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Currently, there are approximately 6500 species of viruses known in the world, among which more than 1500 are plant viruses. Most of them are capable of causing epiphytoties, which lead to decreased yields, reduced product quality, and sometimes put valuable commercial varieties or even entire plant species at risk of extinction. The global spread of viruses leads to the need to strengthen phytosanitary and quarantine restrictions, which requires additional financial costs. Understanding of viral biology and the principles of its propagation is a key factor in the formation of strategies and methods for combating these pathogens. Among the newest approaches are the genetic engineering technologies. Their use made it possible to create a number of plant varieties with increased resistance to viruses. However, the problem of creating virus-resistant plants still remains one of the most urgent since viruses acquire the ability to bypass defense mechanisms with time and there is a need to obtain new resistant varieties. There are several main approaches for obtaining of transgenic plants with increased resistance to viruses. They are based on RNA interference, resistance associated with viral capsid proteins, RNA-satellites, antisense RNAs, replicases, RNA-dependent RNA polymerase, the action of ribonucleases, ribosome-inactivating proteins, hammerhead ribozymes, miRNAs, plant antibodies, etc. One of the approaches to creating virus-resistant plants is the use of ribonuclease genes. The genes encoding ribonucleases have different origin and belong to a wide range of hosts: bacteria, fungi, plants, and animals. In particular, extracellular ribonucleases are able to cut nonspecifically molecules of viral RNA in apoplast that allows for creating plants with increased resistance to various plant viruses. This review is focused on the study of various genetic engineering approaches and the prospects of their use for the creation of virus-resistant plants. Emphasis is placed on the study of heterologous ribonuclease genes influence. [ABSTRACT FROM AUTHOR]

Bacteriophages or phages are viruses that infect bacterial cells (for the scope of this review we will also consider viruses that infect Archaea). The constant threat of phage infection is a major force that shapes evolution of microbial genomes. To withstand infection, bacteria had evolved numerous strategies to avoid recognition by phages or to directly interfere with phage propagation inside the cell. Classical molecular biology and genetic engineering had been deeply intertwined with the study of phages and host defenses. Nowadays, owing to the rise of phage therapy, broad application of CRISPR-Cas technologies, and development of bioinformatics approaches that facilitate discovery of new systems, phage biology experiences a revival. This review describes variety of strategies employed by microbes to counter phage infection. In the first part defense associated with cell surface, roles of small molecules, and innate immunity systems relying on DNA modification were discussed. The second part focuses on adaptive immunity systems, abortive infection mechanisms, defenses associated with mobile genetic elements, and novel systems discovered in recent years through metagenomic mining. [ABSTRACT FROM AUTHOR]

The disease caused by Tomato zonate spot virus (TZSV), transmitted by Frankliniella occidentalis in a circulative-propagative manner, results in significant loss in production and quality in ornamentals and vegetable crops. Related to this recently found tospovirus (TZSV), knowledge involving the interaction between virus, vector, and host plants remains unknown. In this study, we investigated the effects of TZSV infection on the changes in concentration of the plant hormones jasmonic acid (JA) and salicylic acid (SA), and the transcriptional regulation of JA- and SA-associated genes. Additionally, we verified that JA and SA inhibit the fitness of the vector F. occidentalis. This work brings to a new perspective on plant—virus–vector interactions is proposed, which could be applied to control the TZSV infection. [ABSTRACT FROM AUTHOR]

Viruses are the most numerous and genetically diverse form of life; they are able to interact with any cellular organism. The long-term coexistence of cellular organisms and parasitic viruses has contributed to the emergence and evolution of a variety of strategies to defend host cells from viral infection and of viral counterstrategies to avoid cellular defenses. This review focuses on the issue of the coevolution of systems of innate antiviral defense and adaptive viral mechanisms. [ABSTRACT FROM AUTHOR]

