Metagenomics identification of genetically distinct tick virome in India unveils signs of purifying selection, and APOBEC and ADAR editing

Recently, several tick-borne zoonotic viruses have been identified through the application of virus metagenomics. However, the tick virome in South Asia and the factors driving the evolution of these viruses remain largely unknown. In this study, we report the complete genomes of the genetically distinct Nairobi sheep disease virus (NSDV), Jingmen tick virus (JMTV), Lihan tick virus (LTV), and Mivirus, along with nearly complete genomes of turnip mosaic virus (TMV) and turnip yellows virus (TYV). We also present partial genomes of Tamdy orthonairovirus, Nayun tick nairoviruses (NTNV), PTV-like viruses, Xinjiang tick-associated virus-1 (XTAV1), Totivirus, Kismayo viruses, Quaranjavirus, and Brown dog tick phlebovirus-2 (BDTPV-2), identified from Indian ticks through virus metagenomics. The diversity was categorized into distinct groups specific to particular host organisms and/or geographical regions. Our findings also indicated that selection pressure for codon usage in these viruses was influenced by purifying selection, which induces transition mutations potentially through apolipoprotein B mRNA editing enzyme, catalytic polypeptide (APOBEC) and adenosine deaminases acting on RNA (ADAR) editing.