Williams, Trevor

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https://academica-e.unavarra.es/handle/2454/50181

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Williams

First Name

Trevor

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Producción Agraria

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1173239

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2621

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Open Access
Functional importance of deletion mutant genotypes in an insect nucleopolyhedrovirus population
(American Society for Microbiology, 2005) Simón de Goñi, Oihane; Williams, Trevor; López Ferber, Miguel; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena
A Nicaraguan isolate of a nucleopolyhedrovirus (SfNIC) that attacks the fall armyworm, Spodoptera frugiperda, survives as a mixture of nine genotypes (SfNIC A to I) that all present genomic deletions, except variant B (complete genotype). Sequencing of cloned restriction fragments revealed that genotypic variants lack between 5 and 16 of the open reading frames present in a contiguous sequence of 18 kb of the SfNIC genome. The absence of oral infectivity of SfNIC-C and -D variants is related to the deletion of the pif and/or pif-2 gene, while that of SfNIC-G remains unexplained. The presence of open reading frame 10, homolog of Se030, also appeared to influence pathogenicity in certain variants. Previous studies demonstrated a significant positive interaction between genotypes B and C. We compared the median lethal concentration of single genotypes (A, B, C, D, and F) and co-occluded genotype mixtures (B+A, B+D, B+F, A+C, and F+C in a 3:1 ratio). Mixtures B+A and B+D showed increased pathogenicity, although only B+D restored the activity of the mixture to that of the natural population. Mixtures of two deletion variants (A+C and F+C) did not show interactions in pathogenicity. We conclude that minority genotypes have an important influence on the overall pathogenicity of the population. These results clearly demonstrate the value of retaining genotypic diversity in virus-based bioinsecticides.
Open Access
Analysis of a naturally-occurring deletion mutant of Spodoptera frugiperda multiple nucleopolyhedrovirus reveals sf58 as a new per os infectivity factor of lepidopteran-infecting baculoviruses
(Elsevier, 2012-10-21) Simón de Goñi, Oihane; Palma Dovis, Leopoldo; Williams, Trevor; López Ferber, Miguel; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua
The Nicaraguan population of Spodoptera frugiperda multiple nucleopolyhedrovirus, SfMNPV-NIC, is structured as a mixture of nine genotypes (A–I). Occlusion bodies (OBs) of SfMNPV-C, -D and -G pure genotypes are incapable of oral transmission; a phenotype which in SfMNPV-C and -D is due to the absence of pif1 and pif2 genes. The complete sequence of the SfMNPV-G genome was determined to identify possible factors involved in this phenotype. Deletions of 4860 bp (22,366–27,225) and 60 bp (119,759–119,818) were observed in SfMNPV-G genome compared with that of the predominant complete genotype SfMNPV-B (132,954 bp). However no genes homologous to previously described per os infectivity factors were located within the deleted sequences. Significant differences were detected in the nucleotide sequence in sf58 gene (unknown function) that produced changes in the amino acid sequence and the predicted secondary structure of the corresponding protein. This gene is conserved only in lepidopteran baculoviruses (alpha- and betabaculoviruses). To determine the role of sf58 in peroral infectivity a deletion mutant was constructed using bacmid technology. OBs of the deletion mutant (Sf58null) were not orally infectious for S. frugiperda larvae, whereas Sf58null rescue virus OBs recovered oral infectivity. Sf58null DNA and occlusion derived virions (ODVs) were as infective as SfMNPV bacmid DNA and ODVs in intrahemocelically infected larvae or cell culture, indicating that defects in ODV or OB morphogenesis were not involved in the loss of peroral infectivity. Addition of optical brightener or the presence of the orally infectious SfMNPV-B OBs in mixtures with SfMNPV-G OBs did not recover Sf58null OB infectivity. According to these results sf58 is a new per os infectivity factor present only in lepidopteran baculoviruses.
Open Access
Use of biocides to minimize microbial contamination in Spodoptera exigua multiple nucleopolyhedrovirus preparations
