Insect-virus relationships: Sifting by informatics

Abstract

Several groups of large DNA viruses successfully utilise the rich resource provided by insect hosts. Defining the mechanisms that enable these pathogens to optimise their relationships with their hosts is of considerable scientific and practical importance, but our understanding of the processes involved is, as yet, rudimentary. Here we describe an informatics-based approach that uses comparison of viral genomic sequences to identify candidate genes likely to be specifically involved in this process. We hypothesise that such genes should satisfy two essential criteria, namely, that they should be (i) present in those members of a virus family that infect insects, but absent from those that infect other hosts, and (ii) found in at least two unrelated taxa of insect viruses. These criteria currently identify six groups of viral genes, including one that encodes the fusolin/gp37 proteins. Demonstration that the fusolin/gp37 proteins can enhance oral infectivity of insect viruses provides a primary validation of this approach to the examination of insect-virus relationships.

Variants of open reading frame Bm126 in wild-type Bombyx mori nucleopolyhedrovirus isolates exhibit functional differences

“…Including the previously reported Bm126-T3 (Gomi et al, 1999), it is evident that there exist at least three subtypes of Bm126 in natural BmNPV isolates. It has been reported that there is one or more copies of the 11K protein in baculovirus; for example, there are five copies of the 11K gene in Xestia c-nigrum granulovirus (Dall et al, 2001). This is the first evidence that different subtypes of Bm126 exist in natural baculovirus isolates.…”

“…Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the type species and is the most widely studied of the family Baculoviridae (Ayres et al, 1994). The AcMNPV open reading frame 150 (Ac150) encodes the 11K protein with a hydrophobic N terminus and a Cterminal peritrophin-A domain (Ayres et al, 1994;Dall et al, 2001). Ac150 also encodes a cluster of charged amino acids between the hydrophobic N terminus and the C6 motif (Zhang et al, 2005).…”

“…Ac150 also encodes a cluster of charged amino acids between the hydrophobic N terminus and the C6 motif (Zhang et al, 2005). The 11K proteins are conserved among many baculovirus genomes and, in addition, homologues are found in entomopoxviruses (Dall et al, 2001). The peritrophin-A domain can be represented as CX 7-18 CX 5 CX 6-11 CX 12 CX 5-11 C, where X is any amino acid residue other than cysteine, also referred to as the six-cysteine (C6) motif (Tellam et al, 1999).…”

Evidence for the evolution of ascoviruses from iridoviruses

“…Second, genes acquired must be present in all representative viruses of a lineage, and the proteins they encode must be more similar to each other than to their eukaryotic homologues. This criterion avoids use of marker proteins with features that result from interactions with their eukaryotic hosts (Bugert & Darai, 2000;Dall et al, 2001;Tidona & Darai, 2000). Third, phylogenetic analyses of marker proteins in a sublineage must agree with those of genes used for the study of the complete lineage.…”

The Non-catalytic Chitin-binding Protein CBP21 from Serratia marcescens Is Essential for Chitin Degradation

“…Homologues also occur in insect viruses (named GP37 or fusolin proteins in baculoviruses and entomopoxviruses, respectively; see Ref. 28 and the references therein). It is known that these virus homologues are important for infectiousness (29 -32), and in one case chitin binding has been demonstrated (33).…”