scholarly journals Mealybug Transmission of Grapevine Leafroll Viruses: An Analysis of Virus–Vector Specificity

2010 ◽  
Vol 100 (8) ◽  
pp. 830-834 ◽  
Author(s):  
Chi-Wei Tsai ◽  
Adib Rowhani ◽  
Deborah A. Golino ◽  
Kent M. Daane ◽  
Rodrigo P. P. Almeida
Keyword(s):  
Plant Pathogens ◽  
Phylogenetic Analyses ◽  
Virus Vector ◽  
Disease Spread ◽  
Virus Species ◽  
Vector Species ◽  
Vector Transmission ◽  
Planococcus Ficus ◽  
Grapevine Leafroll Disease ◽  
Leafroll Disease

To understand ecological factors mediating the spread of insect-borne plant pathogens, vector species for these pathogens need to be identified. Grapevine leafroll disease is caused by a complex of phylogenetically related closteroviruses, some of which are transmitted by insect vectors; however, the specificities of these complex virus–vector interactions are poorly understood thus far. Through biological assays and phylogenetic analyses, we studied the role of vector-pathogen specificity in the transmission of several grapevine leafroll-associated viruses (GLRaVs) by their mealybug vectors. Using plants with multiple virus infections, several virus species were screened for vector transmission by the mealybug species Planococcus ficus and Pseudococcus longispinus. We report that two GLRaVs (-4 and -9), for which no vector transmission evidence was available, are mealybug-borne. The analyses performed indicated no evidence of mealybug–GLRaV specificity; for example, different vector species transmitted GLRaV-3 and one vector species, Planococcus ficus, transmitted five GLRaVs. Based on available data, there is no compelling evidence of vector–virus specificity in the mealybug transmission of GLRaVs. However, more studies aimed at increasing the number of mealybug species tested as vectors of different GLRaVs are necessary. This is especially important given the increasing importance of grapevine leafroll disease spread by mealybugs in vineyards worldwide.

scholarly journals Transmission of Grapevine Leafroll Viruses by Planococcus ficus (Hemiptera: Pseudococcidae) and Ceroplastes rusci (Hemiptera: Coccidae)

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 999-1002 ◽  
Author(s):  
N. Mahfoudhi ◽  
M. Digiaro ◽  
M. H. Dhouibi
Keyword(s):  
Scale Insect ◽  
Experimental Conditions ◽  
Planococcus Ficus ◽  
Soft Scale ◽  
First Report ◽  
Grapevine Leafroll Disease ◽  
Adult Females ◽  
Leafroll Disease

Grapevine leafroll associated virus-3 (GLRaV-3) and Grapevine leafroll associated virus-5 (GLRaV-5), two members of the genus Ampelovirus associated with grapevine leafroll disease, were transmitted by the mealybug Planococcus ficus and the soft scale insect Ceroplastes rusci from infected to healthy vines under experimental conditions. The efficiencies of transmission of GLRaV-3 and GLRaV-5 by P. ficus were 23.3 and 8.3%, respectively, and by C. rusci were 3.3 and 1.7%, respectively. Juvenile instars of P. ficus were more efficient in transmission of the viruses than adult females. This is the first report of the ability of C. rusci to transmit these viruses to grapevines.

scholarly journals Epidemiology and Genetic Diversity of Grapevine Leafroll-Associated Viruses in British Columbia

Plant Disease ◽  
2017 ◽  
Vol 101 (12) ◽  
pp. 2088-2097 ◽  
Author(s):  
S. Poojari ◽  
J. Boulé ◽  
N. DeLury ◽  
D. T. Lowery ◽  
M. Rott ◽  
...  
Keyword(s):  
British Columbia ◽  
Scale Insects ◽  
Disease Spread ◽  
Virus Species ◽  
Relative Incidence ◽  
Growing Seasons ◽  
The Family ◽  
Leafroll Disease ◽  
Composite Samples

Grapevine leafroll disease (GLD) is a complex associated with one or more virus species belonging to the family Closteroviridae. The majority of viruses in this complex are vectored by one or more species of mealybugs (Pseudococcidae) and/or scale insects (Coccidae). Grape-growing regions of British Columbia (BC), including Okanagan, Similkameen, and Fraser valleys and Kamloops (BC central interior), Vancouver, and Gulf islands, were surveyed during the 2014 and 2015 growing seasons for the presence of four major grapevine leafroll-associated viruses, including Grapevine leafroll-associated virus 1 (GLRaV-1), GLRaV-2, GLRaV-3, and GLRaV-4. In total, 3,056 composite five-vine samples were collected from 153 Vitis vinifera and three interspecific hybrid vineyard blocks. The results showed GLRaV-3 to be the most widespread, occurring in 16.7% of the composite samples, followed by GLRaV-4 (3.9%), GLRaV-1 (3.8%), and GLRaV-2 (3.0%). Mixed infections of two or more GLRaVs were found in 4.1% of the total samples. The relative incidence of GLRaVs differed among regions and vineyard blocks of a different age. Characterization of partial CO1 region from a total of 241 insect specimens revealed the presence of Pseudococcus maritimus, Parthenolecanium corni, and other Pulvinaria sp. in BC vineyards. Spatial patterns of GLRaV-3 infected grapevines in three vineyard blocks from three different regions in the Okanagan Valley showed variable degrees of increase in disease spread ranging from 0 to 19.4% over three growing seasons. Regional differences in the relative incidence and spread of GLD underline the need for region-based management programs for BC vineyards.

