A novel virus isolated from the aphid Brevicoryne brassicae with similarity to Hymenoptera picorna-like viruses

Abstract

A novel virus, Brevicoryne brassicae virus (BrBV), has been identified in the cabbage aphid using a method based on the random amplification of encapsidated RNA. The complete sequence of the RNA genome of BrBV has been determined. The positive-strand genomic RNA is 10 161 nt, excluding the 39 poly(A) tail, and contains a single open reading frame (positions 793-9744) encoding a putative polyprotein of 2983 aa. The N-terminal part of the polyprotein shows similarity with the structural proteins of iflaviruses. The C-terminal part possesses consensus sequences of the helicase, cysteine protease and RNA-dependent RNA polymerase similar to those of iflaviruses and other picorna-like viruses. The highest sequence similarity observed was with iflaviruses from honeybee and an endoparasitic wasp. Replication and transmission of BrBV was not dependent on endoparasitic wasp infestation of the aphids.Aphids are major pests of crops and the regulation of aphid populations by pathogens and parasitoid wasp is poorly understood. The aphid viruses sequenced to date include one DNA virus [Myzus persicae densovirus (van Munster et al., 2003)] and four RNA viruses. The latter include aphid lethal paralysis virus (ALPV) (van Munster et al., 2002) and Rhopalosiphum padi virus (RhPV) (Moon et al., 1998), both members of the family Dicistroviridae, which infect a variety of insect hosts, and the unclassified Acyrthosiphon pisum virus (APV) (van der Wilk et al., 1997) together with the closely related rosy apple aphid virus (our unpublished data). These viruses were isolated from laboratory cultures of aphids from which significant quantities of virus could be obtained. However, the spectrum of viruses in laboratory cultures may not reflect that present in nature and also decreases the possibility of detecting viruses that cause pathology. In addition, it is difficult to use field-collected aphids for this purpose because field colonies often contain very few insects. To overcome this problem we have developed a novel approach to amplify viral nucleic acid from a small number of field-collected aphids, which has been used to identify the first aphid iflavirus, Brevicoryne brassicae virus (BrBV). Here we report the complete nucleotide sequence and describe the genome organization of BrBV and evidence that BrBV replicates in B. brassicae.Amplification of the encapsidated RNA was adapted from the procedure described by Allander et al. (2005). Fifty adult B. brassicae aphids (total weight 15 mg), collected from different locations in Warwickshire, UK, during the summer of 2005 and stored at 280 uC, were homogenized with 15 ml 10 mM sodium phosphate buffer, pH 7.5. The homogenate was then centrifuged at 350 g for 10 min in a bench top Eppendorf centrifuge. The debris-free supernatant was filtered through a 0.80/0.22 mm filter (Millipore) and then centrifuged at 45 000 r.p.m. in a Ti80 rotor (Beckman) at 4 u C for 120 min. In order to remove traces of DNA contamination, 100 units of DNase I (Stratagene) were added and the sample was incubate...

Characterization of a novel member of genus Iflavirus in Helicoverpa armigera

“…Previously, some members of Iflavirus don't appear to be lethal to their hosts, such as Kakugo virus (Fujiyuki et al, 2009) and Brevicoryne brassicae virus (Ryabov, 2007). And, some members of Iflavirus are known to be harmful to their hosts by lead to developmental problems and host mortality (van Oers, 2010).…”

A novel virus from Macrosiphum euphorbiae with similarities to members of the family Flaviviridae

“…Some previously identified aphid-infecting viruses were detected in only a proportion of the aphids in a colony (Ryabov, 2007(Ryabov, , 2009. To test the frequency of virusinfected aphids in the M. euphorbiae colony, randomly selected single adult aphids were tested for the presence of the virus.…”

“…These include two DNA viruses, Myzus persicae densovirus (MpDNV) (van Munster et al, 2003b) and Dysaphis plantaginea densovirus (DplDNV) (Ryabov et al, 2009), and five RNA viruses, aphid lethal paralysis virus (ALPV) (van Munster et al, 2002), Rhopalosiphum padi virus (Moon et al, 1998), Acyrthosiphon pisum virus (van der Wilk et al, 1997), Brevicoryne brassicae virus (Ryabov, 2007) and rosy apple aphid virus (RAAV) (Ryabov et al, 2009). While these aphid DNA viruses are around 5 kb in size the RNA viruses are larger, around 10 kb in size.…”

Densovirus induces winged morphs in asexual clones of the rosy apple aphid, Dysaphis plantaginea

“…Several viruses of aphids have been characterized, including Myzus persicae densovirus (10); aphid lethal paralysis virus (11) and Rhopalosiphum padi virus (RhPV) (12), both members of the family Dicistroviridae; an iflavirus Brevicoryne brassicae virus (13); and the unclassified Acyrthosiphon pisum virus (APV) (14). Relatively little is known about the effect of these virus infections on aphid physiology; however, a recent study reported a change in olfactory behavior in response to RhPV infection (15).…”