ANALYSIS OF UNITED-KINGDOM WILD-TYPE STRAINS OF VARICELLA-ZOSTER VIRUS - DIFFERENTIATION FROM THE OKA VACCINE STRAIN

In Japan and the United States, where vaccination against varicella-zo ster virus (VZV) infection with the live attenuated Oka strain of vari cella is routine, cases of chickenpox or shingles occurring in vaccine es can be caused by either wildtype or vaccine virus. Differentiating such cases is important epidemiologically and can be achieved only usi ng molecular typing methods. In the United Kingdom, the Oka vaccine is being considered for use in groups at risk of severe primary varicell a, such as seronegative immunocompromised patients and women who may b e considering pregnancy. In addition, seronegative health workers who may be occupationally exposed to VZV infection might also be offered v accination. We analysed 249 U.K, wild-type VZV strains, 105 from cases of chickenpox and 144 from shingles cases, to determine whether they could be distinguished from Oka by the genotyping systems used in Japa n and the United States. Four polymorphic loci were examined, a Pst I restriction site in gene 38, a Bgl 1 restriction site in gene 54, the R5 repeat region, and the R2 repeat region. The results suggest that U .K, strains of VZV are more similar to U.S. strains than to Japanese s trains. All the U.K. wild-type viruses were positive for the Pst 1-1 r estriction site, unlike Oka, which is negative. However, one of thirty strains was indistinguishable from Oka at all other loci. (C) 1997 Wi ley-Liss, Inc.