Control of Grapevine Leafroll Disease Spread at a Commercial Wine Estate in South Africa: A Case Study

2013 ◽  
Vol 64 (2) ◽  
pp. 296-305 ◽  
Author(s):  
G. Pietersen ◽  
N. Spreeth ◽  
T. Oosthuizen ◽  
A. van Rensburg ◽  
M. van Rensburg ◽  
...  
Keyword(s):  
South Africa ◽  
Disease Spread ◽  
Grapevine Leafroll Disease ◽  
Leafroll Disease

Identification of mealybugs, soft scale insects and their predators in vineyards across the savannah agro-ecological region of Nigeria

2021 ◽  
Vol 18 (1) ◽  
pp. 27-32
Author(s):  
A.M. Zongoma ◽  
D.B. Dangora ◽  
M. Sétamou ◽  
M.D. Alegbejo ◽  
O.J. Alabi
Keyword(s):  
Natural Enemies ◽  
Integrated Management ◽  
Scale Insects ◽  
Disease Spread ◽  
Universal Primers ◽  
Grapevine Virus ◽  
Maconellicoccus Hirsutus ◽  
Anagyrus Kamali ◽  
Leafroll Disease ◽  
Ecological Region

Insect-vectored viruses are a major threat to grapevine production but there is a dearth of information on the occurrence and distribution of key grapevine pests in Nigeria. The recent detection of grapevine leafroll associated virus-1 (GLRaV-1), a known insect-vectored ampelovirus, in Nigeria elevates the importance of the identification of its potential vectors as a precursor to assessing the risk of grapevine leafroll disease spread. This study was conducted to determine the occurrence and diversity of potential vectors of grapevine viruses and their natural enemies in vineyards across the savannah agro-ecological region of Nigeria. Forty vineyard and nursery locations were surveyed during 2016 and 45 arthropod samples were collected. The samples were first morphologically identified, and DNA barcoding was conducted on a subset of 16 representative samples using universal primers specific to the Mitochondrial Cytochrome Oxidase subunit I (mtCOI) gene of most insects. The results indicated the presence of two species of scale insects (Parasaissetia nigra and Saissetia coffeae) and two mealybug species (Maconellicoccus hirsutus and Ferrisia virgata), some ofwhich are potential grapevine virus vectors, in Nigerian vineyards. In addition, the natural enemies of these insect species were detected which includes three species of parasitoids (Anagyrus kamali, Anagyrus pseudococci and Encarsia inaron) and one predator (Hyperaspidius mimus). While the detection of mealybugs and scale insects underscore the risk of vector-mediated virus spread in Nigerian vineyards, the identification of their natural enemies indicates presence of natural biological control agents to facilitate an integrated management of economically important grapevine virus diseases in the country. Keywords: Mealybugs; scale insects; parasitoids and predators; insect vectors; grapevine viruses.

scholarly journals Caractérisation génétique des virus Tilligerry et Mitchell River

2009 ◽  
Vol 62 (2-4) ◽  
pp. 151
Author(s):  
M. Belaganahalli ◽  
S. Maan ◽  
P. P.C. Mertens
Keyword(s):  
Reverse Genetics ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Taxonomic Status ◽  
Cross Reactivity ◽  
Emerging Diseases ◽  
Full Length ◽  
Virus Species ◽  
Livestock Farming

