Tokarev, Y. S. | Search bioRxiv

bioRxiv2022

A new microbiological weapon against lepidopteran pests

Nowadays researchers provide more and more evidence that it is necessary to develop an ecologically friendly approach to pest control. This is reflected in a sharp increase in the value of the biological insecticide market in recent decades. In our study, we found a virus strain belonging to the genus Cypovirus (Reoviridae); the strain was isolated from Dendrolimus sibiricus: that possesses attractive features as a candidate for mass production of biological agents for lepidopteran-pest control. We describe morphological, molecular, and ecological features of the new Cypovirus strain. This strain was found to be highly virulent to D. sibiricus (half-lethal dose is 68 occlusion bodies per second-instar larva) and to have a relatively wide host range (infects representatives of five families of Lepidoptera: Erebidae, Sphingidae, Pieridae, Noctuidae, and Lasiocampidae). The virus strain showed a strong interaction with a nontoxic adjuvant (optical brightener), which decreased the lethal dose for both main and alternative hosts, decreased lethal time, and may expand the host range. Moreover, we demonstrated that the insecticidal features were preserved after passaging through the most economically suitable host. By providing strong arguments for possible usefulness of this strain in pest control, we call on virologists, pest control specialists and molecular biologists to give more attention to the Cypovirus genus, which may lead to new insights in the field of pest control research and may provide significant advantages to compare with baculoviruses and Bacillus thuringiensis products which are nowadays main source of bioinsecticides. Significance statementWithin this article we are describing unique set of features of newly discovered cypovirus strain which possess by significant premises for modern biological insecticides requirements: high potency, universality, true regulating effect, flexible production (possibility to choose host species for production), interaction with enhancing adjuvants, ecologically friendly. Basing on genome alignment we suggest that increasing of host range of new strain is the sequence of evolutionary event which was occurred after coinfection of different CPV species within same host. This finding open new perspective to consider CPVs as perspective agent of biocontrol products.

microbiology↗

bioRxiv2020

Differences in structure and hibernation mechanism highlight diversification of the microsporidian ribosome.

Assembling and powering ribosomes are energy-intensive processes requiring fine-tuned cellular control mechanisms. In organisms operating under strict nutrient limitations, such as pathogenic microsporidia, conservation of energy via ribosomal hibernation and recycling is critical. The mechanisms by which hibernation is achieved in microsporidia, however, remain poorly understood. Here, we present the cryo-EM structure of the ribosome from Paranosema locustae spores, bound by the conserved eukaryotic hibernation and recycling factor Lso2. The microsporidian Lso2 homolog adopts a V-shaped conformation to bridge the mRNA decoding site and the large subunit tRNA binding sites, providing a reversible ribosome inactivation mechanism. Although microsporidian ribosomes are universally highly compacted, the P. locustae ribosome retains several rRNA segments absent in other microsporidia, and represents an intermediate state of rRNA reduction. In one case, the near complete reduction of an expansion segment has resulted in a single bound nucleotide, which acts as an architectural co-factor to stabilize a protein-protein interface. The presented structure highlights the reductive evolution in these emerging pathogens and sheds light on a conserved mechanism for eukaryotic ribosome hibernation.

microbiology↗