Swine TRIM25 inhibits vesicular stomatitis virus replication by activation of type I IFN signaling pathway and binding vRNA.

IMPORTANCE

Vesicular stomatitis virus is a zoonotic rhabdovirus that infects livestock and can cause economically important disease. Tripartite motif-containing 25 (TRIM25) is an E3 ubiquitin ligase involved in innate antiviral signaling, but its role in pigs during vesicular stomatitis virus infection is unclear.

OBJECTIVE

To define the mechanism by which swine TRIM25 restricts vesicular stomatitis virus replication.

METHODS

Porcine 3D4/21 cells with TRIM25 overexpression or knockdown were infected with vesicular stomatitis virus. Viral replication was quantified by immunoblotting, quantitative reverse transcription polymerase chain reaction, and 50% tissue culture infectious dose assays. Type I interferon signaling was assessed by transcript quantification, interferon-beta and interferon-stimulated response element reporter assays, and co-immunoprecipitation. Viral RNA binding was tested by RNA immunoprecipitation.

RESULTS

TRIM25 overexpression reduced viral RNA and infectious titers, whereas TRIM25 knockdown increased replication (p < 0.01). TRIM25 increased interferon-beta and interferon-stimulated gene expression and enhanced interferon-beta and interferon-stimulated response element promoter activity (p < 0.01). Mechanistically, TRIM25 promoted Lys63-linked ubiquitination of RIG-I and increased phosphorylation of TANK-binding kinase 1 and interferon regulatory factor 3. TRIM25 also bound vesicular stomatitis virus genomic RNA, and binding required the C-terminal region.

CONCLUSIONS AND RELEVANCE: Porcine TRIM25 restricts vesicular stomatitis virus replication by amplifying type I interferon signaling and directly binding viral RNA.