity in conferring susceptibility/resistance to viral infections in humans has previously not been investigated. Therefore to ascertain whether KIR diversity can influence susceptibility to cytomegalovirus infection we have applied our KIR PCR–SSOP typing to a cohort of blood donors (n = 164) segregated on the basis of their IgG seroconversion status for CMV, 82 individuals were CMV IgG positive while 82 were IgG negative. While a comparison of the 15 KIR gene frequencies between the two groups were broadly similar we did observe a significant increase in KIR phenotypes devoid of 2DL3 in IgG negative group compared to the seropositive group (14.6% versus 2.4%, uncorrected P of 0.004). Our data suggests a specific KIR haplotype may well confer resistance to CMV infection, drawing direct parallels with that observed in the mouse (Lee et al Nature Genetics 2001 28: 42–45).

Further analysis of KIR diversity at the allele level is currently underway. Application of a 2DL4 PCR–SSOP allele identification method to the two CMV groups revealed similar allele/genotype frequencies, ruling out any association with the alleles of this gene.