Evidence for plant viruses in the region of Argentina Islands, Antarctica

This work focused on the assessment of plant virus occurrence among primitive and higher plants in the Antarctic region. Sampling occurred during two seasons (2004/5 and 2005/6) at the Ukrainian Antarctic Station 'Academician Vernadskiy' positioned on Argentina Islands. Collected plant samples of four moss genera (Polytrichum, Plagiatecium, Sanionia and Barbilophozia) and one higher monocot plant species, Deschampsia antarctica, were further subjected to enzyme-linked immunosorbent assay to test for the presence of common plant viruses. Surprisingly, samples of Barbilophozia and Polytrichum mosses were found to contain antigens of viruses from the genus Tobamovirus, Tobacco mosaic virus and Cucumber green mottle mosaic virus, which normally parasitize angiosperms. By contrast, samples of the monocot Deschampsia antarctica were positive for viruses typically infecting dicots: Cucumber green mottle mosaic virus, Cucumber mosaic virus and Tomato spotted wilt virus. Serological data for Deschampsia antarctica were supported in part by transmission electron microscopy observations and bioassay results. The results demonstrate comparatively high diversity of plant viruses detected in Antarctica; the results also raise questions of virus specificity and host susceptibility, as the detected viruses normally infect dicotyledonous plants. However, the means of plant virus emergence in the region remain elusive and are discussed.     

Regeneration of midgut epithelial cell in the silkworm, Bombyx mori, infected with viruses

In the larvae of the silkworm, Bombyx mori, the regeneration of midgut cells infected with a cytoplasmic polyhedrosis virus (CPV), a flacherie virus (FV), and a small DNA virus (SDV) was studied. Large numbers of newly developed cells appeared in the CPV-infected part of the midgut epithelium just before larval molt, and along with their development, the CPV-infected old columnar cells were discharged into the midgut lumen during the molt. On the other hand, in the uninfected portion of the midgut only a few cells developed, and no columnar cells were discharged. Similarly, the marked replacement of midgut epithelial cells during larval molt was also observed in larvae infected with CPV + FV. In the larvae infected with CPV + SDV, the columnar cells lost their regenerative ability, and because of the exfoliation of infected columnar cells, the midgut epithelium consisted mainly of uninfected goblet cells at a late stage of infection. The degree of epithelial regeneration varied with the silkworm strain and the dosage of the virus.     

The susceptibility of the pea moth, Cydia nigricana, to infection by the granulosis virus of the codling moth, Cydia pomonella

Laboratory studies demonstrated that neonate larvae of the pea moth, Cydia nigricana, are susceptible to infection with a granulosis virus (CpGV) isolated from the codling moth, Cydia pomonella. Comparative LC₅₀ values for C. nigricana and C. pomonella are 1.90 × 10⁵ and 1.54 × 10⁴ capsules/ml of diet, respectively. The virus extracted from CpGV-infected pea moth larvae is serologically related, and probably identical, to CpGV.     

2006年广州登革热病原体的分离鉴定及其生物学性质的观察

目的：对2006年广州流行登革热病原进行分离鉴定及生物学性质研究。方法：采用传代蚊细胞微量培养方法对2006年广州登革热病原进行分离,并通过脑内途径观察其对乳鼠的致病性;经间接免疫荧光和RT-PCR技术,对患者血清标本中的病毒特异抗体及新分离的病原体进行检测和鉴定;将此次分离的病原体与1980年分离的同型毒株进行生物学性质比较。结果：从57份患者血清标本中分离出10株病毒,在传代蚊细胞中可产生稳定的细胞病变并对乳鼠致病;其基因组为登革1型病毒特异的RNA分子,经鉴定为登革1型病毒;此次分离的登革1型病毒与1980年分离的同型毒株在致细胞产生病变的时间和严重程度,蚀斑的大小、形态以及致乳鼠发病的时间等生物学性质上有所不同。结论：2006年广州流行登革热病原为登革1型病毒,且与1980年分离的同型毒株在生物学性质方面存在明显差异。     

中国首次分离的辛德毕斯病毒XJ-160病毒株感染性全基因组cDNA克隆的构建与分析

报告了中国首次分离的辛德毕斯病毒XJ-160株的感染性全基因组cDNA克隆的构建与鉴定。利用RT—PCR方法获得覆盖病毒全长基因组的cDNA片段,以低拷贝质粒pBR322作为骨架,将基因组cDNA置于SP6RNA聚合酶启动子之后,基因组3’末端带有35个连续的A,通过DNA重组技术组装成病毒基因组全长cDNA克隆。该克隆可在大肠杆菌DH5a中稳定扩增。经体外转录,RNA转录体转染BHK-21细胞,细胞发生病变,恢复病毒滴度达到10^7～10^8PFU／ml。全基因组cDNA克隆构建过程中引入的沉默突变(8453位核苷酸由C变为T)产生XbaⅠ酶切位点作为遗传标记,在子代恢复病毒的基因组中稳定存在。从细胞病变的特征、BHK-21细胞的空斑形态、病毒的抗原性、病毒在细胞中的生长动力学特征以及对乳鼠的致病性等方面比较,恢复病毒和亲本病毒XJ-160没有显著区别,提示获得了具有感染性的XJ-160病毒全长cDNA克隆。该病毒感染性全基因组cDNA克隆可以作为反向遗传学系统,为进一步研究病毒复制和致病机制,以及开发相应的载体表达系统提供分子生物学工具。     

