Genetic Diversity among Varicella-Zoster Virus Vaccine Strains

Abstract

Varicella-zoster virus (VZV) is a causative agent for chickenpox in primary infection and shingles after reactivation from latency. Both varicella and zoster can be prevented by live attenuated vaccines, but the molecular mechanism of attenuation is not clearly understood. In this study, the genome sequences of three varicella vaccine strains were analyzed for the genetic diversity including single nucleotide polymorphism (SNP) and genetic polymorphism. A total of 38 SNPs were identified including 29 substitutions and 9 insertion/deletions. The number of genetically polymorphic sites (GPS) was highest in Varivax and lowest in Varilrix. GPS in the R region including R1, R2, and R3 appeared to be responsible for the genetic polymorphisms in the open reading frame (ORF) 11, 14, and 22 in all three vaccine strains. A relatively large number of GPS were observed in ORF31, 55, and 62, which are known to be essential for virus replication, suggesting that the attenuation of the vaccine strains may be attributed by the diversity of these genes.

Designing a polyvalent vaccine targeting multiple strains of varicella zoster virus using integrated bioinformatics approaches

“…TLR3 recognizes viral doublestranded RNA, which is produced during VZV replication, and activates antiviral immune responses (Hanon and Stephenne, 2011). TLR9 recognizes unmethylated CpG motifs in viral DNA, such as VZV DNA, and induces an immune response (Wang et al, 2005;Yu et al, 2011;Kang et al, 2020;Zheng et al, 2020). By targeting these TLRs, VZV vaccines can stimulate both innate and adaptive immune responses, leading to improved protection against VZV infection.…”

“…Declining cell-mediated immunity (CMI) in aging or immunocompromised individuals can trigger latent VZV reactivation as herpes zoster (Gabutti et al, 2019). The genetic diversity of VZV strains in varicella vaccines suggests that attenuation may result from diverse genes, but the precise mechanism remains unclear (Kang et al, 2020). Recombinant Zoster Vaccine (RZV) and Zoster Vaccine Live (ZVL) are accessible options for preventing herpes zoster.…”