Rab1A is required for assembly of classical swine fever virus particle

Rab1A belongs to the small Rab GTPase family and is involved in the lifecycle of numerous viruses. Here, knockdown of Rab1A inhibited CSFV growth. Further study revealed that Rab1A depletion decreased intracellular and extracellular CSFV titers, but did not affect intracellular virus genome copies and E2 protein expression within a virus lifecycle, which suggested that Rab1A is required for CSFV particle assembly rather than for genome replication or virion release. This was proofed by blocking the spread of virus using neutralizing antibodies, through which the negative effects of Rab1A knockdown on multi-cycle replication of CSFV were eliminated. Moreover, co-immunoprecipitation and confocal microscopy assays showed that Rab1A bound to CSFV NS5A protein, indicating that Rab1A and viral NS5A proteins may work cooperatively during CSFV particle assembly. In conclusion, this study demonstrated for the first time that Rab1A is required for CSFV particle assembly and binds to viral particle assembly-related NS5A protein.