Unveiling the host arsenal: Interactome profiling of ALV-J p32 integrase reveals novel antiviral targets.

Avian leukosis virus subgroup J (ALV-J) is a highly oncogenic retrovirus that causes immunosuppression and tumors in poultry, posing a significant threat to poultry industry. Integration of the viral genome into the host genome, catalyzed by the viral integrase p32, is a critical and irreversible step in the ALV-J replication cycle. However, the host factors that regulate this process remain poorly understood. Leveraging genomics, targeting viral proteins to capture host proteins is a widely adopted approach for analyzing viral life cycle. In this study, through co-immunoprecipitation (Co-IP) combined with mass spectrometry (MS) sequencing technology, 54 high-confidence host proteins interacting with ALV-J p32 were identified. Systematic bioinformatics analysis of host proteins revealed that most of the captured host proteins were localized in nucleus and participated in essential signaling pathways, such as protein export and RNA synthesis. These findings suggest that host proteins are deeply involved in regulating p32-mediated ALV-J integration. Among these proteins, DNAJC9 was validated as a critical host cofactor through Co-IP, Western blots and laser confocal microscopy. Functional studies revealed that DNAJC9 directly interacts with p32 and enhances ALV-J replication, suggesting a proviral role. Other potential mediators, such as USP16 and HMGN4, exhibit proviral activity but lack direct interaction with p32, warranting further mechanistic investigation. Collectively, our findings uncover a novel host-virus interaction axis involving DNAJC9-p32 that facilitates ALV-J replication. This study provides a mechanistic insight into the host-driven regulation of retroviral integration and offers a potential molecular target for the development of antiviral strategies against ALV-J.