ABSTRACT
Chikungunya virus (CHIKV) is considered a public health problem due to its rapid spread and high morbidity. In 2016-2017 an outbreak of CHIKV was occurred in Pakistan but the data regarding the genomic diversity of CHIKV was not reported. Hence, the current study aimed to determine the genetic diversity of CHIKVs in Pakistan. A cross sectional study was carried out using sera of infected CHIKV patients (n = 1549) during the outbreak in Pakistan (2016-2018). Nucleotide sequencing of non-structural genes of CHIKV from eight isolates were performed followed by phylogenetic analysis using Bayesian method. Phylogenetic analysis suggested that the Pakistani CHIKV strains belonged to Indian Ocean Lineage (IOL) of genotype ECSA and C1.3a clade. Furthermore, the Pakistani isolates showed several key mutations (nsP2-H130Y, nsP2-E145D, nsP4-S55N and nsP4- R85G) corresponding to mutations reported in 2016 Indian strains of CHIKV. The molecular analysis revealed high evolutionary potential of CHIKV strains as well as better understanding of enhanced virulence and pathogenesis of this outbreak. The study highlights the need to continue surveillance in order to understand viral diversity over time and to devise preventive measures to limit diseases transmission in the region.
Subject(s)
Chikungunya Fever/epidemiology , Chikungunya Fever/virology , Chikungunya virus/isolation & purification , Viral Nonstructural Proteins/genetics , Amino Acid Substitution , Chikungunya virus/classification , Chikungunya virus/genetics , Cross-Sectional Studies , Genome, Viral , Genotype , Humans , Pakistan/epidemiology , PhylogenyABSTRACT
The chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus, which has infected millions of people in Africa, Asia, Americas, and Europe since it remerged in India and Indian Ocean regions in 2005-2006. The purpose of this study was to evaluate the genetic diversity and evolutionary changes in CHIKV from 2016 to 2018 in Pakistan. Blood specimens were collected and processed following the Centers for Disease Control and Prevention Trioplex Protocol. Sequencing and phylogenetic analysis of complete coding sequence of representative isolates from the CHIKV outbreak was carried out during December 2016 to July 2018, a total of 1549 samples were received, out of which 50% (n = 774) were found positive for CHIKV RNA. Mean age of chikungunya positive patients was 31.8 ± 15.7 years and most affected were between 21 and 40 years of age. The Pakistan CHIKV strains clustered with the Indian Ocean sublineage of East/Central/South African with cocirculation of some variants In the structural proteins region, two noteworthy changes (A226V and D284E) were observed in the membrane fusion glycoprotein E1. Key substitutions in the neutralizing epitopes site and a few changes indicative of adaptive to other insect cells were also detected in Pakistani strains. This study provides the emerging trend of CHIKV in the country for early identification of potential variants of high virulence and preventive measures for vector borne disease especially in the endemic areas.
