ICTV Virus Taxonomy Profile: Solemoviridae 2021

The family Solemoviridae includes viruses with icosahedral particles (26–34 nm in diameter) assembled on T=3 symmetry with a 4–6 kb positive-sense, monopartite, polycistronic RNA genome. Transmission of members of the genera Sobemovirus and Polemovirus occurs via mechanical wounding, vegetative propagation, insect vectors or abiotically through soil; members of the genera Polerovirus and Enamovirus are transmitted by specific aphids. Most solemoviruses have a narrow host range. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Solemoviridae, which is available at ictv.global/report/solemoviridae.

ICTV Virus Taxonomy Profile: Geminiviridae 2021

The family Geminiviridae includes viruses with mono- or bipartite single-stranded, circular DNA genomes of 2.5–5.2 kb. They cause economically important diseases in most tropical and subtropical regions of the world. Geminiviruses infect dicot and monocot plants and are transmitted by insect vectors. DNA satellites are associated with some geminiviruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Geminiviridae which is available at ictv.global/report/geminiviridae.

Identification of Autophagy-Related Genes in the Potato Psyllid, Bactericera cockerelli and Their Expression Profile in Response to ‘Candidatus Liberibacter Solanacearum’ in the Gut

Autophagy, also known as type II programmed cell death, is a cellular mechanism of “self-eating”. Autophagy plays an important role against pathogen infection in numerous organisms. Recently, it has been demonstrated that autophagy can be activated and even manipulated by plant viruses to facilitate their transmission within insect vectors. However, little is known about the role of autophagy in the interactions of insect vectors with plant bacterial pathogens. ‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-limited Gram-negative bacterium that infects crops worldwide. Two Lso haplotypes, LsoA and LsoB, are transmitted by the potato psyllid, Bactericera cockerelli and cause damaging diseases in solanaceous plants (e.g., zebra chip in potatoes). Both LsoA and LsoB are transmitted by the potato psyllid in a persistent circulative manner: they colonize and replicate within psyllid tissues. Following acquisition, the gut is the first organ Lso encounters and could be a barrier for transmission. In this study, we annotated autophagy-related genes (ATGs) from the potato psyllid transcriptome and evaluated their expression in response to Lso infection at the gut interface. In total, 19 ATGs belonging to 17 different families were identified. The comprehensive expression profile analysis revealed that the majority of the ATGs were regulated in the psyllid gut following the exposure or infection to each Lso haplotype, LsoA and LsoB, suggesting a potential role of autophagy in response to Lso at the psyllid gut interface.

Alternative splicing landscape of small brown planthopper and different response of JNK2 isoforms to rice stripe virus infection

Alternative splicing (AS) is a frequent posttranscriptional regulatory event occurring in response to various endogenous and exogenous stimuli in most eukaryotic organisms. However, little is known about the effects of insect-transmitted viruses on AS events in insect vectors. The present study used third-generation sequencing technology and RNA sequencing (RNA-Seq) to evaluate the AS response in the small brown planthopper Laodelphax striatellus to rice stripe virus (RSV). The full-length transcriptome of L. striatellus was obtained using single-molecule real-time sequencing technology (SMRT). Posttranscriptional regulatory events, including AS, alternative polyadenylation, and fusion transcripts, were analyzed. A total of 28,175 nonredundant transcript isoforms included 24,950 transcripts assigned to 8,500 annotated genes of L. striatellus , and 5,000 of these genes (58.8%) had AS events. RNA-Seq of the gut samples of insects infected by RSV for 8 d identified 3,458 differentially expressed transcripts (DETs); 2,185 of these DETs were transcribed from 1,568 genes that had AS events, indicating that 31.4% of alternatively spliced genes responded to RSV infection of the gut. One of the c-Jun N-terminal kinase ( JNK ) genes, JNK2 , experienced exon skipping, resulting in three transcript isoforms. These three isoforms differentially responded to RSV infection during development and in various organs. Injection of double-stranded RNAs targeting all or two isoforms indicated that three or at least two JNK2 isoforms facilitated RSV accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors. Importance Alternative splicing (AS) is a regulatory mechanism that occurs after gene transcription. AS events can enrich protein diversity to promote the reactions of the organisms to various endogenous and exogenous stimulations. It is not known how insect vectors exploit AS events to cope with transmitted viruses. The present study used third-generation sequencing technology to obtain the profile of AS events in the small brown planthopper Laodelphax striatellus , which is an efficient vector for rice stripe virus (RSV). The results indicated that 31.4% of alternatively spliced genes responded to RSV infection in the gut of planthoppers. One of the c-Jun N-terminal kinase ( JNK ) genes, JNK2 , produced three transcript isoforms by AS. These three isoforms showed different responses to RSV infection, and at least two isoforms facilitated viral accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors.

