Salmonid viral haemorrhagic septicaemia virus: fusion-related enhancement of virus infectivity by peptides derived from viral glycoprotein G or a combinatorial library

Abstract

To search for enhancers and/or inhibitors of viral haemorrhagic septicaemia virus (VHSV, a salmonid rhabdovirus) infectivity, a total of 51 peptides from a pepscan of viral envelope protein G, a recombinant peptide from protein G (frg11) and 80 peptide mixtures from an α-helix-favoured combinatorial library were screened. However, contrary to what occurs in many other enveloped viruses, only peptides enhancing rather than inhibiting VHSV infectivity were found. Because some of the enhancer pepscan G peptides and frg11 were derived from phospholipid-binding or fusionrelated regions identified previously, it was suggested that enhancement of virus infectivity might be related to virus-cell fusion. Furthermore, enhancement was significant only when the viral peptides were pre-incubated with VHSV at the optimal low pH of fusion, before being adjusted to physiological pH and assayed for infectivity. Enhancement of VHSV infectivity caused by the preincubation of VHSV with peptide p5 (SAAEASAKATAEATAKG), one of the individual enhancer peptides defined from the screening of the combinatorial library, was independent of the preincubation pH. However, it was also related to fusion because the binding of p5 to protein G induced VHSV to bypass the endosome pathway of infection and reduced the low-pH threshold of fusion, thus suggesting an alternative virus entry pathway for p5-VHSV complexes. Further investigations into VHSV enhancer peptides might shed some light on the mechanisms of VHSV fusion.

Identifying potential virulence determinants in viral haemorrhagic septicaemia virus (VHSV) for rainbow trout

“…The position of this mutation proved interesting. Mas et al (2002) had already described a VHSV enhancer peptide spanning the region between residues 99 and 113 of the G gene and, intriguingly, the mutation detected between isolates tested in the present study fell within this region, occurring at the latter end of this domain. However, analysis of published sequences revealed the DK-4p37 G gene was genetically identical to another rainbow trout virulent Swedish isolate, SE-SVA-14 (accession no.…”

Protection and antibody response induced by intramuscular DNA vaccine encoding for viral haemorrhagic septicaemia virus (VHSV) G glycoprotein in turbot (Scophthalmus maximus)

“…To test the neutralising activity of sera collected in this work, we used an immunostaining focus assay previously developed for the immunodetection of viral haemorrhagic septicaemia virus strain 07.71 [37,39,40]. Therefore to begin with, we tested whether or not the monoclonal antibody (MAb) 2C9 directed towards the N protein of VHSV 07.71 also recognised the N protein of VHSV 860 .…”

VHSV G glycoprotein major determinants implicated in triggering the host type I IFN antiviral response as DNA vaccine molecular adjuvants

“…Transfected cells were then infected with SVCV (multiplicity of infection (MOI) of 2.10 −3 ) in a final volume of 100 L/well of cell culture medium supplemented with 2% FBS. At 24 h post-infection the supernatants from infected cell cultures were harvested and viral yields assessed by an immunostaining focus assay [32]. Briefly, different dilutions of the supernatants from SVCV infected ZF4 cells (from 0.1 to 0.0001) were added to EPC cell monolayers, grown in 96-well plates, at 22 • C for 90 min.…”