Family: Baculoviridae

Genus: Gammabaculovirus

Distinguishing features

The nucleocapsids are enveloped singly, and multiple virions are assembled into each occlusion body (Figure 1.Gammabaculovirus.). The virus is restricted to the host midgut and causes what was previously described in the literature as “infectious diarrhea”. Genome sequencing analyses of three viruses - Neodiprion lecontei nucleopolyhedrovirus (NeleNPV), Neodiprion sertifer nucleopolyhedrovirus (NeseNPV), and Neodiprion abietis nucleopolyhedrovirus (NeabNPV) - revealed that these viruses do not encode the typical envelope fusion proteins found in other baculoviruses (Arif et al., 2011). This observation has raised the question of whether the budded virus phenotype plays any role in gammabaculovirus biology.

Figure 1.Gammabaculovirus. Transmission electron micrographs of occlusion bodies of the gammabaculovirus Neodiprion abietis nucleopolyhedrovirus (micrograph courtesy of C.J. Lucarotti). Scale bars 0.5 µm; (C) 0.2 µm.

Virion

See discussion under family properties.

Genome organization and replication

In comparison to other baculoviruses, the genomes of members of the genus Gammabaculovirus are relatively low in G+C content (about 33%). The genomes of the three sequenced gammabaculoviruses are collinear except for a large non-syntenic region between the DNA polymerase and polyhedrin genes. This region contains genes and ORFs not shared among the three characterized genomes.

Biology

Gammabaculoviruses of species defined to date infect sawfly larvae of genus Neodiprion, order Hymenoptera, but sawflies of other genera (e.g. Gilpinia) may also contain gammabaculoviruses.

Species demarcation criteria

The three species in this genus are distinguished on the basis of differences in host range and specificity, genome sequence, gene content and gene order. It is unclear if the nucleotide distance-based criteria developed for alpha- and betabaculoviruses can be applied to gammabaculoviruses.

Related, unclassified viruses

Virus names and virus abbreviations are not official ICTV designations.