Rab5, an early endosomal protein required for yellow head virus infection of Penaeus monodon

Highlight
• Colocalization between YHV and PmRab5 occurred at 10 min to 3 h post-YHV challenge.
• Silencing of PmRab5 by dsRNA-PmRab5 reduced YHV mRNA and protein levels after YHV infection.
• A delay of shrimp mortality after YHV infection was observed in PmRab5 knockdown shrimp.
• YHV required PmRab5, an early endosomal protein for an early step of YHV infection.

Yellow head virus (YHV) is a virulent pathogen in black tiger shrimp. It causes high mortality within a few days after infection. In this study, colocalization between YHV and P. monodon Rab5 (PmRab5) which is a small GTPase protein was visualized at 10 min to 3 h post-YHV challenge under a confocal microscope. The result indicated that PmRab5 plays a key role in the early stage of endocytosis, and is involved in YHV trafficking process. Molecular cloning showed that the open reading frame of PmRab5 is 633 bp encoding a putative protein of 210 amino acids with an estimated molecular weight of 23 kDa. PmRab5 contained all Rab-specific signature motifs: Rab family motif (RabF), Rab subfamily motif (RabSF), G-boxes and cysteine prenylation signal. Silencing of PmRab5 by specific dsRNA reduced YHV replication inside the cells. Furthermore, lack of PmRab5 expression exhibited a delay of shrimp mortality after YHV infection. The results demonstrated that PmRab5 is involved in YHV early endosomal trafficking, suggesting its role in the early step of infection.Statement of relevanceSilencing of PmRab5 may be applicable for inhibition of YHV.