Molecular Epidemiology of Varicella-zoster Virus in East London, England, Between 1971 and 1995

The molecular epidemiology of varicella-zoster virus in London, England, between 1971 and 1995 was examined by using two informative polymorphic markers, variable repeat region R5 and a BglI restriction site in gene 54. Viruses from 105 cases of chickenpox and 144 of zoster were typed. Two alleles of R5, A and B, were found at prevalences of 89 and 6%, respectively. No difference in allele frequency between the zoster and chickenpox cases was found, and no change in the frequencies of these alleles was observed to occur over time. By contrast, a BglI restriction site (BglI+) was found with increasing frequency over time among cases of varicella (P < 0.005) and, to a lesser extent, cases of zoster. The BglI+ polymorphism was strongly associated (P < 0.0005) with zoster in subjects who had immigrated to the United Kingdom from countries with low adult immunity to varicella (LAIV). Sixty-three percent of the subjects with zoster who had emigrated from countries with LAIV carried the BglI+ virus, in contrast to 10% of adults who had grown up in countries with high adult immunity to varicella. The significance of these data, in view of the changing epidemiology of chickenpox, is discussed.