The efficiency of methods for catching insects - vectors of vector-borne diseases of animals and their species composition

The article provides the results of study of the effectiveness of collection methods and the taxonomic identification of insects in the regions of Russia. During the research three methods of collecting insects were used: a UV trap, fly strips and a liquid gadfly trap (“death puddle”). The following blood-sucking insects play a key role in the epizootology of transmissible infections - houseflies (Muscidae), black flies (Simuliidae), mosquitoes (Culicidae), biting midges (Ceratopogonidae), gadflies (Tabanidae). There has been obtained new information on the species, territorial and temporal dynamics of the distribution of vectors of lumpy skin disease in cattle in the subjects of the Russian Federation. Data collection of the spatial and temporal spread of the disease visualized using GIS-technologies have been generated on the basis of the statistical reports. As the result of the research, it has been established that in the Nizhny Novgorod region representatives of the Psychodidae family, the percentage of which was 40.9 %, predominate in the nocturnal entomological complex. They are followed by mosquitoes (genus Culex) - 21.6 %, biting midges - 16.4 % manure flies - 7.0 % and black flies - 3.0 %, respectively. In the Saratov region, the nocturnal entomological complex was represented by manure flies (family Sphaeroceridae), black flies (family Simuliidae) and mosquitoes (genus Culex), the percentages were 56,0, 32,0 and 12,0 %, respectively. At the same time, in the Saratov region there were collected 239 times less mosquitoes than in the Nizhny Novgorod region, which was due to an increase in temperature in the conditions of the southern regions. This caused the water bodies to dry out and reduced the pool of insects whose developmental cycle is related to water. It has been established that all-year keeping of cattle in winter cow yards provides the diversity and rise in the number of insect vectors, which increases the risk of lumpy skin disease as compared to the grazing system of cattle keeping. For collection daytime insect vectors, it is recommended to use fly strips covered with rosin and mineral oil. For collection insects of the nocturnal entomocomplex, which are the main transmitters of the lumpy skin disease virus, one should use ultraviolet traps.

Phytoplasma testing in sweet pepper in Moldova

Phytoplasma infects a wide variety of crops, causing considerable economic losses. About half of the vegetable crops damaged by phytoplasma belong to the Solanaceae family including tomato, eggplant and pepper which play an important role in the agriculture economics of Moldova. Our previous research confirmed the presence of ‘Candidatus Phytoplasma solani’ (16SrXII-A subgroup) in tomatoes and also identified insect vectors. In this communication, we present for the first time in Moldova the results of molecular diagnosis of association of ‘Ca. P. solani’ in 4% of the analyzed sweet pepper samples. ‘Ca. P. asteris’ group was absent in the pepper field.

Abundance and diversity of insects associated with dry fish spoilage in three (3) selected markets in Yenagoa, Bayelsa State

