Williams, Trevor

Profile Picture

Email Address

person.page.identifierURI

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

Birth Date

Job Title

Last Name

Williams

First Name

Trevor

person.page.departamento

Producción Agraria

person.page.instituteName

ORCID

person.page.observainves

1173239

person.page.upna

2621

Name

Filters

2019 - 201912020 - 20222
Reset filters

Settings

Subject: Host range ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    PublicationOpen Access
    Nucleopolyhedrovirus coocclusion technology: a new concept in the development of biological insecticides
    (Frontiers Media, 2022) Williams, Trevor; López Ferber, Miguel; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
    Nucleopolyhedroviruses (NPV, Baculoviridae) that infect lepidopteran pests have an established record as safe and effective biological insecticides. Here, we describe a new approach for the development of NPV-based insecticides. This technology takes advantage of the unique way in which these viruses are transmitted as collective infectious units, and the genotypic diversity present in natural virus populations. A ten-step procedure is described involving genotypic variant selection, mixing, coinfection and intraspecific coocclusion of variants within viral occlusion bodies. Using two examples, we demonstrate how this approach can be used to produce highly pathogenic virus preparations for pest control. As restricted host range limits the uptake of NPV-based insecticides, this technology has recently been adapted to produce custom-designed interspecific mixtures of viruses that can be applied to control complexes of lepidopteran pests on particular crops, as long as a shared host species is available for virus production. This approach to the development of NPV-based insecticides has the potential to be applied across a broad range of NPV-pest pathosystems.
  • Thumbnail Image
    PublicationOpen Access
    Genetic variation and biological activity of two closely related alphabaculoviruses during serial passage in permissive and semi-permissive heterologous hosts
    (MDPI, 2019) Belda García, Isabel María; Beperet Arive, Inés; Williams, Trevor; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
    Phylogenetic analyses suggest that Mamestra brassicae multiple nucleopolyhedrovirus (MbMNPV) and Helicoverpa armigera multiple nucleopolyhedrovirus (HearMNPV) may be strains of the same virus species. Most of the studies comparing their biological activities have been performed in their homologous hosts. A comparison of host range and stability in alternative hosts was performed. The host range of these viruses was compared using high concentrations of inoculum to inoculate second instars of six species of Lepidoptera. One semi-permissive host (Spodoptera littoralis) and one permissive host (S. exigua) were then selected and used to perform six serial passages involving a concentration corresponding to the ~25% lethal concentration for both viruses. Restriction endonuclease analysis showed fragment length polymorphisms in every hostvirus system studied. In S. littoralis, serial passage of MbMNPV resulted in decreased pathogenicity and an increase in speed-of-kill, whereas no significant changes were detected for HearMNPV with respect to the initial inoculum. In contrast, both viruses showed a similar trend in S. exigua. These results highlight the low genetic diversity and a high phenotypic stability of HearMNPV with respect to the original inoculum after six successive passages in both insect hosts. This study concludes that host-baculovirus interactions during serial passage are complex and the process of adaptation to a novel semi-permissive host is far from predictable.
  • Thumbnail Image
    PublicationOpen 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.