Polypyrimidine tract-binding protein interacts with the 3′ stem-loop region of Japanese encephalitis virus negative-strand RNA

The 3′ stem-loop (SL) region of positive- and negative-strand RNA of Japanese encephalitis virus (JEV), like that of other flaviviruses, may function as cis-acting signals during RNA replication. In order to demonstrate the specific interaction between JEV 3′ SL regions and BHK-21 cellular proteins, we performed gel mobility shift assay and UV-induced cross-linking assay. We identified seven cellular proteins of 110, 87, 67, 45, 38, 34, and 30 kDa that bound to the (+)3′ SL RNA, and eight cellular proteins of 138, 110, 87, 67, 55, 52, 38, and 34 kDa that bound to the (−)3′ SL RNA. The 55 kDa protein was identified as the polypyrimidine tract-binding (PTB) protein by immunoprecipitation assay. These data suggest that the 3′ SL regions of JEV-RNA of both polarities may act as recruiting signals for the components of viral replication complexes including host cell-derived PTB protein.