Paul D. Scotti

Flock house virus: A Nodavirus isolated fromCostelytra zealandica (White) (Coleoptera: Scarabaeida)

SummaryThe physico-chemical properties of Flock House virus (FHV) were examined. FHV was shown to have a single-stranded RNA genome divided between two species of MW 1.1 and 0.46 million; the genome was infectious. FHV has a single. coat protein of 43,000 MW. The virus sediments at 142S and has a density of 1.351 g/ml in CsCl at pH 7. These properties indicate that FHV is a nodavirus but it is distinguishable from Nodamura virus and black beetle virus by differences in electrophoretic mobility, the size of the coat protein, particle density and stability in CsCl.

Cricket paralysis virus and drosophila C virus: serological analysis and comparison of capsid polypeptides and host range.

Abstract Five strains of Drosophila C virus (DCV) were found to be serologically indistinguishable. By using antisera against DVC strains and cricket paralysis virus (CrPV), a relationship was shown to exist between the two viruses. All DCV strains exhibited the same polypeptide profile when analyzed on SDS-polyacrylamide gels and, while basically similar, analysis of CrPV polypeptides revealed that they were slightly larger than those of DCV. Three strains of DCV could be distinguished from each other by their pathogenicity in Drosophila melanogaster or Galleria mellonella , while only CrPV was able to multiply in Gryllus bimaculatus . Also, CrPV but not DCV, could multiply in an established cell line of Lymantria dispar .

Pernin: a novel, self-aggregating haemolymph protein from the New Zealand green-lipped mussel, Perna canaliculus (Bivalvia: Mytilidae).

A protein, designated pernin, found in the New Zealand green-lipped mussel, comprises almost all of the protein in cell-free haemolymph. It occurs as large, aggregate structures of several hundred units resembling small virus-like particles. Pernin is a non-pigmented, glycosylated protein, composed of 497 amino acids, which has an estimated molecular mass of 60 kDa. It is exceptionally rich in histidine (13.7%) and aspartic acid (12.3%), amino acids both known to participate in the binding of divalent metal cations. In addition, pernin has serine protease inhibitor activity, likely due to a sequence of eight N-terminal amino acid residues, separated from the remainder of the protein via a histidine-aspartate spacer. The pernin monomer comprises three regions of obvious sequence duplication. These make up approximately 95% of the pernin molecule and have sequences clearly homologous to the active-site domain of Cu-Zn SODs (superoxide dismutases). Despite several of the metal ion co-ordinating histidine residues being retained, pernin contains no Cu or Zn. It is, however, associated with Fe with an apparent stoichiometry of 1 atom of Fe to 6 molecules of pernin. Since pernin has no demonstrable SOD activity, these SOD-derived sequences presumably have been modified for another function.

Picornalike Viruses of Insects

Over the last 30 years, a large number of small (less than 40 nm in diameter) RNA-containing viruses (SRVs) have been isolated from insects and insect cell cultures, the vast majority of which have undetermined relationships with other animal or plant viruses. Nevertheless, two groups of insect SRVs have been sufficiently well characterized to merit their own families, namely, the nodaviruses and the tetraviruses (Murphy et al.,1995; see also Chapters 8 and 9, this volume). In addition to these two well-characterized families of insect SRVs, there are a number of known birnaviruses from insects (Murphy et al., 1995) and a single calicilike virus (Kellen and Hoffman, 1981; Hillman et al., 1982). The remaining 65 or so viruses are to a large extent relatively uncharacterized (Appendix). However, among these a reasonably large 〞group〞 of viruses exist that have characteristics that superficially resemble those of the mammalian picornaviruses. The mammalian picornaviruses are classically defined by having isometric, unenveloped virions of around 30 nm in diameter, with buoyant densities between 1.30 and 1.46 g/ml, depending on the genus (Table I). The virions contain three major capsid proteins of around 30,000 Da (30 kDa) and another small protein of around 7 kDa. The RNA genome is positive sense, polyadenylated at the 3′ end and has a small protein (VPg) covalently linked to its 5′ end.

Characterisation of cavortin, the major haemolymph protein of the Pacific oyster (Crassostrea gigas)

Abstract Evidence suggests that members of the oyster genus Crassostrea share a common haemolymphprotein. Cavortin, the major haemolymph protein of the Pacific oyster (Crassostrea gigas), comprises 174 amino acid residues totalling 19.4 kDa and is rich in histidine and aspartic acid. The protein consists of a single Cu/Zn SOD (superoxide dismutase) derived domain showing homology to each of the three SOD‐like domains of pernin, the related 60 kDa protein from the green‐lipped mussel (Perna canaliculus). Despite some homology to Cu/Zn SOD sequences we found no compelling evidence that it has retained SOD function. Cavortin has affinity for several divalent cations, particularly iron. Each cavortin monomer is able to bind 8–11 iron ions, but can sequester considerably more iron, presumably by forming spheroid particles. The primary function of cavortin, like pernin, has been altered during the course of evolution, but has yet to be determined unambiguously. A likely role is as a metal ion chaperone.