Interaction Network Characterization of Infectious Bronchitis Virus Nsp2 with Host Proteins.

Infectious bronchitis (IB) is a highly contagious acute viral disease that leads to substantial economic losses in the poultry industry. Previous research conducted in our laboratory has indicated that Nsp2 may serve as a key virulence factor within the IBV genome, as evidenced by its pronounced divergence between the field strain and its attenuated counterpart. Understanding the interaction between Nsp2 and host proteins is crucial to elucidating the role of the Nsp2 protein in the pathogenesis and proliferation of IBV. Currently, much remains to be uncovered regarding the host proteins that interact with the IBV Nsp2 protein. In this study, 10 host proteins, including COX1, COX3, NFIA, ITGA1, ATP1B1, ATP1B3, ABCB1, ISCA1, DNAJA1, and IREB2, were screened to interact with IBV Nsp2 through yeast two-hybrid experiments and molecular docking simulations. Furthermore, the interaction of Nsp2 with ATP1B3, DNAJA1, and ISCA1 proteins was further validated through co-immunoprecipitation and confocal experiments. The GO, KEGG, and PPI databases revealed that the host proteins interacting with Nsp2 are primarily associated with ATPase activation, Fe-S cluster binding, ion homeostasis, and innate immune regulation. The examination of the expression levels of these Nsp2-interacting host proteins during IBV infection demonstrated the significant downregulation of COX3, COX1, ATP1B1, and ATP1B3, while NFIA, DNAJA1, and IREB2 showed significant upregulation. Moreover, our study identified that IBV enhances viral replication by upregulating DNAJA1 expression, although the underlying mechanism requires further investigation. These findings provide valuable insights into the potential role of the Nsp2 protein in the pathogenesis of IBV.