Detection,distribution and control of Potato mop-top virus,a soil-borne virus,in northern Europe

Potato mop-top virus (PMTV; genus Pomovirus; family Virgaviridae) is transmitted by the soil-borne Spongospora subterranea f.sp. subterranea, a protoctist that causes powdery scab on potato. PMTV is distributed widely in the potato growing areas in South and North America, Japan and northwestern Europe. This article reviews the current knowledge on detection, distribution and control of PMTV with focus on the Baltic Sea region. Since the 1980s, PMTV has caused great economic losses to potato production in the Nordic countries (Norway, Sweden, Denmark and Finland), but its occurrence in other countries of the Baltic Sea region remained unknown. To fill this knowledge gap, harmonised sampling and virus detection procedures including bioassays and serological and molecular methods were employed by 21 research institutions to detect PMTV in potato tubers and soil samples in 2005–2008. Potato growing areas were widely contaminated with PMTV in the Nordic countries. Only the main seed potato production area in northern Sweden and the High Grade seed potato production zone in Finland were negative for PMTV. Intensive and systematic surveys in Poland in 2004–2008 found no evidence of PMTV, except a single PMTV-infected tuber detected in 2008. Surveys in the Baltic countries (Lithuania, Latvia and Estonia) and northwestern Russia (Leningrad province) were negative for PMTV, except infection of minitubers in a screenhouse in Latvia in 2005. Varying percentages of tubers expressing spraing symptoms in Sweden, Norway, Denmark and Poland were infected with Tobacco rattle virus, and bioassays indicated similar results for Russia. Incidence of symptomless infections with PMTV was high in tubers of many potato cultivars. Here, we discuss the contrasting patterns of distribution of PMTV in the Baltic Sea region, factors playing a role in dispersal and establishment of PMTV in new fields and means for controlling PMTV and its spread to new areas. We emphasise the use of the current virus-specific methods for the detection of PMTV in symptomless potato tubers and the high risks of disseminating PMTV to new fields and areas in viruliferous resting spores of S. subterranea in the soil adhering to seed tubers. PMTV-resistant potato cultivars will provide the only sustainable means for preventing yield losses in the infested fields and the prospects of resistance breeding are summarised.     

Control of aphid-vectored and thrips-borne virus spread in lily, tulip, iris and dahlia by sprays of mineral oil, polydimethylsiloxane and pyrethroid insecticide in the field

In this study control of spread by insect vectors of non‐persistent Lily symptomless virus and Lily mottle virus in lily, Tulip breaking virus in tulip, Iris mild mosaic virus, Narcissus latent virus and Iris severe mosaic virus in bulbous iris, and semi‐persistent Dahlia mosaic virus and persistent Tomato spotted wilt virus in dahlia has been evaluated with weekly sprays of mineral oil, beta‐pinene emulsion, polydimethylsiloxane emulsions and pyrethroid insecticide. In lily, beta‐pinene in ‘Wilt Prufgave’ 40% reduction of virus spread. In 1995–97 deltamethrin in ‘Decisgave’ 22–58% reduction. Deltamethrin added to sprays of mineral oil ‘Luxan oil H’ and polydimethylsiloxane (PDMS), e.g. in ‘Dow Corning 36’, efficiently improved control efficacy. The latter was also observed in tulip and dahlia. Mineral oil and deltamethrin gave best control by 81–97% reduction of virus spread at standard spray volumes (6.25 litre ha^?1+0.4 litre ha¹). ‘Luxan oil H’ at 3.125 litre ha^?1 with deltamethrin gave 69–91% control. Efficacy of control by polydimethylsiloxane in ‘Dow Corning 36’ was superior to ‘Luxan anti‐foam’. ‘Dow Corning 36’ with deltamethrin (7+0.4 litre ha^?1) gave satisfactory control (68–87%). In tulip, the control by ‘Dow Corning 36’/deltamethrin sprays proved satisfactory compared with ‘Luxan oil H’/‘Decis’‐sprays. In bulbous iris the efficacy of tested PDMS‐brands was clearly different in favour of ‘Dow Corning 36’. In dahlia mineral‐oil and PDMS‐sprays gave some control of semi‐persistent DaMV (16–24%). This ranged at higher level (65–80%) when deltamethrin was added to the spray mixture. Similar trends were observed in the control of persistent TSWV. The effect of polydimethylsiloxane emulsions in the spectrum of virus‐control agents is described for the first time. The effect of PDMS compared with that of mineral oils and synthetic pyrethroid insecticides is discussed with respect to efficacy, mode of action to prevent virus transmission and possible reduction of bulb weights in vegetatively propagated bulb crops.     

