Birnavirus VP1 proteins form a distinct subgroup of RNA-dependent RNA polymerases lacking a GDD motif. (1/4)
We have cloned and characterized the Drosophila X virus (DXV) genome segment B and its encoded VP1, the putative RNA-dependent RNA polymerase (RdRp) present in the virion. The 2991-bp open reading frame encodes the largest birnavirus VP1 at 977 aa, with a calculated M(r) of 112.8 kDa. As with the VP1 proteins of the type species of the other two genera in the family Birnaviridae, namely, infectious pancreatic necrosis virus (genus Aquabirnavirus) and infectious bursal disease virus (genus Avibirnavirus), the DXV (genus Entomobirnavirus) VP1 protein contains a consensus GTP-binding site and appears to possess self-guanylylation activity. All of the birnavirus VP1 proteins contain conserved RdRp motifs that reside in the catalytic "palm" domain of all classes of polymerases. However, the birnavirus RdRps lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RdRps. All three birnavirus RdRps do contain downstream DD motifs that could function as part of the catalytic triad. These motifs are, however, located in spatially distinct regions of the various birnavirus VP1 proteins. These results suggest that the VP1 proteins of birnaviruses form a defined subgroup of polymerases that either are lacking the conserved RdRp motif VI or have repositioned this motif to different structural regions. (+info)First isolation of an Entomobirnavirus from free-living insects. (2/4)
(+info)Presence of entomobirnaviruses in Chinese mosquitoes in the absence of Dengue virus co-infection. (3/4)
(+info)Novel virus discovery and genome reconstruction from field RNA samples reveals highly divergent viruses in dipteran hosts. (4/4)
(+info)Entomobirnavirus is a genus of non-enveloped, double-stranded RNA viruses in the family Birnaviridae, which primarily infect insects and have a bi-segmented genome.
Entomobirnavirus is a genus of viruses in the Birnaviridae family, which infect insects. These viruses have a bi-segmented double stranded RNA genome and are transmitted horizontally among insect hosts through oral or vertical transmission. Entomobirnaviruses replicate in the cytoplasm of infected cells and are known to cause diseases in certain insect species, such as Drosophila melanogaster (fruit flies). However, they are not known to infect humans or other vertebrate animals.