(Elsevier, 2020-08-13) Presa-Parra, Ehdibaldo; Lasa, Rodrigo; Reverchon, Frédérique; Simón de Goñi, Oihane; Williams, Trevor; Institute for Multidisciplinary Research in Applied Biology - IMAB
The presence of contaminant microbes in baculovirus-based insecticides is regulated by phytosanitary product registration authorities. We aimed to determine whether the abundance of microbes in suspensions of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies (OBs) could be reduced by treatment with a range of biocidal compounds. The diversity of contaminant bacteria was determined by next-generation sequencing of the 16S rRNA gene. Overall, 97.9% of sequences detected were Gammaproteobacteria (mostly Pseudomonas spp. and Enterobacteriaceae) and 2.1% were Firmicutes (mostly Enterococcus spp.). Colloidal silver, benzalkonium chloride and chlorhexidine digluconate were identified as highly effective biocides. Incubation of OB suspensions with high concentrations of colloidal silver (450 mg/l) or benzalkonium chloride (6000 mg/l) resulted in marked reductions in colony forming unit counts over a 180 day period at 4° or 25 °C. Benzalkonium chloride and colloidal silver treatments, at either 4 or 25 °C, did not affect the insecticidal activity of OBs over an 80 day period. However, OB activity decreased following 180 days of treatment by benzalkonium chloride at either 4 or 25 °C, or by colloidal silver at 25 °C, but not at 4 °C. Counts of OBs revealed a significant decrease in OB numbers in benzalkonium chloride-treated suspensions after 180 days at both temperatures, whereas colloidal silver-treated OBs were not affected. Benzalkonium chloride also caused aggregation of OBs at the concentration tested. We conclude that biocidal compounds can markedly reduce the abundance of contaminant microorganisms in OB suspensions, and can be accompanied by reductions in OB infectivity and OB numbers in some circumstances. Future studies should focus on lower concentrations of biocides that do not affect OBs in long-term storage.
Open Access
Baculovirus genetic diversity and population structure
(MDPI, 2025-05-07) López Ferber, Miguel; Caballero Murillo, Primitivo; Williams, Trevor; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute for Multidisciplinary Research in Applied Biology - IMAB
Baculoviruses can naturally regulate lepidopteran populations and are used as biological insecticides. The genetic diversity of these viruses affects their survival and efficacy in pest control. For nucleopolyhedroviruses, occlusion-derived virions and the occlusion body facilitate the transmission of groups of genomes, whereas this is not the case for granuloviruses. We review the evidence for baculovirus genetic diversity in the environment, in the host insect, and in occlusion bodies and virions. Coinfection allows defective genotypes to persist through complementation and results in the pseudotyping of virus progeny that can influence their transmissibility and insecticidal properties. Genetic diversity has marked implications for the development of pest resistance to virus insecticides. We conclude that future research is warranted on the physical segregation of genomes during virus replication and on the independent action of virions during infection. We also identify opportunities for studies on the transmission of genetic diversity and host resistance to viruses.
Open Access
Coocclusion of Helicoverpa armigera single nucleopolyhedrovirus (HearSNPV) and Helicoverpa armigera multiple nucleopolyhedrovirus (HearMNPV): pathogenicity and stability in homologous and heterologous hosts
(MDPI, 2022) Arrizubieta Celaya, Maite; Simón de Goñi, Oihane; Ricarte Bermejo, Adriana; López Ferber, Miguel; Williams, Trevor; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB; Gobierno de Navarra / Nafarroako Gobernua
Helicoverpa armigera single nucleopolyhedrovirus (HearSNPV) is a virulent pathogen of lepidopterans in the genera Heliothis and Helicoverpa, whereas Helicoverpa armigera multiple nu-cleopolyhedrovirus (HearSNPV) is a different virus species with a broader host range. This study aimed to examine the consequences of coocclusion of HearSNPV and HearMNPV on the patho-genicity, stability and host range of mixed-virus occlusion bodies (OBs). HearSNPV OBs were approximately 6-fold more pathogenic than HearMNPV OBs, showed faster killing by approximately 13 h, and were approximately 45% more productive in terms of OB production per larva. For coocclusion, H. armigera larvae were first