Williams, Trevor

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Williams

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Trevor

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Producción Agraria

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  • PublicationOpen Access
    The sf32 unique gene of spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a non-essential gene that could be involved in nucleocapsid organization in occlusion-derived virions
    (Public Library of Science, 2013) Beperet Arive, Inés; Barrera Cubillos, Gloria Patricia; Simón de Goñi, Oihane; Williams, Trevor; López Ferber, Miguel; Gasmi, Laila; Herrero, Salvador; Caballero Murillo, Primitivo; Nekazaritza Ekoizpena; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    A recombinant virus lacking the sf32 gene (Sf32null), unique to the Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV), was generated by homologous recombination from a bacmid comprising the complete viral genome (Sfbac). Transcriptional analysis revealed that sf32 is an early gene. Occlusion bodies (OBs) of Sf32null contained 62% more genomic DNA than viruses containing the sf32 gene, Sfbac and Sf32null-repair, although Sf32null DNA was three-fold less infective when injected in vivo. Sf32null OBs were 18% larger in diameter and contained 17% more nucleocapsids within ODVs than those of Sfbac. No significant differences were detected in OB pathogenicity (50% lethal concentration), speed-of-kill or budded virus production in vivo. In contrast, the production of OBs/larva was reduced by 39% in insects infected by Sf32null compared to those infected by Sfbac. The SF32 predicted protein sequence showed homology (25% identity, 44% similarity) to two adhesion proteins from Streptococcus pyogenes and a single N-mirystoylation site was predicted. We conclude that SF32 is a non-essential protein that could be involved in nucleocapsid organization during ODV assembly and occlusion, resulting in increased numbers of nucleocapsids within ODVs.
  • PublicationOpen Access
    Spodoptera frugiperda multiple nucleopolyhedrovirus as a potential biological insecticide: genetic and phenotypic comparison of field isolates from Colombia
    (Elsevier, 2011-04-24) Barrera Cubillos, Gloria Patricia; Simón de Goñi, Oihane; Villamizar, Laura; Williams, Trevor; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    Thirty-eight isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV), collected from infected larvae on pastures, maize, and sorghum plants in three different geographical regions of Colombia, were subjected to molecular characterization and were compared with a previously characterized Nicaraguan isolate (SfNIC). Restriction endonuclease analysis (REN) using six different enzymes showed two different patterns among Colombian isolates, one profile was particularly frequent (92%) and was named SfCOL. The physical map of SfCOL was constructed and the genome was estimated to be 133.9 kb, with few differences in terms of number and position of restriction sites between the genomes of SfNIC and SfCOL. The PstI-K and PstI-M fragments were characteristic of SfCOL. These fragments were sequenced to reveal the presence of seven complete and two partial ORFs. This region was collinear with SfMNPV sf20–sf27. However, two ORFs (4 and 5) had no homologies with SfMNPV ORFs, but were homologous with Spodoptera exigua MNPV (se21 and se22/se23) and Spodoptera litura NPV (splt20 and splt21). Biological characterization was performed against two different colonies of S. frugiperda, one originating from Colombia and one from Mexico. Occlusion bodies (OBs) of the SfCOL isolate were as potent (in terms of concentration–mortality metrics) as SfNIC OBs towards the Mexican insect colony. However, SfCOL OBs were 12 times more potent for the Colombian colony than SfNIC OBs and three times more potent for the Colombian colony than for the Mexican colony. SfCOL and SfNIC showed a slower speed of kill (by ∼50 h) in insects from the Colombian colony compared to the Mexican colony, which was correlated with a higher production of OBs/larvae. SfCOL is a new strain of SfMNPV that presents pathogenic characteristics that favor its development as the basis for a biopesticide product in Colombia.
  • PublicationOpen Access
    Deletion genotypes reduce occlusion body potency but increase occlusion body production in a Colombian Spodoptera frugiperda nucleopolyhedrovirus population
    (Public Library of Science, 2013) Barrera Cubillos, Gloria Patricia; Williams, Trevor; Villamizar, Laura; Caballero Murillo, Primitivo; Simón de Goñi, Oihane; Nekazaritza Ekoizpena; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    A Colombian field isolate (SfCOL-wt) of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a mixture of different genotypes. To evaluate the insecticidal properties of the different genotypic variants, 83 plaque purified virus were characterized. Ten distinct genotypes were identified (named A through J). SfCOL-A was the most prevalent (71±2%; mean ± SE) showing a PstI restriction profile indistinguishable to that of SfCOL-wt. The remaining nine genotypes presented genomic deletions of 3.8 - 21.8 Kb located mainly between nucleotides 11,436 and 33,883 in the reference genome SfMNPV-B, affecting the region between open reading frames (ORFs) sf20 and sf33. The insecticidal activity of each genotype from SfCOL-wt and several mixtures of genotypes was compared to that of SfCOL-wt. The potency of SfCOL-A occlusion bodies (OBs) was 4.4-fold higher than SfCOL-wt OBs, whereas the speed of kill of SfCOL-A was similar to that of SfCOL-wt. Deletion genotype OBs were similarly or less potent than SfCOL-wt but six deletion genotypes were faster killing than SfCOL-wt. The potency of genotype mixtures cooccluded within OBs were consistently reduced in two-genotype mixtures involving equal proportions of SfCOL-A and one of three deletion genotypes (SfCOL-C, -D or -F). Speed of kill and OB production were improved only when the certain genotype mixtures were co-occluded, although OB production was higher in the SfCOL-wt isolate than in any of the component genotypes, or mixtures thereof. Deleted genotypes reduced OB potency but increased OB production of the SfCOL-wt population, which is structured to maximize the production of OBs in each infected host.