Biological activity of Spodoptera exigua nuclear polyhedrosis virus against S. exigua larvae

Smits, P. H.; Vlak, Just M.

doi:10.1016/0022-2011(88)90066-3

Cited by 89 publications

(44 citation statements)

References 25 publications

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“…A significant decrease of the susceptibility with larval age was apparent, a phenomenon that was observed elsewhere for several other baculoviruses (2,8,19,28,34,35). In this context, it is also important to establish complementary methods to monitor the population dynamics of E. aporema, in order to determine the proper timing of application that would ensure control during the early instars of the larvae, when they are more exposed and susceptible to the virus.…”

mentioning

confidence: 67%

Characterization of a Granulovirus Isolated from Epinotia aporema Wals. (Lepidoptera: Tortricidae) Larvae

Sciocco-Cap¹,

Parola

Goldberg³

et al. 2001

Appl Environ Microbiol

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A granulovirus (GV) isolated from Epinotia aporema (Lepidoptera: Tortricidae)-a major soybean pest-was studied in terms of its main morphological, biochemical, and biological properties. The ovoidal occlusion bodies were 466 by 296 nm in size, and their most prominent protein had an apparent molecular mass of 29 kDa. Its amino-terminal sequence was remarkably homologous to that of the granulins of other GVs. The DNA genome size was estimated to be 120 kbp. The high specificity and pathogenicity of this newly described granulovirus (EpapGV) indicate that it is indeed a good candidate for the biological control of this pest.The bean shoot borer, Epinotia aporema (Wals.), is a serious pest of soybean and other legume crops in South America. In Argentina, damages caused by this tortricid decrease soybean yields up to 40%, depending on population level and environmental conditions (18). Currently, broad-spectrum chemical insecticides are used to control this caterpillar, delaying or suppressing field colonization by natural enemies. This scenario compromises the implementation of a proper integrated pest management scheme for soybean crops, in areas where the incidence of E. aporema reaches high population levels (25).Among pathogens, a granulovirus (GV) was detected as the main mortality factor (6, 26). In general, the potential of baculoviruses for pest control has been well documented and they have proven to be effective against many pests (9,15,24). In this regard, preliminary experiments showed that E. aporema GV (EpapGV) could be a safe alternative for inclusion in soybean pest management (25). However, former studies were directed towards evaluating its virulence, and none of the previously cited reports addressed the characterization of the virus. As an initial point in our research, we identified and characterized a GV isolate from E. aporema, indigenous to the main soybean area of Argentina.Virus isolation and multiplication. A colony of E. aporema caterpillars reared on artificial medium (12) was established in our laboratory. EpapGV was isolated from a single E. aporema larva collected in Oliveros (Santa Fe, Argentina). Viral amplification was carried out, allowing fourth-instar larvae to feed on formalin-free artificial diet, superficially contaminated with 4,000 granules per mm 2 . Granules were purified from homogenized larvae by two cycles of centrifugation on continuous 40 to 65% (wt/wt) sucrose gradients at 100,000 ϫ g for 1 h. Virions were released by hydrolyzing granules in 0.1 M Na 2 CO 3 -0.17 M NaCl-0.01 M EDTA (pH 10.5) at 37°C for 30 min. Following the dissolution of the granules, the suspension was neutralized by addition of 1 M HCl, and undissolved material was removed by low-speed centrifugation.Electron microscopy. Tissues were dissected from infected and control larvae, fixed in 3% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.3)-0.25 M sucrose for 3 h, postfixed in 1% osmium tetroxide for 1 h, dehydrated through an ethanolpropylene oxide series, and embedded in Epon-Araldite resin. Ul...

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mentioning

confidence: 67%

Characterization of a Granulovirus Isolated from Epinotia aporema Wals. (Lepidoptera: Tortricidae) Larvae

Sciocco-Cap¹,

Parola

Goldberg³

et al. 2001

Appl Environ Microbiol

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“…S. exigua larvae were reared on an artificial diet at 27 uC, 70 % humidity and a 16 : 8 h photoperiod. Fourth instar S. exigua larvae were infected by contamination of the artificial diet with 4610 5 SeMNPV-US1 (Gelernter & Federici, 1986) polyhedra per larva (Smits & Vlak, 1988). Haemolymph was collected as previously described .…”

Section: Methodsmentioning

confidence: 99%

“…Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) infects the single insect species S. exigua (Smits & Vlak, 1988) and belongs to the group II NPVs. Baculoviruses of this group do not contain a GP64 homologue, but have a functionally homologous F protein as a structural element of the budded virus (BV) .…”

Section: Introductionmentioning

confidence: 99%

Identification of pif-2, a third conserved baculovirus gene required for per os infection of insects