In the present research, we have studied an influence of enhanced expression TRIM14 on alphavirus Sindbis (SINV, Togaviridae family) infection. In the HEK293 cells transfected with human trim14 gene (HEK- trim14), SINV yield after infection was decreased 1000-10,000 times (3-4 lg of TCD50/ml) at 24 h p.i. and considerably less (1-2 lg of TCD50/ml) at 48 h p.i. Analysis of the expression of 43 genes directly or indirectly involved in innate immune machine in HEK- trim14 non-infected cells comparing with the control (non-transfected) HEK293 cells revealed that stable trim14 transfection in HEK293 cells caused increased transcription of 18 genes ( ifna, il6 ( ifnβ2), isg15, raf- 1, NF-kB ( nf- kb1, rela, nf- kb2, relb), grb2, grb3- 3, traf3ip2, junB, c- myb, pu.1, akt1, tyk2, erk2, mek2) and lowered transcription of 3 genes ( ifnγ, gata1, il- 17a). The similar patterns of genes expression observe in SINV-infected non-transfected HEK293 cells. However, SINV infection of HEK- trim14 cells caused inhibition of the most interferon cascade genes as well as subunits of transcription factor NF-κB. Thus, stable enhanced expression of trim14 gene in cells activates the transcription of many immunity genes and suppresses the SINV reproduction, but SINV infection of HEK- trim14 cells promotes inhibition of some genes involved in innate immune system. [ABSTRACT FROM AUTHOR]

Over the last 30 years, aquaculture has become the fastest growing form of agriculture production in the world, but its development has been hampered by a diverse range of pathogenic viruses. During the last decade, a large number of viruses from aquatic animals have been identified, and more than 100 viral genomes have been sequenced and genetically characterized. These advances are leading to better understanding about antiviral mechanisms and the types of interaction occurring between aquatic viruses and their hosts. Here, based on our research experience of more than 20 years, we review the wealth of genetic and genomic information from studies on a diverse range of aquatic viruses, including iridoviruses, herpesviruses, reoviruses, and rhabdoviruses, and outline some major advances in our understanding of virus-host interactions in animals used in aquaculture. [ABSTRACT FROM AUTHOR]

The innate immune system employs a number of pattern recognition receptor families in response to DNAs and RNAs, either from invading microbes or within the hosts. These include the Toll-like receptors (TLRs), the retinoic acid inducible gene I (RIG-I) like receptors (RLRs), and the nucleotide-binding domain leucine-rich repeat/NOD-like receptor (NLRs), among other potential sensors in the cytoplasm. These receptors are composed of modular domain architecture, with ligand binding/sensing domains and signaling domains regulated either through dimerization/oligomerization, or conformational changes directed by enzymatic activities. Signaling pathways from different families of receptors converge on their respective common adapter proteins and lead to activation of transcription factors or caspases. Many of these receptors induce orchestrated responses to similar ligands from different cell types, resulting in redundant and complementary immunity to infections. This highly efficient defense system is a double-edged sword: inappropriate reaction to host ligands leads to compromised innate tolerance and autoimmune diseases. Structural studies of innate immune receptors and their signaling pathways are essential in our understanding of pattern recognition mechanisms and design of more efficient vaccine adjuvants. [ABSTRACT FROM AUTHOR]

We explored the possibility of protecting Penaeus monodon against white spot syndrome virus (WSSV) infection via interference RNA technology by oral administration of bacterially expressed WSSV VP28dsRNA. Shrimp were given dsRNA orally via two methods. In the first method, pellet feed was coated with inactivated bacteria containing overexpressed dsRNA of the WSSV VP28 gene, and in the second method, pellet feed was coated with VP28dsRNA–chitosan complex nanoparticles. The treated shrimp were orally challenged with WSSV by feeding WSSV-infected tissue. The experiment was conducted for 30 days. The dsRNA-treated shrimp challenged with WSSV showed higher survival compared to control shrimp. Sixty-eight percent survival was observed in shrimp fed with feed coated with inactivated bacteria containing dsRNA of the WSSV VP28 gene whereas 37% survival was observed in shrimp fed with VP28dsRNA–chitosan complex nanoparticle–coated feed. The WSSV caused 100% mortality in shrimp fed with pellet feed coated with inactivated bacteria with empty LITMUS38i vector. At the end of the experiment, the tissue samples prepared from randomly selected shrimp that survived were analyzed via reverse transcriptase-polymerase chain reaction and Western blot analysis for WSSV. The samples were negative for WSSV. Based on the present data and the advantages of dsRNA, we believe that oral administration of crude extract of bacterially expressed VP28dsRNA is a potential therapeutic agent against WSSV infection of shrimp. [ABSTRACT FROM AUTHOR]