Discovery of a new Getah virus in Culex mosquitoes in Malaysia. Malaysia Getah Virus

We isolated a new Malaysian GETV strain, B254, from mosquitoes Culex fuscocephalus captured at forested area of Mount Ophir in Southern Malaysia in 2012. Phylogenetic analyses revealed that the GETV B254 strain is phylogenetically distinct from the old Malaysian GETV MM2021 but closely related to the China GETV YN12031 of GIV lineage. Despite the low number of strains isolated, the GIV GETV showed higher molecular evolutionary rates and accumulated more amino acid substitutions than the epidemic GIII strains. Selection pressure analyses collectively revealed four positively selected sites in the GETV non-structural genes suggesting possible viral adaptation towards highly efficient replicating virus. While the amino acid substitutions in GIII could confer virulence and epidemic potential of the GETV, the impact of amino acid substitutions in GIV is unclear. It is likely that the GIV strains have been circulating in a distinct transmission cycle involving mainly the mosquitoes and asymptomatic hosts.