Grapevine viruses in Mexico: studies and reports

Objective: To contribute to the knowledge of the diversity of viruses and the viral diseases reported in grapevines in Mexico to benefit producers and develop comprehensive viral disease control strategies. Design/methodology/approach: The literature search was conducted in databases such as Scopus, Google Scholar, and EBSCO host, using the following keywords alone or in combination: "virus", "plant", "grapevine", "Mexico". In addition, the INIFAP database was consulted alongside undergraduate and postgraduate dissertation theses. Results: Only one academic file was found published in an indexed international journal using the publication finder software; it corresponds to a grapevine virus report in Mexico. However, taking all the consulted sources, several viral diseases associated with nine grapevine viruses have been reported in Mexico. These species are grouped into seven genera and six families. The reports are from Aguascalientes (56%) and Baja California (44%). Three registered viral species are associated with the leafroll complex, three with rugose wood, one with fleck, one with infectious degeneration, and one with red blotch disease. Findings/conclusions: Several grapevine viruses associated with significant diseases have been reported in Mexico. Unfortunately, most of the reports lack detail and follow-up and are not of international access; therefore, the lack of knowledge in Mexico on this subject is significant. Monitoring the epidemiology of viral diseases in the grapevine is necessary, a national and international relevant crop.Objective: To contribute to the knowledge of the diversity of viruses and the viral diseases reported in grapevines in Mexico, in order to benefit producers and develop comprehensive viral disease control strategies. Design/methodology/approach: The literature search was conducted in databases such as Scopus, Google Scholar, and EBSCO host, using the following keywords alone or in combination: "virus", "plant", "grapevine", and "Mexico". In addition, the INIFAP database was consulted, alongside undergraduate and postgraduate dissertation theses. Results: Only one academic file was found published in an indexed international journal, using the publication finder software; the report corresponds to a grapevine virus present in Mexico. However, based on all the consulted sources, several viral diseases associated with nine grapevine viruses have been reported in Mexico. These species have been grouped into seven genera and six families. The reports come from Aguascalientes (56%) and Baja California (44%). Three registered viral species are associated with the leafroll complex, three with rugose wood, one with fleck, one with infectious degeneration, and one with red blotch disease. Findings/conclusions: Several grapevine viruses associated with major diseases have been reported in Mexico. Unfortunately, most of the reports lack detail and follow-up, and they are not readily available for international researchers; therefore, the lack of knowledge about this subject in Mexico is significant. Monitoring the epidemiology of viral diseases in the grapevine —a national and international relevant crop— is necessary

Substitution of the premembrane and envelope protein genes of Modoc virus with the homologous sequences of West Nile virus generates a chimeric virus that replicates in vertebrate but not mosquito cells

Background: Most known flaviviruses, including West Nile virus (WNV), are maintained in natural transmission cycles between hematophagous arthropods and vertebrate hosts. Other flaviviruses such as Modoc virus (MODV) and Culex flavivirus (CxFV) have host ranges restricted to vertebrates and insects, respectively. The genetic elements that modulate the differential host ranges and transmission cycles of these viruses have not been identified. Methods: Fusion polymerase chain reaction (PCR) was used to replace the capsid (C), premembrane (prM) and envelope (E) genes and the prM-E genes of a full-length MODV infectious cDNA clone with the corresponding regions of WNV and CxFV. Fusion products were directly transfected into baby hamster kidney-derived cells that stably express T7 RNA polymerase. At 4 days post-transfection, aliquots of each supernatant were inoculated onto vertebrate (BHK-21 and Vero) and mosquito (C6/36) cells which were then assayed for evidence of viral infection by reverse transcription-PCR, Western blot and plaque assay. Results: Chimeric virus was recovered in cells transfected with the fusion product containing the prM-E genes of WNV. The virus could infect vertebrate but not mosquito cells. The in vitro replication kinetics and yields of the chimeric virus were similar to MODV but the chimeric virus produced larger plaques. Chimeric virus was not recovered in cells transfected with any of the other fusion products. Conclusions: Our data indicate that genetic elements outside of the prM-E gene region of MODV condition its vertebrate-specific phenotype

Conclusive Evidence of Replication of a Plant Virus in Honeybees Is Lacking

The recent article by Li et al. (1) lacks adequate evidence to support the authors’ assertion that a plant virus propagates or replicates in honeybees. Instead, it is possible that tobacco ringspot virus (TRSV) virions associate with the honeybee and parasitic Varroa mites in the absence of TRSV replication

Lymantria dispar iflavirus 1 (LdIV1), a new model to study iflaviral persistence in lepidopterans

The cell line IPLB-LD-652Y, derived from the gypsy moth (Lymantria dispar L.), is routinely used to study interactions between viruses and insect hosts. Here we report the full genome sequence and biological characteristics of a small RNA virus, designated Lymantria dispar iflavirus 1 (LdIV1), that was discovered to persistently infect IPLB-LD-652Y. LdIV1 belongs to the genus Iflavirus. LdIV1 formed icosahedral particles of approx. 30 nm in diameter and contained a 10 044 nt polyadenylated, positive-sense RNA genome encoding a predicted polyprotein of 2980 aa. LdIV1 was induced by a viral suppressor of RNA silencing, suggesting that acute infection is restricted by RNA interference (RNAi). We detected LdIV1 in all tested tissues of gypsy-moth larvae and adults, but the virus was absent from other L. dispar-derived cell lines. We confirmed LdIV1 infectivity in two of these cell lines (IPLB-LD-652 and IPLB-LdFB). Our results provide a novel system to explore persistent infections in lepidopterans and a new model for the study of iflaviruses, a rapidly expanding group of viruses, many of which covertly infect their hosts

