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Examples of attenuated viruses used for cross protection
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Attenuated viruses have been isolated and studied not only as a practical means of controlling virus diseases but also to
gain a molecular understanding of viral virulence and cross protection. They have been isolated from crop fields and generated
through high/low temperature treatment or by mutagens such as nitrous acid and ultraviolet irradiatio...
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... pseudorecombinant RNA virus is one choice for selecting an attenuated virus by the exchange of a viral RNA seg- ment with the corresponding RNA from an attenuated strain in multisegmented viruses including Cucumber mosaic virus (CMV). Some attenuated viruses (strains/ isolates) are listed in Table 1. ...
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... virus genomes have been reported for several tobamoviruses (Table 1; Fig. 1a). In L 11 A, 11 base substi- tutions were located in the genome when compared with the wild-type, severe strain L ( Nishiguchi et al. 1985). ...
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... characterization of an attenuated strain (ToMV-K) ( Yang et al. 2002) showed that two mutations resulted in the production of UGA ochre and UAA opal nonsense codons in the 126-kDa replicase and MP genes, respectively, and that both mutations were shown to have roles in symptom attenuation by producing the truncated forms of the 126 kDa and MP. The attenuated phenotype of a masked strain (M) of TMV (Table 1) has been charac- terized in detail ( Ding et al. 2004;Shintaku et al. 1996). The TMV-M 126-kDa protein is reported to have a reduced level of suppression of RNA silencing, while that of wild- type TMV-U1 has higher suppressive activity. ...
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... listed in Table 1 and Fig. 1c, there are also reports of attenuated potyviruses ( Chiang et al. 2007;Lin et al. 2007b;Yambao et al. 2008). When an attenuated strain (HA5-1) of PRSV was compared with its parent strain HA using an infectious cDNA clone, two amino acid substitutions among three in the C-terminal region of P1 at aa positions 309 and 481, and two of four in HC-Pro at aa positions 753 and 944 of HA5-1 appear to be critical in symptom atten- uation in papaya ( Chiang et al. 2007). ...
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Tobacco mosaic virus (TMV) was the first virus to be studied in detail and for many years TMV and other tobamoviruses, particularly tomato mosaic virus (ToMV) and tobamoviruses infecting pepper (Capsicum spp.), were serious crop pathogens. By the end of the twentieth and for the first decade of the twenty-first century tobamoviruses were under some...
Citations
... Japan has a long history of the development of attenuated viruses, and many studies on viral cross-protection have been reported [19][20][21][22]. In particular, Japanese researchers have developed attenuated viruses belonging to the genera Closterovirus [23,24], Cucumovirus [25][26][27][28], Potyvirus [29][30][31][32][33][34], Tobamovirus [35][36][37][38][39][40][41][42][43][44], and Tospovirus [45] and assessed their cross-protective effects (Table 1). ...
... Traditionally, attenuated viruses have been isolated from naturally occurring mutants or via mutagenesis of wild-type viruses using nitrous acid or ultraviolet (UV) irradiation. Sodium nitrite is a well-known mutagen that deaminates cytosine and adenine to produce uracil and hypoxanthine, while UV irradiation has been used to isolate attenuated viruses that form pyrimidine dimers in DNA and RNA [22,46]. In addition, viruses have been isolated from plants incubated at both low and high temperatures (Table 1). ...
In 1929, it was reported that yellowing symptoms caused by a tobacco mosaic virus (TMV) yellow mosaic isolate were suppressed in tobacco plants that were systemically infected with a TMV light green isolate. Similar to vaccination, the phenomenon of cross-protection involves a whole plant being infected with an attenuated virus and involves the same or a closely related virus species. Therefore, attenuated viruses function as biological control agents. In Japan, many studies have been performed on cross-protection. For example, the tomato mosaic virus (ToMV)-L11A strain is an attenuated isolate developed by researchers and shows high control efficiency against wild-type ToMV in commercial tomato crops. Recently, an attenuated isolate of zucchini yellow mosaic virus (ZYMV)-2002 was developed and registered as a biological pesticide to control cucumber mosaic disease. In addition, attenuated isolates of pepper mild mottle virus (PMMoV), cucumber mosaic virus (CMV), tobacco mild green mosaic virus (TMGMV), melon yellow spot virus (MYSV), and watermelon mosaic virus (WMV) have been developed in Japan. These attenuated viruses, sometimes called plant vaccines, can be used not only as single vaccines but also as multiple vaccines. In this review, we provide an overview of studies on attenuated plant viruses developed in Japan. We also discuss the application of the attenuated strains, including the production of vaccinated seedlings.