Viruses that are normally safely contained within their host spe­cies can emerge due to intense livestock farming, trade, travel, climate change and encroachment of human activities into new environments. The unexpected emergence of bluetongue virus (BTV), the prototype species of the genus Orbivirus, in economi­cally important livestock species (sheep and cattle) across the whole of Europe (since 1998), indicates that other orbiviruses represent a potential further threat to animal and human popula­tions in Europe and elsewhere. The genus Orbivirus is the largest within the family Reoviridae, containing 22 virus species, as well as 14 unclassified orbiviruses, some of which may repre­sent additional or novel species. The orbiviruses are transmitted primarily by arthropod vectors (e.g. Culicoides, mosquitoes or ticks).  Viral genome sequence data provide a basis for virus taxonomy and diagnostic test development, and make it possible to address fundamental questions concerning virus biology, pathogenesis, virulence and evolution, that can be further explored in mutation and reverse genetics studies. Genome sequences also provide criteria for the classification of novel isolates within individual Orbivirus species, as well as the identification of different sero­types, topotypes, reassortants and even closely related but dis­tinct virus lineages.  Full-length genome characterization of Tilligerry virus (TILV), a member of the Eubenangee virus species, and Mitchell River virus (MRV), a member of the Warrego virus species, have revealed highly conserved 5’ and 3’ terminal hexanucleotide sequences. Phylogenetic analyses of orbivirus T2 ‘sub-core-shell’ protein sequences reinforce the hypothesis that this protein is an important evolutionary marker for these viruses. The T2 protein shows high levels of amino acid (AA) sequence identity (> 91%) within a single Orbivirus species / serogroup, which can be used for species identification. The T2-protein gene has therefore been given priority in sequencing studies. The T2 protein of TILV is closely related to that of Eubenangee virus (~91% identity), con­firming that they are both members of the same Eubenangee virus species. Although TILV is reported to be related to BTV in serological assays, the TILV T2 protein shows only 68-70% AA identity to BTV. This supports its current classification within a different serogroup (Eubenangee).  Warrego virus and MRV are currently classified as two distinct members (different serotypes) within the Warrego virus species. However, they show only about 79% AA identity in their T2 pro­tein (based on partial sequences). It is therefore considered likely that they could be reclassified as members of distinct Orbivirus species. The taxonomic classification of MRV will be reviewed after generating full length sequences for the entire genomes of both viruses. The taxonomic status of each of these viruses will also be tested further by co-infections and attempts to create reassortants between them (only viruses belonging to the same species can reassort their genome segments). TILV and MRV are the first viruses from their respective serogroups / virus species to be genetically fully characterized, and will provide a basis for the further characterization / identification of additional viruses within each group / species. These data will assist in the devel­opment of specific diagnostic assays and potentially in control of emerging diseases. The sequences generated will also help to evaluate current diagnostic [reverse transcriptase - polymerase chain reaction (RT-PCR)] tests for BTV, African horse sickness virus, epizootic haemorrhagic disease virus, etc., in silico, by identifying any possibility of cross reactivity.

scholarly journals Phylogenetic and Demographic Characterization of Directed HIV-1 Transmission Using Deep Sequences from High-Risk and General Population Cohorts/Groups in Uganda

Viruses ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 331 ◽  
Author(s):  
Nicholas Bbosa ◽  
Deogratius Ssemwanga ◽  
Alfred Ssekagiri ◽  
Xiaoyue Xi ◽  
Yunia Mayanja ◽  
...  
Keyword(s):  
High Risk ◽  
General Population ◽  
Lake Victoria ◽  
Phylogenetic Analyses ◽  
Sub Saharan Africa ◽  
Transmission Dynamics ◽  
Disease Spread ◽  
Male Participant ◽  
Population Sampling ◽  
Hiv 1

Across sub-Saharan Africa, key populations with elevated HIV-1 incidence and/or prevalence have been identified, but their contribution to disease spread remains unclear. We performed viral deep-sequence phylogenetic analyses to quantify transmission dynamics between the general population (GP), fisherfolk communities (FF), and women at high risk of infection and their clients (WHR) in central and southwestern Uganda. Between August 2014 and August 2017, 6185 HIV-1 positive individuals were enrolled in 3 GP and 10 FF communities, 3 WHR enrollment sites. A total of 2531 antiretroviral therapy (ART) naïve participants with plasma viral load >1000 copies/mL were deep-sequenced. One hundred and twenty-three transmission networks were reconstructed, including 105 phylogenetically highly supported source–recipient pairs. Only one pair involved a WHR and male participant, suggesting that improved population sampling is needed to assess empirically the role of WHR to the transmission dynamics. More transmissions were observed from the GP communities to FF communities than vice versa, with an estimated flow ratio of 1.56 (95% CrI 0.68–3.72), indicating that fishing communities on Lake Victoria are not a net source of transmission flow to neighboring communities further inland. Men contributed disproportionally to HIV-1 transmission flow regardless of age, suggesting that prevention efforts need to better aid men to engage with and stay in care.

scholarly journals Comparative Genomics and Phylogenetic Analyses Suggest Several Novel Species within the Genus Clavibacter, Including Nonpathogenic Tomato-Associated Strains

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Ebrahim Osdaghi ◽  
Touraj Rahimi ◽  
S. Mohsen Taghavi ◽  
Maryam Ansari ◽  
Sadegh Zarei ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Comparative Genomics ◽  
Plant Pathogens ◽  
Phylogenetic Analyses ◽  
Taxonomic Status ◽  
Sensu Stricto ◽  
Bacterial Canker ◽  
Agricultural Crops ◽  
Content Type ◽  
Canker Disease