In vivo and in vitro infection dynamics of honey bee viruses

The honey bee (Apis mellifera) is commonly infected by multiple viruses. We developed an experimental system for the study of such mixed viral infections in newly emerged honey bees and in the cell line AmE-711, derived from honey bee embryos. When inoculating a mixture of iflavirids [sacbrood bee virus (SBV), deformed wing virus (DWV)] and dicistrovirids [Israeli acute paralysis virus (IAPV), black queen cell virus (BQCV)] in both live bee and cell culture assays, IAPV replicated to higher levels than other viruses despite the fact that SBV was the major component of the inoculum mixture. When a different virus mix composed mainly of the dicistrovirid Kashmir bee virus (KBV) was tested in cell culture, the outcome was a rapid increase in KBV but not IAPV. We also sequenced the complete genome of an isolate of DWV that covertly infects the AmE-711 cell line, and found that this virus does not prevent IAPV and KBV from accumulating to high levels and causing cytopathic effects. These results indicate that different mechanisms of virus-host interaction affect virus dynamics, including complex virus-virus interactions, superinfections, specific virus saturation limits in cells and virus specialization for different cell types

Transcriptomic responses to diet qualityand viral infection in Apis mellifera

Background Parts of Europe and the United States have witnessed dramatic losses in commercially managed honey bees over the past decade to what is considered an unsustainable extent. The large-scale loss of bees has considerable implications for the agricultural economy because bees are one of the leading pollinators of numerous crops. Bee declines have been associated with several interactive factors. Recent studies suggest nutritional and pathogen stress can interactively contribute to bee physiological declines, but the molecular mechanisms underlying interactive effects remain unknown. In this study, we provide insight into this question by using RNA-sequencing to examine how monofloral diets and Israeli acute paralysis virus inoculation influence gene expression patterns in bees. Results We found a considerable nutritional response, with almost 2000 transcripts changing with diet quality. The majority of these genes were over-represented for nutrient signaling (insulin resistance) and immune response (Notch signaling and JaK-STAT pathways). In our experimental conditions, the transcriptomic response to viral infection was fairly limited. We only found 43 transcripts to be differentially expressed, some with known immune functions (argonaute-2), transcriptional regulation, and muscle contraction. We created contrasts to explore whether protective mechanisms of good diet were due to direct effects on immune function (resistance) or indirect effects on energy availability (tolerance). A similar number of resistance and tolerance candidate differentially expressed genes were found, suggesting both processes may play significant roles in dietary buffering from pathogen infection. Conclusions Through transcriptional contrasts and functional enrichment analysis, we contribute to our understanding of the mechanisms underlying feedbacks between nutrition and disease in bees. We also show that comparing results derived from combined analyses across multiple RNA-seq studies may allow researchers to identify transcriptomic patterns in bees that are concurrently less artificial and less noisy. This work underlines the merits of using data visualization techniques and multiple datasets to interpret RNA-sequencing studies.Ope

Conclusive Evidence of Replication of a Plant Virus in Honeybees Is Lacking

The recent article by Li et al. (1) lacks adequate evidence to support the authors’ assertion that a plant virus propagates or replicates in honeybees. Instead, it is possible that tobacco ringspot virus (TRSV) virions associate with the honeybee and parasitic Varroa mites in the absence of TRSV replication.This article is from mBio 5 (2014): e00985, doi: 10.1128/mBio.00985-14. Posted with permission.</p

Transcriptomic responses to diet quality and viral infection in Apis mellifera

Background: Parts of Europe and the United States have witnessed dramatic losses in commercially managed honey bees over the past decade to what is considered an unsustainable extent. The large-scale loss of bees has considerable implications for the agricultural economy because bees are one of the leading pollinators of numerous crops. Bee declines have been associated with several interactive factors. Recent studies suggest nutritional and pathogen stress can interactively contribute to bee physiological declines, but the molecular mechanisms underlying interactive effects remain unknown. In this study, we provide insight into this question by using RNA-sequencing to examine how monofloral diets and Israeli acute paralysis virus inoculation influence gene expression patterns in bees. Results: We found a considerable nutritional response, with almost 2000 transcripts changing with diet quality. The majority of these genes were over-represented for nutrient signaling (insulin resistance) and immune response (Notch signaling and JaK-STAT pathways). In our experimental conditions, the transcriptomic response to viral infection was fairly limited. We only found 43 transcripts to be differentially expressed, some with known immune functions (argonaute-2), transcriptional regulation, and muscle contraction. We created contrasts to explore whether protective mechanisms of good diet were due to direct effects on immune function (resistance) or indirect effects on energy availability (tolerance). A similar number of resistance and tolerance candidate differentially expressed genes were found, suggesting both processes may play significant roles in dietary buffering from pathogen infection. Conclusions: Through transcriptional contrasts and functional enrichment analysis, we contribute to our understanding of the mechanisms underlying feedbacks between nutrition and disease in bees. We also show that comparing results derived from combined analyses across multiple RNA-seq studies may allow researchers to identify transcriptomic patterns in bees that are concurrently less artificial and less noisy. This work underlines the merits of using data visualization techniques and multiple datasets to interpret RNA-sequencing studies.This article is published as Rutter, Lindsay, Jimena Carrillo-Tripp, Bryony C. Bonning, Dianne Cook, Amy L. Toth, and Adam G. Dolezal. "Transcriptomic responses to diet quality and viral infection in Apis mellifera." BMC genomics 20 (2019): 412. doi: 10.1186/s12864-019-5767-1.</p