Dynein light chain DYNLL1 subunit facilitates porcine circovirus type 2 intracellular transports along microtubules

Microtubule (MT) and dynein motor proteins facilitate intracytoplasmic transport of cellular proteins. Various viruses utilize microtubules and dynein for their movement from the cell periphery to the nucleus. The aim of this study was to investigate the intracellular transport of porcine circovirus type 2 (PCV2) via 8 kDa dynein light chain (DYNLL1, LC8) subunit along the MTs. At 20 μM, vinblastine sulfate inhibited tubulin polymerization resulting in disorganized morphology. In PCV2-infected PK-15 cells, double immunofluorescent labeling showed that the viral particles appeared at the cell periphery and gradually moved to the microtubule organization center (MTOC) at 0−12 hour post inoculation (hpi) while at 20−24 hpi they accumulated in the nucleus. Co-localization between DYNLL1 and PCV2 particles was observed clearly at 8−12 hpi. At 20−24 hpi, most aggregated tubulin had a paracrystalline appearance at the MTOC around the nucleus in vinblastine-treated, PCV2-infected PK-15 cells. Between 12 and 24 hpi, PCV2 particles were still bound to DYNLL1 before they were translocated to the nucleus in both treatments, indicating that vinblastine sulfate had no effect on the protein-protein co-localization. The DYNLL1 binding motif, LRLQT, was found near the C-terminus of PCV2 capsid protein (Cap). Molecular docking analysis confirmed the specific interaction between these residues and the cargo binding site on DYNLL1. Our study clearly demonstrated that dynein, in particular DYNLL1, mediated PCV2 intracellular trafficking. The results could explain, at least in part, the viral transport mechanism by DYNLL1 via MT during PCV2 infection.