Comparative analysis of the genomes of Clostera anastomosis (L.) granulovirus and Clostera anachoreta granulovirus

The Complete Genome of a New Betabaculovirus from Clostera anastomosis

Clostera anastomosis (Lepidoptera: Notodontidae) is a defoliating forest insect pest. Clostera anastomosis granulovirus-B (ClasGV-B) belonging to the genus Betabaculovirus of family Baculoviridae has been used for biological control of the pest. Here we reported the full genome sequence of ClasGV-B and compared it to other previously sequenced baculoviruses. The circular double-stranded DNA genome is 107,439 bp in length, with a G+C content of 37.8% and contains 123 open reading frames (ORFs) representing 93% of the genome. ClasGV-B contains 37 baculovirus core genes, 25 lepidopteran baculovirus specific genes, 19 betabaculovirus specific genes, 39 other genes with homologues to baculoviruses and 3 ORFs unique to ClasGV-B. Hrs appear to be absent from the ClasGV-B genome, however, two non-hr repeats were found. Phylogenetic tree based on 37 core genes from 73 baculovirus genomes placed ClasGV-B in the clade b of betabaculoviruses and was most closely related to Erinnyis ello GV (ErelGV). The gene arrangement of ClasGV-B also shared the strongest collinearity with ErelGV but differed from Clostera anachoreta GV (ClanGV), Clostera anastomosis GV-A (ClasGV-A, previously also called CaLGV) and Epinotia aporema GV (EpapGV) with a 20 kb inversion. ClasGV-B genome contains three copies of polyhedron envelope protein gene (pep) and phylogenetic tree divides the PEPs of betabaculoviruses into three major clades: PEP-1, PEP-2 and PEP/P10. ClasGV-B also contains three homologues of P10 which all harbor an N-terminal coiled-coil domain and a C-terminal basic sequence. ClasGV-B encodes three fibroblast growth factor (FGF) homologues which are conserved in all sequenced betabaculoviruses. Phylogenetic analysis placed these three FGFs into different groups and suggested that the FGFs were evolved at the early stage of the betabaculovirus expansion. ClasGV-B is different from previously reported ClasGV-A and ClanGV isolated from Notodontidae in sequence and gene arrangement, indicating the virus is a new notodontid betabaculovirus.

Proteomic analysis of the occlusion-derived virus of Clostera anachoreta granulovirus

To date, proteomic studies have been performed on occlusion-derived viruses (ODVs) from five members of the family Baculoviridae, genus Alphabaculovirus, but only a single member of the genus Betabaculovirus (Pieris rapae granulovirus). In this study, LC-MS/MS was used to analyse the ODV proteins of Clostera anachoreta granulovirus (ClanGV), another member of the genus Betabaculovirus. The results indicated that 73 proteins, including the products of 27 baculovirus core genes, were present in ClanGV ODVs. This is the largest number of ODV proteins identified in baculoviruses to date. To the best of our knowledge, 24 of these proteins were newly identified as ODV-associated proteins. Twelve of the proteins were shared by all seven of the other baculoviruses that have been analysed by proteomic techniques, including P49, PIF-2, ODV-EC43, P74, P6.9, P33, VP39, ODV-EC27, VP91, GP41, VLF-1 and VP1054. ClanGV shared between 20 and 36 ODV proteins with each of the other six baculoviruses that have been analysed by proteomics. Ten proteins were identified only as ODV components of ClanGV and PrGV: Clan22, Clan27, Clan69, Clan83, Clan84, Clan90, Clan116, Clan94, FGF-3 and ME53, the first seven of which were encoded by betabaculovirus-specific genes. These findings may provide novel insights into baculovirus structure as well as reveal similarities and differences between alphabaculoviruses and betabaculoviruses.

Reaching the melting point: Degradative enzymes and protease inhibitors involved in baculovirus infection and dissemination

Baculovirus infection of a host insect involves several steps, beginning with initiation of virus infection in the midgut, followed by dissemination of infection from the midgut to other tissues in the insect, and finally culminating in "melting" or liquefaction of the host, which allows for horizontal spread of infection to other insects. While all of the viral gene products are involved in ultimately reaching this dramatic infection endpoint, this review focuses on two particular types of baculovirus-encoded proteins: degradative enzymes and protease inhibitors. Neither of these types of proteins is commonly found in other virus families, but they both play important roles in baculovirus infection. The types of degradative enzymes and protease inhibitors encoded by baculoviruses are discussed, as are the roles of these proteins in the infection process.

The complete sequence of the first Spodoptera frugiperda Betabaculovirus genome: a natural multiple recombinant virus

Spodoptera frugiperda (Lepidoptera: Noctuidae) is a major pest in maize crops in Colombia, and affects several regions in America. A granulovirus isolated from S. frugiperda (SfGV VG008) has potential as an enhancer of insecticidal activity of previously described nucleopolyhedrovirus from the same insect species (SfMNPV). The SfGV VG008 genome was sequenced and analyzed showing circular double stranded DNA of 140,913 bp encoding 146 putative ORFs that include 37 Baculoviridae core genes, 88 shared with betabaculoviruses, two shared only with betabaculoviruses from Noctuide insects, two shared with alphabaculoviruses, three copies of own genes (paralogs) and the other 14 corresponding to unique genes without representation in the other baculovirus species. Particularly, the genome encodes for important virulence factors such as 4 chitinases and 2 enhancins. The sequence analysis revealed the existence of eight homologous regions (hrs) and also suggests processes of gene acquisition by horizontal transfer including the SfGV VG008 ORFs 046/047 (paralogs), 059, 089 and 099. The bioinformatics evidence indicates that the genome donors of mentioned genes could be alpha- and/or betabaculovirus species. The previous reported ability of SfGV VG008 to naturally co-infect the same host with other virus show a possible mechanism to capture genes and thus improve its fitness.