... Thus, VSRs are considered to play key roles in determining the pathogenicity, virulence, and disease severity of viral pathogens (Sharma and Ikegami, 2010;Wang et al., 2021). Previous studies have shown that CLRDV-ty has a more potent suppression of RNA silencing activity than CLRDV-at and correlated this difference to their symptom severity (Nishiguchi and Kobayashi, 2011;Agrofoglio et al., 2019). Although the difference in amino acid (aa) sequence of CLRDV-AL encoded P0 protein from the other two strains' P0 proteins was identified (Avelar et al., 2020), its effect on the VSR potency has not yet compared with that of the other strains. ...
Cotton is a multipurpose crop grown globally, including the United States. Cotton leafroll dwarf virus (CLRDV), a phloem-limited virus (Solemoviridae) transmitted by aphids, causes significant economic losses to cotton cultivation. CLRDV strains (CLRDV-typical and atypical) that were previously prevalent in other countries cause severe symptoms leading to high yield loss. Recently, a new isolate of CLRDV (CLRDV-AL) has been characterized from infected cotton plants in Alabama that are often asymptomatic and difficult to detect, implying a low titer and pathogenicity within the host. Different pathogenicity among certain strains within the same species often correlates with both environmental and molecular factors. Thus, better management and control of the vector-borne disease can be achieved by elucidating host-pathogen interaction, such as host immune response and pathogen counter-response. In this study, we demonstrate the ability of CLRDV-AL to suppress a major host defense response known as RNA silencing and compare the potency of silencing suppression to other strains of the same virus. Also, we discuss the difference in pathogenicity among them by evaluating the observations based on the amino acid variation within the functional domain. Our study provides and suggests a future direction for specifying the strategy to mitigate potential cotton disease severity.
... The naturally occurring mild strains, exemplified by the widely used mild strain ZYMV-WK Wang et al., 1991), are obtained after extensive surveys of plants with mild symptoms and careful isolation (Costa & Muller, 1980;Gonsalves & Garnsey, 1989;Spence et al., 1996). Another way is the induction of attenuation by physical treatment, for instance high or low temperature treatment or UV irradiation; the widely used ZYMV-2002 , TMV-P (Goto et al., 1984), and cucumber green mottle mosaic virus (CGMMV SH33b) (Motoyoshi & Nishiguchi, 1988;Nishiguchi & Kobayashi, 2011) were obtained this way. ...
Zucchini yellow mosaic virus (ZYMV) seriously damages cucurbits worldwide. Control of ZYMV by cross-protection has been practised for decades, but selecting useful mild viruses is time-consuming and laborious. Most attenuated potyviruses used for cross-protection do not induce hypersensitive reaction (HR) in Chenopodium quinoa, a local lesion host Chenopodium quinoa. Here, severe ZYMV TW-TN3 tagged with green fluorescent protein (GFP), designated ZG, was used for nitrous acid mutagenesis. From three trials, 11 mutants were identified from fluorescent spots without HR in inoculated C. quinoa leaves. Five mutants caused attenuated symptoms in squash plants. The genomic sequences of these five mutants revealed that most of the nonsynonymous changes were located in the HC-Pro gene. The replacement of individual mutated HC-Pros in the ZG backbone and an RNA silencing suppression (RSS) assay indicated that each mutated HC-Pro is defective in RSS function and responsible for reduced virulence. Four mutants provided high degrees of protection (84%-100%) against severe virus TW-TN3 in zucchini squash plants, with ZG 4-10 being selected for removal of the GFP tag. After removal of the GFP gene, Z 4-10 induced symptoms similar to ZG 4-10 and still provided 100% protection against TW-TN3 in squash, thus is considered not a genetically engineered mutant. Therefore, using a GFP reporter to select non-HR mutants of ZYMV from C. quinoa leaves is an efficient way to obtain beneficial mild viruses for cross-protection. This novel approach is being applied to other potyviruses.