Pijlman

Pruijssers

Vlak

2003

Journal of General Virology

125

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Infection of cultured insect cells with Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) resulted in the generation of mutants with major genomic deletions. Some of the mutants lacked the ability to infect S. exigua larvae per os. The gene(s) responsible for this phenotype in SeMNPV was mapped within a contiguous sequence encoding ORFs 29-35. In this paper we have shown that SeMNPV ORFs 15-35 (including genes encoding cathepsin, chitinase, GP37, PTPT-2, EGT, PKIP-1 and ARIF-1) are not essential for virus replication in cell culture or by in vivo intrahaemocoelic injection. By site-specific deletion mutagenesis of a full-length infectious clone of SeMNPV (bacmid) using ET recombination in E. coli, a series of SeMNPV bacmid mutants with increasing deletions in ORFs 15-35 was generated. Analyses of these mutants indicated that a deletion of SeMNPV ORF35 (Se35) resulted in loss of oral infectivity of polyhedral occlusion bodies. Reinsertion of ORF35 in SeMNPV bacmids lacking Se35 rescued oral infectivity. We propose the name pif-2 for Se35 and its baculovirus homologues (e.g. Autographa californica MNPV ORF22), by analogy to a different gene recently characterized in Spodoptera littoralis NPV, which was designated per os infectivity factor (pif). Similar to the p74 gene, which encodes an essential structural protein of the occlusion-derived virus envelope, pif and pif-2 belong to a group of 30 genes that are conserved among the Baculoviridae. INTRODUCTIONSpodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) infects the single insect species S. exigua (Smits & Vlak, 1988) and belongs to the group II NPVs. Baculoviruses of this group do not contain a GP64 homologue, but have a functionally homologous F protein as a structural element of the budded virus (BV) . BVs are required for the systemic spread of infection throughout the insect, whereas occlusion-derived viruses (ODVs) are involved in the horizontal spread of the virus in insect populations (Blissard & Rohrmann, 1990). Occlusion bodies (OBs) are ingested orally and the alkaline environment of the midgut causes the release of the ODVs. The ODVs first pass the peritrophic membrane and subsequently fuse to the midgut epithelial cells, thereby causing the initial infection (Funk et al., 1997). Large-scale production of SeMNPV for biological control is carried out in vivo using insect larvae, since SeMNPV infection in cell culture leads to the rapid generation and predominance of deletion mutants. These mutants, with deletions up to 25 kb, often lack the ability to infect S. exigua larvae by oral ingestion of OBs (Heldens et al., 1996). Therefore, the genetic engineering of SeMNPV via recombination in cell culture is complicated (Dai et al., 2000) and precludes the in vitro production of biologically active SeMNPV in insect cell bioreactors.Deletions in the SeMNPV genome predominantly occur within the XbaI-A restriction fragment and these deleted genotypes are present in SeMNPV wild-type isolates where they may act as parasitic genotypes (Muñoz et a...

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“…There are few studies where direct comparisons among species have been made, but the propensity for an NPV to be transmitted vertically as an overt infection appears to vary with diVerent hostvirus combinations (Kukan 1999). If there is any trend in patterns of vertical transmission, it would appear that higher levels are seen in more mobile (and often tropical) species, particularly those within the genus Spodoptera (Swaine 1966;Abul-Nasr et al 1979;Smits and Vlak 1988;Fuxa and Richter 1991).…”

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confidence: 95%

Density-related variation in vertical transmission of a virus in the African armyworm

et al. 2007

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Larvae of the African armyworm, Spodoptera exempta, are darker and more resistant to baculovirus infection when reared in groups (gregarious form) compared to being reared singly (solitary form). Lepidoptera that survive virus challenge as larvae could potentially retain a sublethal virus infection which is then transmitted vertically to the next generation. Here we examine whether gregarious and solitary forms of the armyworm differ in the costs of surviving virus infection and in their capacity to transmit an active baculovirus infection to their offspring. Pupae of larvae reared gregariously that survived virus challenge weighed significantly less than uninfected individuals, but this was not so for those reared solitarily. This did not, however, translate into differences in fecundity, at least under laboratory conditions. As found in previous studies, pre-oviposition period was shorter for solitary than gregarious insects, and it was also shorter for females that had been challenged with virus as larvae. Both the prevalence of egg batches containing larvae that died from nucleopolyhedrovirus (NPV) infection and the proportion of infected larvae within each egg batch were significantly increased (approximately doubled) when parental moths were previously challenged with the virus during their larval state. This demonstrates that horizontal transmission in one generation can elevate vertical transmission to the next generation. Moreover, prevalence of overt infection in the offspring generation was two to three times greater when parental moths were reared solitarily as larvae than when reared gregariously. Disease prevalence and proportional infection were both independent of the sex of the infected parent and whether or not the egg batch was surface-sterilized to remove potential contaminants. This suggests that the eggs are infected internally (transovarial) rather than externally (transovum). These results help to shed light on the observed temporal pattern of virus epizootics in eastern Africa.

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Biological activity of Spodoptera exigua nuclear polyhedrosis virus against S. exigua larvae

Cited by 89 publications

References 25 publications

Characterization of a Granulovirus Isolated from Epinotia aporema Wals. (Lepidoptera: Tortricidae) Larvae

Characterization of a Granulovirus Isolated from Epinotia aporema Wals. (Lepidoptera: Tortricidae) Larvae

Identification of pif-2, a third conserved baculovirus gene required for per os infection of insects

Density-related variation in vertical transmission of a virus in the African armyworm

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