Genetic Characterizations and Molecular Evolution of the Measles Virus Genotype B3's Hemagglutinin (H) Gene in the Elimination Era.

Nan Zhou,Yue Huang,Lu Zhou,Bei Wang,Mingma Li

doi:10.3390/v13101970

Abstract

Measles virus (MeV) genotype B3 is one globally significant circulating genotype. Here, we present a systematic description of long-term evolutionary characterizations of the MeV genotype B3’s hemagglutinin (H) gene in the elimination era. Our results show that the B3 H gene can be divided into two main sub-genotypes, and the highest intra-genotypic diversity was observed in 2004. MeV genotype B3’s H gene diverged in 1976; its overall nucleotide substitution rate is estimated to be 5.697 × 10−4 substitutions/site/year, and is slowing down. The amino acid substitution rate of genotype B3’s H gene is also decreasing, and the mean effective population size has been in a downward trend since 2000. Selection pressure analysis only recognized a few sites under positive selection, and the number of positive selection sites is getting smaller. All of these observations may reveal that genotype B3’s H gene is not under strong selection pressure, and is becoming increasingly conservative. MeV H-gene or whole-genome sequencing should be routine, so as to better elucidate the molecular epidemiology of MeV in the future.

Highlights

Measles is a highly contagious illness manifesting as a characteristic erythematous, maculopapular rash caused by the measles virus (MeV) [1]
Phylogenetic relation of MeV genotype B3’s H gene was constructed via a maximum likelihood (ML) method based on the K2P+G4 model by using MEGA version X, with 1000 bootstrap replications for branch support [22]
The phylogenetic tree was constructed based on the ML method, revealing two sub-genotypes, named 3.1 and 3.2 (Supplementary Figure S1)

Summary

Introduction

Measles is a highly contagious illness manifesting as a characteristic erythematous, maculopapular rash caused by the measles virus (MeV) [1]. In the period 2000–2016, the incidence of measles declined from 145 per 1 million population to 18 per 1 million population. In recent years, measles has re-emerged, and its incidence increased to 25, 49, and 120 per 1 million population in the years from 2017 to 2019, respectively [2,3,4]. Measles outbreaks have been observed in some developed regions with high vaccine coverage [5,6,7]. The WHO’s established goal of eradicating measles is challenging, and measles is still a major public health issue for human beings. Delays in pediatric vaccination as a consequence of the COVID-19 pandemic may exacerbate the transmission of measles and other vaccine-preventable diseases [8]

Methods

Results

Conclusion