The insect vectors associated with spoilage of dried fish in Yenagoa were studied. This was done in order to identify the diversity and abundance of Insects implicated in fish spoilage in order to suggest alternate storage means. Insect infested dry fish samples were procured from Three (3) markets (Swali (A), Kpansia (B) and Tombia (C)) and put into clean transparent plastic containers covered with little nets. They were moistened every day with water sprinkled into the containers for 1 week for insects to emerge. Insect vectors were identified to species level using standard keys. Result of the investigation reveal that a total of eleven Taxa and 156 individuals were found: 12 Calliphorid larvae, 1 crane fly larvae, 46 Musca domestica larvae, 5 Phaenicia sericate, 20 Piophilia casei, 20 Calliphorid pupa, 3 Tephritid larvae, 6 Necrobia fufipe larvae, 10 Dermestes maculatus pupae, 30 Phlorid pupa, 3 scatopsidae larvae. The dominant taxon was Musca domestica larvae followed by Phlorid pupa, and the least abundant was crane fly larvae. From the eleven (11) taxa seen, the abundance of Phlorid pupa was observed in station C (30). Piophilia casei and Musca domestica larvae were the only taxa present in the three sample stations. The Shannon index gotten in station B varied from station A and C. Shannon diversity index for station B was observed to be 1.535 and A and C were observed to be 0.918 and 1.466 respectively. Species evenness was greatest at station A (0.835). The insect vector of the order coleoptera (Beetles) were present only in fish samples from Swali and Tombia markets and absent from fish samples from Kpansia market. This may be due to the storage methods for dry fish in these markets and also due to environmental factors prevalent in these markets. The dominance of Musca domestica is indicative of possible health hazards as the consumption of insect infested dried fish in Yenagoa without washing may result in cholera and diarrhea. The study concluded that insects are the major vector pathogens causing spoilage in dried fish in Yenagoa, as indicated in similar studies in the Niger Delta. Therefore, more effort should be taken in the preservation and storage of dry fish to ensure food safety and security.

Sorting Out the Plague

This chapter explores the complex interactions among mammal hosts, insect vectors, bacteria and even amoebae implicated in the movement of the plague around the world. As it shows, trying to find the cause for the three plague pandemics is similar to the way a television detective solves a murder mystery. While the third pandemic established the roles of rats, rat fleas, and bacteria, that explanation has been incorrectly applied to explain the first two pandemics. The chapter shows how bacterial DNA collected from the teeth of 6th-Century plague victims, exhumed 1,400 years later, established greater understanding of the rate and geographic extent of the plague's spread. It goes on to relate how the age-old conclusions that brown rats were disease reservoirs and their fleas were vectors have been reconsidered, assigning rats and fleas specific roles and recognizing that humans and human lice as host and vector are more consistent with the plague’s rapid spread. Using clues from hosts and vectors to solve the mystery requires investigators to be like detectives.

An Advanced One-Step RT-LAMP for Rapid Detection of little cherry virus 2 Combined with HTS-based Phylogenomics Reveal Divergent Flowering Cherry Isolates

Little cherry virus 2 (LChV-2, genus Ampelovirus) is considered to be the main causal agent of the economically damaging little cherry disease (LChD), which can only be controlled by removal of infected trees. The widespread viral disease of sweet cherry (Prunus avium L.) is affecting the survival of long-standing orchards in North America and Europe, hence the dire need for an early and accurate diagnosis towards a sound disease control strategy. The endemic presence of LChV-2 is mainly confirmed using laborious time-consuming RT-PCR. A rapid RT-LAMP assay targeting a conserved region of the coat protein (CP) was developed and compared with conventional RT-PCR for the specific detection of LChV-2. This affordable assay, combined with a simple RNA extraction, deploys desirable characteristics such as higher ability for faster (<15 min), more analytically sensitive (100-fold) and robust broad-range diagnosis of LChV-2 isolates from sweet cherry, ornamental flowering cherry displaying heterogenous viral etiology and, for the first time, newly-identified potential insect vectors. Moreover, use of Sanger and total RNA High-Throughput Sequencing (HTS) as complementary metaviromics approaches, confirmed the LChV-2 RT-LAMP detection of divergent LChV-2 isolates in new hosts and the relationship of their whole-genome was exhaustively inferred using maximum likelihood phylogenomics. This entails unprecedented critical understanding of a novel evolutionary clade further expanding LChV-2 viral diversity. In conclusion, this highly effective diagnostic platform facilitates strategical support for early in-field testing to reliably prevent dissemination of new LChV-2 outbreaks from propagative plant stocks or newly postulated insect vectors. Validated results and major advantages are herein thoroughly discussed in light of current knowledge ensuing future diagnostic potentials and essential epidemiological considerations to proactively safeguard cherries and Prunus horticultural crop systems from little cherry disease.