inoculated with HearMNPV OBs and subsequently inoculated with HearSNPV OBs at intervals of 0-72 h after the initial inoculation. When the interval between inoculations was 12-24 h, OBs collected from virus-killed insects were found to comprise 41¿57% of HearSNPV genomes, but the prevalence of HearSNPV genomes was greatly reduced (3- 4%) at later time points. Quantitative PCR (qPCR) analysis revealed the presence of HearSNPV genomes in a small fraction of multinucleocapsid ODVs representing 0.47¿0.88% of the genomes quan-tified in ODV samples, indicating that both viruses had replicated in coinfected host cells. End-point dilution assays on ODVs from cooccluded mixed-virus OBs confirmed the presence of both viruses in 41.9¿55.6% of wells that were predicted to have been infected by a single ODV. A control exper-iment indicated that this result was unlikely to be due to the adhesion of HearSNPV ODVs to HearMNPV ODVs or accidental contamination during ODV band extraction. Therefore, the dispar-ity between the qPCR and end-point dilution estimates of the prevalence of mixed-virus ODVs likely reflected virus-specific differences in replication efficiency in cell culture and the higher in-fectivity of pseudotyped ODVs that were produced in coinfected parental cells. Bioassays on H. armigera, Spodoptera frugiperda and Mamestra brassicae larvae revealed that mixed-virus OBs were capable of infecting heterologous hosts, but relative potency values largely reflected the proportion of HearMNPV present in each mixed-virus preparation. The cooccluded mixtures were unstable in serial passage; HearSNPV rapidly dominated during passage in H. armigera whereas HearMNPV rapidly dominated during passage in the heterologous hosts. We conclude that mixed-virus coocclusion technology may be useful for producing precise mixtures of viruses with host range properties suitable for the control of complexes of lepidopteran pests in particular crops, although this requires validation by field testing.
Open Access
Lacanobia oleracea nucleopolyhedrovirus (LaolNPV): a new European species of alphabaculovirus with a narrow host range
(Public Library of Science, 2017) Simón de Goñi, Oihane; Erlandson, Martin A.; Frayssinet, Marie; Williams, Trevor; Theilmann, David A.; Volkoff, Anne Nathalie; Caballero Murillo, Primitivo; Nekazaritza Ekoizpena; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, IIQ1406-RI1
During an insect sampling program in alfalfa crops near Montpellier, France in 2011, Lacanobia oleracea larvae were collected that died due to nucleopolyhedrovirus infection (LaolNPV). This virus was subjected to molecular and biological characterization. The virus was a multiple nucleocapsid NPV that showed similar restriction profiles to Mamestra configurata NPV-A (MacoNPV-A) but with significant differences. Polypeptide analysis demonstrated similar proteins in occlusion bodies and occlusion derived virions, to those observed in NPVs from Mamestra spp. Terminal sequencing revealed that the genome organization shared similarity with that of MacoNPV-A. The most homologous virus was MacoNPV-A 90/2 isolate (95.63% identity and 96.47% similarity), followed by MacoNPV-A 90/4 strain (95.37% and 96.26%), MacoNPV-B (89.21% and 93.53%) and M. brassicae MNPV (89.42% and 93.74%). Phylogenetic analysis performed with lef-8, lef-9, polh and a concatenated set of genes showed that LaolNPV and the Mamestra spp. NPVs clustered together with HaMNPV, but with a closer genetic distance to MacoNPV-A strains. The Kimura 2-parameter (K-2-P) distances of the complete genes were greater than 0.05 between LaolNPV and the MbMNPV/MacoNPV-B/HaMNPV complex, which indicates that LaolNPV is a distinct species. K-2-P distances were in the range 0.015±0.050 for comparisons of LaolNPV with MacoNPV-A strains, such that additional biological characteristics should be evaluated to determine species status. While MacoNPV-A was pathogenic to seven lepidopteran species tested, LaolNPV was only pathogenic to Chrysodeixis chalcites. Given these findings, Lacanobia oleracea nucleopolyhedrovirus should be considered as a new species in the Alphabaculovirus genus.
Open Access
Complete genome sequence of five Chrysodeixis chalcites nucleopolyhedrovirus genotypes from a Canary Islands isolate
(American Society for Microbiology, 2013-10-24) Bernal Rodríguez, Alexandra; Williams, Trevor; Muñoz Labiano, Delia; Caballero Murillo, Primitivo; Simón de Goñi, Oihane; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua
