Varicella-zoster virus (VZV) is a causative agent for chickenpox and zoster. Live attenuated vaccines have been developed based on Oka and MAV/06 strains. In order to understand the molecular mechanisms of attenuation, complete genome sequences of vaccine and wild-type strains were compared and single nucleotide polymorphism (SNP) was analyzed. ORF22 and ORF62 contained the highest number of SNPs. The detailed analysis of the SNPs suggested 24 potential vaccine-specific sites. All the mutational events found in vaccine-specific sites were transitional, and most of them were substitution of AT to GC pair. Interestingly, 18 of the vaccine-specific sites of the vaccine strains appeared to be genetically heterogeneous. The probability of a single genome of vaccine strain to contain all 24 vaccine-type sequences was calculated to be less than 4%. The average codon adaptation index (CAI) value of the vaccine strains was significantly lower than the CAI value of the clinical strains.
Bibliographical noteFunding Information:
This work was supported by a research fund from Mogam Biotechnology Research Institute and in part by a grant from Chungbuk National University in 2015.
© 2016 Elsevier Inc.
- Genetic heterogeneity
- Live attenuated vaccine
- Sequence diversity
- Single nucleotide polymorphism (SNP)
- Vaccine-specific sites
- Varicella-zoster virus (VZV)
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