BV/ODV-E26 is a conserved baculoviral inhibitory factor for optimizing viral virulence in lepidopteran hosts

Alphabaculoviruses induce abnormal behavior in lepidopteran larval hosts. A baculoviral gene, <i>bv/odv-e26</i>, is crucial for behavioral manipulation in <i>Bombyx mori</i> larvae by Bombyx mori nucleopolyhedrovirus (BmNPV). However, how <i>bv/odv-e26</i> fulfills its role in this phenotype remains largely unknown. In this study, we found that the overexpression of BmNPV <i>bv/odv-e26</i> delayed viral infection in cultured cells and decreased pathogenicity in <i>B. mori</i> larvae. We also discovered that homologs of <i>bv/odv-e26</i> are conserved more widely in alphabaculoviruses than previously thought. The inhibitory activity was demonstrated in <i>bv/odv-e26</i> homologs of phylogenetically close and distant baculoviruses, indicating conserved inhibitory function among alphabaculoviruses. Furthermore, locomotory analyses revealed that <i>bv/odv-e26</i> increased larval locomotory activity but had little effect on the timing of abnormal behavior initiation. Collectively, our findings demonstrate that <i>bv/odv-e26</i> is a baculoviral inhibitory factor that is widely conserved in the genus <i>alphabaculovirus</i> and may reduce viral virulence for successful host behavioral manipulation.