The Chrysodeixis chalcites single nucleopolyhedrovirus (ChchSNPV) infects and kills C. chalcites larvae, an important pest of banana crops in the Canary Islands. Five genotypes present in the most prevalent and widespread isolate in the Canary Islands were sequenced, providing genetic data relevant to the genotypic and phenotypic diversity of this virus.
Open Access
Insecticidal traits of variants in a genotypically diverse natural isolate of anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV)
(MDPI, 2023) Parras-Jurado, Ana; Muñoz Labiano, Delia; Beperet Arive, Inés; Williams, Trevor; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
Outbreaks of Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Erebidae), a major pest of soybean, can be controlled below economic thresholds with methods that do not involve the application of synthetic insecticides. Formulations based on natural isolates of the Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) (Baculoviridae: Alphabaculovirus) played a significant role in integrated pest management programs in the early 2000s, but a new generation of chemical insecticides and transgenic soybean have displaced AgMNPV-based products over the past decade. However, the marked genotypic variability present among and within alphabaculovirus isolates suggests that highly insecticidal genotypic variants can be isolated and used to reduce virus production costs or overcome isolate-dependent host resistance. This study aimed to select novel variants of AgMNPV with suitable insecticidal traits that could complement the existing AgMNPV active ingredients. Three distinct AgMNPV isolates were compared using their restriction endonuclease profile and in terms of their occlusion body (OB) pathogenicity. One isolate was selected (AgABB51) from which eighteen genotypic variants were plaque purified and characterized in terms of their insecticidal properties. The five most pathogenic variants varied in OB pathogenicity, although none of them was faster-killing or had higher OB production characteristics than the wild-type isolate. We conclude that the AgABB51 wild-type isolates appear to be genotypically structured for fast speed of kill and high OB production, both of which would favor horizontal transmission. Interactions among the component variants are likely to influence this insecticidal phenotype.
Open 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.
Open Access
Population genetic structure determine the virulence and transmissibility of Spodoptera frugiperda multiple necleopolyhedrovirus
(Elsevier, 2007-12-28) Simón de Goñi, Oihane; Williams, Trevor; López Ferber, Miguel; Taulemesse, Jean-Marie; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
A Nicaraguan isolate of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfNIC) survives as a complex mixture of genotypes (named A to I). The speed of kill, time-mortality distribution, and occlusion body (OB) production of single genotypes (A, B and F) and co-occluded mixtures of genotypes, in a 75% + 25% ratio, were compared to determine the contribution of each genotype to the transmissibility of the viral population. Pure genotypes differed markedly in their speed of kill in second instar S. frugiperda. The speed of kill of SfNIC was attenuated compared to that of the dominant genotype B, indicating that interactions involving two or more genotypes likely determine host killing traits in the virus population. Genotypes A, F and defective genotype C, had no significant effects on the distribution of insect deaths over time when present as minority components in mixtures comprising 75% of genotype B. Similarly, the mortality pattern over time of insects infected by genotype F, the fastest-killing genotype tested, was not affected by the presence of genotypes A or C. Semi-quantitative PCR studies indicated that the genetic composition did not differ significantly between SfNIC-infected insects that died soon (67 h) or late (139 h) after inoculation, suggesting that stability in genotypic composition is important for virus survival. Median OB production per insect was correlated with mean time to death so that attenuated speed of kill of SfNIC resulted in high OB yields. We conclude that (i) minority genotypes play a functional role in determining the timing of mortality of infected hosts and (ii) the genotypic structure of the virus population is stably maintained to maximize the likelihood of survival.