Genomic characterization of a baculovirus isolate, Malacosoma neustria nucleopolyhedrovirus Eriogaster neogena isolate (ManeNPV-Er) from Mongolia

BACKGROUND: Baculoviruses are highly diverse insect-specific DNA viruses that have coevolved with their lepidopteran hosts, often exhibiting high host specificity and geographic population structures. To investigate the genomic basis of host - associated divergence, we sequenced and analyzed the complete genome of a baculovirus isolated from symptomatic Eriogaster neogena larvae collected in Mongolia. METHODS: The complete genome of this isolate, designated Malacosoma neustria nucleopolyhedrovirus Eriogaster neogena isolate (ManeNPV-Er), was sequenced and comparatively analyzed. Phylogenetic and pairwise K2P distance analyses based on lef8/lef9/polh were performed to evaluate its taxonomic relationship with other baculoviruses. RESULTS: Comparative genomic analysis revealed an overall nucleotide identity of 86.9% with Malacosoma neustria nucleopolyhedrovirus (ManeNPV-T2), which was isolated from a different host species (Malacosoma neustria) in Turkey. Despite their close taxonomic relationship, this low identity indicates substantial genomic divergence. Phylogenetic and pairwise K2P distance analyses based on lef8/lef9/polh confirmed their conspecific status. However, the corrected K2P distance suggests incipient divergence, which may require additional genomic and biological evidence to confirm. The significant genetic differentiation of ManeNPV-Er is potentially driven by the combined effects of adaptation to a distinct host and geographic isolation in a different region. Such divergence patterns are consistent with the parallel diversification commonly observed between baculoviruses and their lepidopteran hosts. CONCLUSIONS: Collectively, our findings expand the current understanding of baculovirus genomic diversity and provide new insights into how the interplay of host shift and geographic separation influences viral speciation.