... Cross-protection entirely depends on a viral strain that causes either no symptoms or mild symptoms with low viral capacity, and this strain is called primary virus (52). The primary virus is classified as attenuated and therefore acts as a vaccine (67,96). Citrus tristeza virus, zucchini yellow mosaic virus, papaya ring-spot virus and tomato mosaic virus have all been successfully controlled by this method (89). ...
The worldwide spread of Geminiviruses and its vector has been attributed to the high rate of recombination, mutation, presence of alternate hosts, transport of plant material, global human activity along with global trade, new agricultural practices and climate change; therefore, the most severe viral diseases among crops have grown in almost all regions of the world, including cassava viral diseases in Africa, cotton leaf curl disease in Pakistan, and multiple diseases related to tomatoes, legumes and cucurbits in India and all over the world. Begomovirus is the major and largest genus of Geminiviridae which has shown a worldwide increase in its variations and distribution by affecting previously unaffected plants. The increasing population has augmented the demand for a sustainable agriculture boost, but begomoviruses have become a continual threat to the world’s agriculture. Numerous control strategies have been used for the viral invasion of the world as pathogens but begomoviruses continually overcome the control methods, and this has generated a need to end this competition between researchers and begomoviruses. The present review summarizes all strategies used against begomoviruses and provides a comprehensive comparison among all control methods, their drawbacks, and future insights.
Keywords
geminiviruses; begomoviruses; control strategies; host resistance
... In Japan, sudden outbreaks of the diseases caused by tobamoviruses have often been undergone in various horticultural crops, and have raised awareness of the importance of studies not only on their etiology but also on their epidemiology and control. For some tobamoviruses, e, g., TMV, tomato mosaic virus (ToMV) and CGMMV, molecular and biological properties of attenuated viruses were well characterized (Nishiguchi and Kobayashi 2011;Nishiguchi 2017). An attenuated virus has been used for controlling the mosaic disease of tomatoes caused by ToMV in fields. ...
An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological innovation. Herein, the official changes of virus taxonomy, including the establishment of megataxonomy and amendments of the codes of virus classification and nomenclature, recently made by the International Committee on Taxonomy of Viruses were summarized. The continued efforts of the plant virology community of Japan to index all plant viruses and viroids occurring in Japan, which represent 407 viruses, including 303 virus species and 104 unclassified viruses, and 25 viroids, including 20 species and 5 unclassified viroids, as of October 2021, were also introduced. These viruses and viroids are collectively classified into 81 genera within 26 families of 3 kingdoms ( Shotokuvirae , Orthornavirae , Pararnavirae ) across 2 realms ( Monodnaviria and Riboviria ). This review also overviewed how Japan’s plant virus/viroid studies have contributed to advance virus/viroid taxonomy.
... Later, Salaman (1933) reported that an avirulent strain of PVX protected tobacco White Burley plants against superinfection with a virulent strain. Since then, purposeful infection with mild or attenuated strains has been used in attempts to protect crop plants against infection with more virulent strains, e.g. against Tomato mosaic virus (ToMV) in tomato, Zucchini yellow mosaic virus (ZYMV) in squash and melon, Papaya ringspot virus (PRSV) in papaya, Soybean mosaic virus (SMV) in soybean, CTV in citrus trees and others (reviewed in Gal-On and Shiboleth, 2006;Lecoq and Raccah, 2001;Nishiguchi and Kobayashi, 2011;Ziebell and Carr, 2010). In agricultural practice, an attenuated or low virulent isolate must be artificially introduced into the plant. ...
