Alignment of varicella-zoster virus sequences between Oka vaccine strain and wild-type strain

Abstract

Objective To observe the stability of varicella-zoster virus(VZV) Oka vaccine(V-Oka)strain during subculture,and align VZV sequences between V-Oka strain and wild-type strain from chickenpox patients.Methods V-Oka strain was subcultured to the 50th passage on human diploid cell MRC-5.VZV DNAs were extracted from the 32nd,34th,38th,42nd,46th and 50th passages of V-Oka strains and wild-type strains.The major genes( ORF31,ORF62,ORF68 and repeat regions)of V-Oka strains and wild-type strains were amplified by PCR and sequenced.DNA sequences between V-Oka strains and wild-type strains were aligned.Results In comparison with DNA sequences of V-Oka strain in GenBank,ORF31,ORF62,0RF68,repeat regions sequences of V-Oka strains from the 32nd passage to the 50th passage were stable and seemed to be more attenuated.Unique mutations as same as those in V-Oka stains were not observed in wild-type strains.Conclusions The molecular genetic characteristics of V-Oka strains are stable till the 50th passage.The results of sequence alignment show that pathogenic strains in chickenpox patients are wild-type strains,but not V-Oka strains. Key words: Chickenpox vaccine; Herpesvirus 3, human; Sequence alignment