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.
Ganbold et al. (Wed,) studied this question.