Major Citrus Viruses in Japan
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Abstract:
Citrus species grown in Japan are affected by three major viruses: satsuma dwarf virus (SDV), citrus tatter leaf virus (CTLV, apple stem grooving virus), and citrus tristeza virus (CTV). SDV has spread to other countries, such as China, Korea, and Turkey, apparently through unchecked budwoods and nursery trees; it is natural to assume that some of these contaminated plants harbored CTLV and CTV as well. Thus, citrus viruses in Japan are not only a domestic problem, they are also transboundary threats to agricultural production. This article reviews the occurrence and history of SDV, CTLV, and CTV in Japan as well as recent research developments in Japan and other countries.Keywords:
Citrus tristeza virus
ABSTRACT Prunus necrotic ringspot and apple mosaic viruses have been described separately but they are distantly related serologically and intermediate strains occur in hop and rose. They may therefore be regarded as type strains of two serotypic groups of a single virus ( Prunus necrotic ringspot virus which was the first to be described). The host range of both serotypes is wide, mostly amongst woody plants and there have long been recurring difficulties of diagnosis based on symptoms produced in woody or herbaceous indicator plants. These problems have been overcome by the application of enzyme‐linked immunosorbent assay which provides a rapid and convenient means of detecting and serotyping the various strains encountered.
Herbaceous plant
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Citrus tristeza virus
Protoplast
Brome mosaic virus
Closterovirus
clone (Java method)
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Superinfection exclusion or homologous interference, a phenomenon in which a primary viral infection prevents a secondary infection with the same or closely related virus, has been observed commonly for viruses in various systems, including viruses of bacteria, plants, and animals. With plant viruses, homologous interference initially was used as a test of virus relatedness to define whether two virus isolates were "strains" of the same virus or represented different viruses, and subsequently purposeful infection with a mild isolate was implemented as a protective measure against isolates of the virus causing severe disease. In this study we examined superinfection exclusion of Citrus tristeza virus (CTV), a positive-sense RNA closterovirus. Thirteen naturally occurring isolates of CTV representing five different virus strains and a set of isolates originated from virus constructs engineered based on an infectious cDNA clone of T36 isolate of CTV, including hybrids containing sequences from different isolates, were examined for their ability to prevent superinfection by another isolate of the virus. We show that superinfection exclusion occurred only between isolates of the same strain and not between isolates of different strains. When isolates of the same strain were used for sequential plant inoculation, the primary infection provided complete exclusion of the challenge isolate, whereas isolates from heterologous strains appeared to have no effect on replication, movement or systemic infection by the challenge virus. Surprisingly, substitution of extended cognate sequences from isolates of the T68 or T30 strains into T36 did not confer the ability of resulting hybrid viruses to exclude superinfection by those donor strains. Overall, these results do not appear to be explained by mechanisms proposed previously for other viruses. Moreover, these observations bring an understanding of some previously unexplained fundamental features of CTV biology and, most importantly, build a foundation for the strategy of selecting mild isolates that would efficiently exclude severe virus isolates as a practical means to control CTV diseases.
Superinfection
Closterovirus
Citrus tristeza virus
Viral Interference
Heterologous
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The movement of four plant viruses into the hemocoel of chrysomelid and coccinellid beetle vectors after ingestion was studied. None of the four plant viruses (two beetle-transmissible and two non-beetle-transmissible) were detected in the hemolymph of the Mexican bean beetle (Epilachna varivestis), an efficient plant virus vector in the family Coccinellidae, regardless of the acquisition source, type of virus, or method of virus detection. The infectivity of viruses was not destroyed by the hemolymph of the Mexican bean beetle, as demonstrated by virus survival in hemolymph for up to 3 days after virus injection into the hemocoel (...)
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This thesis is a tentative research on the flora geography of the Raphiolepsis in our country. There are altogether fifteen species of Raphiolepsis on earth, China has seven and three varieties, which constitute 46.67% of the tatal, mainly in south China, west China, central China and southwest China. Judging by its distribution, south China is rich in species and the distinguishing features there are conspicuous. It^s the distribution center of the while country.
Flora
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Tiger
Subspecies
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Geminiviridae
Whitefly
Virus classification
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There have been few studies on the talents with geographical background.Based on the statistical da-ta,this article examines Chinese contemporary geographical professors and researchers in several aspects,in-cluding the number,age structure,native place,geographical distribution and regional differentiation,and re-veals the reasons for regional differences and relevant influencing factors.The results show that there is greater regional differentiation in eastern China than in western China,and also greater in southern China than in north-ern China.A large number of geographical brains are concentrated in Shaanxi,Guangdong,Zhejiang and Jiang-su provinces,while fewer professors and researchers are distributed in northwestern China.The regional differ-ences,to a certain extent,have been formed due to the intrinsic factors of geographical scholars,while they are affected by some factors such as economic condition,politics,and culture.
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This paper repors the investigation result of the activities of a group of South China tigers( Panthera tigris amoyensis ) appearing in Qizimei Mountains Nature Reserve in Hubei province in recent years and it then proposes some conservation and management suggestion about the tigers.
Tiger
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The HSV-1 latency-associated transcript (LAT) locus contains two small noncoding RNA (sncRNA) sequences (sncRNA1 and sncRNA2) that are not microRNAs (miRNAs). We recently reported that sncRNA1 is more important for in vitro activation of the herpesvirus entry mediator than sncRNA2, but its in vivo function is not known. To determine the role, if any, of sncRNA1 during herpes simplex virus 1 (HSV-1) infection in vivo, we deleted the 62-bp sncRNA1 sequence in HSV-1 strain McKrae using dLAT2903 (LAT-minus) virus, creating ΔsncRNA1 recombinant virus. Deletion of the sncRNA1 in ΔsncRNA1 virus was confirmed by complete sequencing of ΔsncRNA1 virus and its parental virus (i.e., McKrae). Replication of ΔsncRNA1 virus in tissue culture or in the eyes of infected mice was similar to that of HSV-1 strain McKrae and dLAT2903 viruses. However, the absence of sncRNA1 significantly reduced the levels of ICP0, ICP4, and gB but not LAT transcripts in infected rabbit skin cells in vitro. In contrast, the absence of sncRNA1 did reduce LAT expression in trigeminal ganglia (TG), but not in corneas, by day 5 postinfection (p.i.) in infected mice. Levels of eye disease in mice infected with ΔsncRNA1 or McKrae virus were similar, and despite reduced LAT levels in TG during acute ΔsncRNA1 infection, McKrae and ΔsncRNA1 viruses did not affect latency or reactivation on day 28 p.i. However, mice infected with ΔsncRNA1 virus were more susceptible to ocular infection than their wild-type (WT) counterparts. Expression of host immune response genes in corneas and TG of infected mice during primary infection showed reduced expression of beta interferon (IFNβ) and IFNγ and altered activation of key innate immune pathways, such as the JAK-STAT pathway in ΔsncRNA1 virus compared with parental WT virus. Our results reveal novel functions for sncRNA1 in upregulating the host immune response and suggest that sncRNA1 has a protective role during primary ocular HSV-1 infection. IMPORTANCE HSV-1 latency-associated transcript (LAT) plays a major role in establishing latency and reactivation; however, the mechanism by which LAT controls these processes is largely unknown. In this study, we sought to establish the role of the small noncoding RNA1 (sncRNA1) encoded within LAT during HSV-1 ocular infection. Our results suggest that sncRNA1 has a protective role during acute ocular infection by modulating the innate immune response to infection.
Virus latency
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