Characterization of a novel Iflavirus from the locust Calliptamus italicus in Xinjiang, China.

Insect-specific viruses represent a promising yet underexplored resource for the biological control of locust pests. In this study, we performed metatranscriptomic sequencing of three dominant locust species-Calliptamus italicus, Calliptamus barbarus, and Oedaleus decorus decorus-collected from field populations in Xinjiang, China. Bioinformatic analysis identified 32 RNA viruses, 137 DNA viruses, and 33 unclassified viruses. Notably, this study reports the first detection of a novel insect-specific virus in locusts. Phylogenetic and homology analyses revealed that the newly discovered virus belongs to the family Iflaviridae (order Picornavirales), and we provisionally name it Xinjiang Calliptamus italicus Iflavirus (XCiIV). Using transcriptome sequencing and rapid amplification of cDNA ends (RACE), we obtained the complete genome sequence, totaling 9,996 base pairs. The XCiIV genome contains a single predicted open reading frame (ORF) encoding a polyprotein of 2,891 amino acids, which is proteolytically processed into four functional proteins: capsid proteins, RNA helicase, 3C protease, and RNA-dependent RNA polymerase (RdRp). To our knowledge, this is the first report of an Iflavirus identified in C. italicus from the Xinjiang region. The complete genome sequence and comparative analysis of XCiIV expand the known diversity of insect Iflaviruses and provide a reference for future studies on the molecular evolution and host adaptation of locust-associated viruses.