Double infections of related or unrelated viruses frequently occur in single plants, the viral agents being inoculated into the host plant simultaneously (co-infection) or sequentially (super-infection). Plants attacked by viruses activate sophisticated defence pathways which operate at different levels, often at significant fitness costs, resulting in yield reduction in crop plants. The occurrence and severity of the negative effects depend on the type of within-host interaction between the infecting viruses. Unrelated viruses generally interact with each other in a synergistic manner, whereas interactions between related viruses are mostly antagonistic. These can incur substantial fitness costs to one or both of the competitors. A relatively well-known antagonistic interaction is cross-protection, also referred to as super-infection exclusion. This type of interaction occurs when a previous infection with one virus prevents or interferes with subsequent infection by a homologous second virus. The current knowledge on why and how one virus variant excludes or restricts another is scant. Super-infection exclusion between viruses has predominantly been attributed to the induction of RNA silencing, which is a major antiviral defence mechanism in plants. There are, however, presumptions that various mechanisms are involved in this phenomenon. This review outlines the current state of knowledge concerning the molecular mechanisms behind antagonistic interactions between plant viruses. Harmful or beneficial effects of these interactions on viral and host plant fitness are also characterized. Moreover, the review briefly outlines the past and present attempts to utilize antagonistic interactions among viruses to protect crop plants against destructive diseases.
... The concept of cross-protection refers to the inoculation of a related but mild, or attenuated, virus of plants to confer resistance against subsequent infections by severe virus strains (123,200). It has evolved from an early observation in 1929 that preinfection with an attenuated variant of Tobacco mosaic virus (TMV, a tobamovirus) protects tobacco plants against a severe TMV strain (110). ...
Potyviruses (viruses in the genus Potyvirus, family Potyviridae) constitute the largest group of known plant-infecting RNA viruses and include many agriculturally important viruses that cause devastating epidemics and significant yield losses in many crops worldwide. Several potyviruses are recognized as the most economically important viral pathogens. Therefore, potyviruses are more studied than other groups of plant viruses. In the past decade, a large amount of knowledge has been generated to better understand potyviruses and their infection process. In this review, we list the top 10 economically important potyviruses and present a brief profile of each. We highlight recent exciting findings on the novel genome expression strategy and the biological functions of potyviral proteins and discuss recent advances in molecular plant–potyvirus interactions, particularly regarding the coevolutionary arms race. Finally, we summarize current disease control strategies, with a focus on biotechnology-based genetic resistance, and point out future research directions.
Expected final online publication date for the Annual Review of Phytopathology, Volume 59 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... SIE occurs when a previous infection with one (primary) virus prevents or interferes with subsequent infection by a closely related secondary/ challenge virus (DaPalma et al., 2010;Gal-On and Shiboleth, 2006;González-Jara et al., 2009;Ziebell and Carr, 2010). These vaccine-like treatments have been applied more or less successfully to protect agricultural and horticultural plants against infection with more virulent strains, for example, against ZYMV in squash and melon, tomato mosaic virus (ToMV) in tomato, soybean mosaic virus (SMV) in soybean, PRSV in papaya, and Citrus tristeza virus (CTV) in citrus trees (Folimonova, 2013;Gal-On and Shiboleth, 2006;Lecoq and Raccah, 2001;Nishiguchi and Kobayashi, 2011;Ziebell and Carr, 2010). ...
In agricultural or natural settings, plants are continuously exposed to infection by various pathogens, among which RNA viruses are particularly dangerous because of their high evolutionary potential, combining fast replication and high mutation rates. Many plant viruses have evolved as generalists, often sharing the same hosts. Hence, an individual plant can become infected with more than one virus or viral strain. Viruses invading the same host plant interact with one another in a synergistic, antagonistic, or neutral way. A synergistic interaction results in increased accumulation of one or both of the viruses, thereby enhancing their fitness and competitiveness, but it often imposes devastating effects on the host by eliciting disease symptoms. In contrast, only one co-infector can benefit from an antagonistic interaction, and this activity has mostly negative impacts on multiplication and accumulation of its counterpart, but it can have positive effects on the host. This chapter outlines the current knowledge on facilitative and competitive interactions between unrelated or closely related viruses infecting the same host plant.
