Synthetic peptides reveal a phospholipid binding domain in the glycoprotein of VHSV, a salmonid rhabdovirus.

Using phosphatidylserine (PS) binding to solid-phase synthetic 15-aa peptides, which covered the full length glycoprotein G of a salmonid rhabdovirus, viral haemorrhagic septicaemia virus (VHSV), evidence is presented showing the mapping of its major phospholipid-binding region. Three overlapping peptides were the dominant but not exclusive, reactive peptides that defined the phospholipid-binding main region. A 28-aa synthetic peptide (p2, aa 82-109), defined by the sequences of the 3 above-mentioned peptides, contained a putative alpha-helix domain with 3 consecutive hydrophobic amino acid a-d heptad-repeats (amphipathic alpha-helix), and 2 arginines at its carboxy terminal part. This peptide showed a higher apparent specific activity of PS-binding than the 15-aa peptides. Only native, denatured or recombinant fragment G4 viral glycoprotein G showed PS-binding. This did not occur for any of the other VHSV proteins tested. The highest specific activity of PS-binding, however, was found for purified VHSV. PS-binding to purified VHSV was abolished by any VHSV treatment that removed the glycoprotein G from the virions and was partially inhibited by anti-p2 mouse antibodies. It was higher at pH 5.6 than at pH 7.6. The identification of the fish rhabdovirus main phospholipid binding domain allowed some preliminary comparative sequence studies that showed that p2-like sequences exist in all rhabdoviruses.