ABSTRACT Members of the genus Clavibacter are economically important bacterial plant pathogens infecting a set of diverse agricultural crops (e.g., alfalfa, corn, potato, tomato, and wheat). Tomato-associated Clavibacter sp. strains account for a great portion of the genetic diversity of the genus, and C. michiganensis sensu stricto (formerly C. michiganensis subsp. michiganensis), causing bacterial canker disease, is considered one of the most destructive seed-borne agents for the crop worldwide. However, current taxonomic descriptions of the genus do not reflect the existing diversity of the strains, resulting in unsatisfactory results in quarantine surveys for the pathogens. In this study, we used all the available genome sequences of Clavibacter sp. strains, including the type strains of newly described subspecies, to provide precise insight into the diversity of tomato-associated members of the genus and further clarify the taxonomic status of the strains using genotypic and phenotypic features. The results of phylogenetic analyses revealed the existence of nine hypothetical new species among the investigated strains. None of the three new subspecies (i.e., C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis, and C. michiganensis subsp. phaseoli) is included within the tomato-pathogenic C. michiganensis sensu stricto lineage. Although comparative genomics revealed the lack of chp and tomA pathogenicity determinant gene clusters in the nonpathogenic strains, a number of pathogenicity-related genes were noted to be present in all the strains regardless of their pathogenicity characteristics. Altogether, our results indicate a need for a formal taxonomic reconsideration of tomato-associated Clavibacter sp. strains to facilitate differentiation of the lineages in quarantine inspections. IMPORTANCE Clavibacter spp. are economically important bacterial plant pathogens infecting a set of diverse agricultural crops, such as alfalfa, corn, pepper, potato, tomato, and wheat. A number of plant-pathogenic members of the genus (e.g., C. michiganensis sensu stricto and C. sepedonicus, infecting tomato and potato plants, respectively) are included in the A2 (high-risk) list of quarantine pathogens by the European and Mediterranean Plant Protection Organization (EPPO). Although tomato-associated members of Clavibacter spp. account for a significant portion of the genetic diversity in the genus, only the strains belonging to C. michiganensis sensu stricto (formerly C. michiganensis subsp. michiganensis) cause bacterial canker disease of tomato and are subjected to the quarantine inspections. Hence, discrimination between the pathogenic and nonpathogenic Clavibacter sp. strains associated with tomato seeds and transplants plays a pivotal role in the accurate detection and cost-efficient management of the disease. On the other hand, detailed information on the genetic contents of different lineages of the genus would lead to the development of genome-informed specific detection techniques. In this study, we have provided an overview of the phylogenetic and genomic differences between the pathogenic and nonpathogenic tomato-associated Clavibacter sp. strains. We also noted that the taxonomic status of newly introduced subspecies of C. michiganensis (i.e., C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis, and C. michiganensis subsp. phaseoli) should be reconsidered.

scholarly journals Detection and first molecular characterisation of three picornaviruses from diarrhoeic calves in Turkey

2019 ◽  
Vol 67 (3) ◽  
pp. 463-476
Author(s):  
Hakan Işidan ◽  
Turhan Turan ◽  
Mustafa Ozan Atasoy ◽  
Ibrahim Sözdutmaz ◽  
Bünyamin Irehan
Keyword(s):  
Molecular Detection ◽  
Phylogenetic Analyses ◽  
Virus Species ◽  
Specific Primer ◽  
Bovine Enterovirus ◽  
Calf Diarrhoea ◽  
Faecal Samples ◽  
Novel Variants ◽  
Reliable Detection ◽  
Pcr Products

The involvement of picornaviruses in calf diarrhoea was evaluated by the analysis of 127 faecal samples collected from diarrhoeic calves during 2014–2016. Virus detections were carried out by PCR using generic or specific primer pairs. One-third of the faecal samples (33.86%) were found to be positive for one or more of the studied viruses. Bovine kobuvirus was detected in 22.83%, bovine hungarovirus in 11.02%, while bovine enterovirus 1 in 5.51% of the samples. The sequences of the PCR products indicated the existence of novel variants in all the three virus species. When comparing the partial sequences, the nucleotide sequence identities between our newly detected viruses and those previously deposited to the GenBank ranged between 76 and 99%. Phylogenetic analyses revealed a novel lineage within the species Hunnivirus A. Our findings suggest that these viruses should be regarded as possible aetiological agents of calf diarrhoea. Based on the newly determined sequences, we designed and tested a new generic PCR primer set for the more reliable detection of bovine hungaroviruses. This is the first report on the molecular detection of the presence of bovine hungarovirus, bovine kobuvirus and bovine enterovirus 1 in the faecal samples of diarrhoeic calves in Turkey.

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