Bioinformatical analysis of nuclear localisation sequences in penaeid densoviruses

Nuclear location sequences (NLSs) link proteins to importation molecules for transportation into the nucleus. A bioinformatical search of the penaeid parvoviruses was undertaken to look for NLS. All three ORFs of Penaeus merguiensis densovirus (PmergDNV) have functional NLS whilst only the two non-structural proteins of Penaeus stylirostris densovirus (PstDNV) appear to. In PmergDNV, NS1 has a NLS similar to DNA helicase Q1, NS2 is similar to Dorsal and VP1 is similar to SV40 T-antigen signal. In PstDNV, NS2 has a NLS that is an unrecognised pattern unless it is a monopartite Chelsky signal whilst NS1 has both a Dorsal and minute virus of mouse signals. The capsid protein NLS of PstDNV is likely to be inefficient. Spawner isolated mortality virus has a NLS like DNA helicase Q1. These NLSs affect the nature of inclusion bodies seen with light microscopy, basophilic in PmergDNV; eosinophilic in PstDNV and the site of encapsidation, nuclear in PmergDNV; cytoplasmic in PstDNV as seen with TEM. Many possible NLSs in penaeid parvoviruses are homologues to those in eukaryotic organisms and need to be tested experimentally.