... strains [1,2]. It is a promising alternate for plant virus disease control, especially when no resistant cultivar available, and has been used successfully to control a variety of viral diseases [3][4][5][6][7][8]. ...
Cross protection is a promising alternate to control Cucumber green mottle mosaic virus (CGMMV) which is of increasing economic importance to cucurbit production worldwide. One major factor confronting the application of cross protection to control CGMMV is the scarcity of available mild mutants. The objective of this paper was to screen attenuated mutants of CGMMV and evaluate their potential in cross protection. An infectious cDNA clone of CGMMV, pCGMMV, was obtained by cloning intron-containing CGMMV genome to modified pCambia0390 vector with the Cauliflower mosaic virus 35S promoter. Five pCGMMV-derived mutants were obtained via site-directed mutagenesis and inoculated to Nicotiana benthamiana plants for symptom observation. The attenuated CGMMV mutants were evaluated for their efficiency in cross protection. The intron-containing clone pCGMMV induced similar disease symptoms and accumulated similar titres of virus in N. benthamiana plants as wild-type CGMMV. Mutations of aspartic acid at position 89 in the coat protein to alanine (D89A) or glutamic acid at position 1069 in the ORF1/2 read-through protein, in the RNA-dependent RNA polymerase domain to alanine (E1069A) alleviated the symptoms of pCGMMV in N. benthamiana plants significantly. In cross protection assay, the two mutants pCGMMV-CP-D89A and pCGMMV-RdRp-E1069A could prevent the superinfection of CGMMV, with protection efficiency of 91.7% and 100%, respectively. The intron-containing clone pCGMMV was stable and highly infectious. The D89 in the coat protein and E1069 in the RNA-dependent RNA polymerase played an important role in regulating the virulence of CGMMV. Mutants pCGMMV-CP-D89A and pCGMMV-RdRp-E1069A were of great potential in the control of CGMMV via cross protection.
... CGMMV is prevalent particularly in cucurbitaceous crops, such as watermelon, muskmelon, and cucumber (Ainsworth 1935;Dombrovsky et al. 2017;Fletcher et al. 1969;Inoue et al. 1967;Rajamony et al. 1987). An attenuated strain (SH33b) of CGMMV was isolated through nitrous acid, ultraviolet (UV) irradiation, and high-temperature treatment, and it has been used for cross-protection of muskmelon in greenhouses in Japan (Motoyoshi and Nishiguchi 1988;Nishiguchi and Kobayashi 2011;Oosawa 1990). ...
Cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, is a major threat to economically important cucurbit crops worldwide. An attenuated strain (SH33b) derived from a severe strain (SH) of CGMMV caused a reduction in the viral RNA accumulation and the attenuation of symptoms, and it has been successfully used to protect muskmelon plants against severe strains in Japan. In this study, we compared GFP-induced silencing suppression by the 129K protein and the methyltransferase domain plus intervening region (MTIR) of the 129K protein between the SH and SH33b strains. As a result, RNA silencing activity (SSA) in the GFP-silenced plants was inhibited efficiently by the MTIR and 129K protein of SH strain, coincided with drastically reduced accumulation of GFP-specific small interfering RNAs (siRNAs), but not by that of SH33b strain. Furthermore, analyses of siRNA binding capability (SBC) by the MTIR of 129K protein and 129K protein using Electrophoretic Mobility Shift Assay (EMSA) revealed that SBC was found with the MTIR and 129K protein of SH, but not with that of SH33b, suggesting a single amino acid mutation (E to G) in the MTIR is responsible for impaired SSA and SBC of SH33b. These data suggest that a single amino acid substitution in the intervening region of 129K protein of CGMMV resulted in attenuated symptoms by affecting RNA silencing suppression.
