Chaperonin CCT5 binding with porcine parvovirus NS1 promotes the interaction of NS1 and COPƐ to facilitate viral replication

Porcine parvovirus (PPV) is an important pathogen causing reproductive disorders in first pregnant sows. The non-structure protein NS1 of PPV is a multifunctional protein playing a key role in viral replication. Chaperonin-containing T-complex polypeptide complex (CCT), containing CCT1-CCT8 subunits, belongs to the type II chaperones that interact with proteins to help in folding and maintaining. In this study, CCT5, for the first time, was found to be one of the host interacting proteins of PPV NS1, and CCT5 was directly bound with NS1. Interference of CCT5 expression by specific siRNA and knockout of CCT5 expression by CRISPR/Cas9 suppressed PPV replication, while overexpression of CCT5 promoted PPV replication in PK-15 cells. The interaction of CCT5 and PPV NS1 was dependent on the 36-42 aa motif at the N-terminal end of NS1. More importantly, CCT5 was also found interacting with COPƐ, which has previously been demonstrated to promote PPV replication by regulating type I interferon. Interference and knockout of CCT5 expression significantly reduced the interaction of PPV NS1 and host protein COPƐ, and promoted the IFN-β expression. These results show that CCT5 mediates the interaction of PPV NS1 and COPƐ to regulate viral replication, providing new insight into the mechanism of PPV replication.