Genetically determined nonsusceptibility of the silkworm,Bombyx mori,to infection with a densonucleosis virus (Densovirus)

A nonsusceptible and a highly susceptible strain of the silkworm, Bombyx mori, to peroral infection with a densonucleosis virus (DNV) were studied by probit analysis. Tests with the susceptible and nonsusceptible parent strains, their reciprocal F₁ hybrids, the F₂ hybrid, and the backcrossed hybrids to either of the parents demonstrated that the nonsusceptibility of the silkworm to DNV was inherited and controlled by a recessive gene which was not sex-linked.     

Functional differences between occluded and nonoccluded viruses of a nuclear polyhedrosis of the silkworm, Bombyx mori.

Comparative infectivity and virus neutralization studies on occluded and nonoccluded viruses of Bombyx mori nuclear polyhedrosis revealed that the infectious unit causing peroral infection differed from that causing hemocoelic infection. There were functional differences between the occluded (mainly virons with envelopes) and the nonoccluded virus (mainly virions without envelopes) preparations. The peroral infection was largely due to the virion with an envelope (peroral infectious unit), and the hemocoelic infection was due largely to the virion without an envelope (hemocoelic infectious unit). The apparent change of the virions with envelope to those without envelopes was detected as a slight increase in hemocoelic infectivity when the occluded virus was diluted and incubated at 4°C for more than 6 days.     

Comparative aspects of infectious salmon anemia virus,an orthomyxovirus of fish,to influenza viruses

Infectious salmon anaemia (ISA) is a viral disease that was first recorded in 1984 in farmed Atlantic salmon. The infectious salmon anaemia virus (ISAV) is classified as the type species of the genus Isavirus in the Orthomyxoviridae family and is evolutionary remote to the influenza viruses. The genome consists of eight negative single-stranded RNA segments, and it utilises the same mechanisms as influenza viruses to enter and exit cells. Although a common ancestor of ISAV and other genera of Orthomyxoviruses could be dated back several millions of years, there are still many similarities between ISAV and the influenza viruses regarding morphology, replication cycles and interactions with their respective hosts.     

2018-2019年云南省部分地区鼠类携带汉坦病毒基因型别分析

为了解云南省汉坦病毒的分子流行病学特征,本研究在云南省祥云县、泸西县、禄丰县和楚雄市4个地区布点,采集鼠类动物标本,运用实时荧光RT-PCR检测鼠肺标本中的汉坦病毒中的汉滩病毒和首尔病毒核酸,通过PCR扩增S节段的全基因序列,并进行核苷酸同源性分析和遗传进化分析。结果共捕获鼠类动物70份,包含10个鼠种,其中褐家鼠30只,占42.9%,其次是鼩鼱12只,占17.1%;核酸检测阳性标本19份,均为首尔病毒,检出率为27.1%,源自祥云县的标本检出率在四个地区中最高(32.0%)。从鼠肺标本中扩增得到8条汉坦病毒S节段全基因序列,相似性为87.0%~99.7%,遗传进化分析显示基因序列聚集形成2个分支,一个分支属于S1亚型,另一个分支在遗传进化分析和blast比对分析中与其他亚型同源性均小于90%,属首尔病毒中独立的新的遗传进化分支,提示了云南省鼠类动物间多基因亚型首尔汉坦病毒流行,应进一步关注由宿主动物溢出感染人的潜力。     

Survival of spumavirus,a primate retrovirus,in laboratory media and water

The persistence of a previously characterized spumavirus strain (strain SV-522) was investigated utilizing various laboratory media and waters, including Eagle's minimal essential medium (EMEM) plus 0% fetal bovine serum (EMEM-0%), EMEM-2%, EMEM-10%, Chlamydia transport medium (CTM), phosphate-buffered saline, distilled, estuarine, and marine water, human serum, and the germicides, ethyl alcohol (70%) and sodium hypochlorite (10%). Experiments were performed at 4 degrees C and/or 23 degrees C. Infectivity endpoints were determined in stock aliquots upon initiation of testing and then after 3, 5, 7, and 10 days. The virus was reisolated from all diluents after 5 days at 23 degrees C and in EMEM-10% after 7 days. The virus was detected in CTM, EMEM-2%, EMEM-10%, and estuarine and marine waters after 7 days at 4 degrees C. Differences in the persistence of the virus may be ascribed to temperature and organic load. Water ionic strengths (e.g., estuarine vs. marine water) had no effect on modifying persistence of viral particles. Infectivity of spumavirus was undetectable after 30 s in 70% ethanol or 10% sodium hypochlorite. After 30 min at 23 degrees C, spumavirus infectivity in normal but not heat-inactivated human serum increased by almost 100-fold. Persistence of infectivity of primate spumavirus after 7 days in media and waters, and the agent's infectious potential in the human host, emphasize a need for cautious recognition during the manipulation of primate cells/organs and in the handling of primates themselves.     

Inheritance of resistance to potyviruses in Phaseolus vulgaris L. IV. Inheritance, linkage relations, and environmental effects on systemic resistance to four potyviruses

We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv Great Northern 1140 (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.     

Ingestion, transmission, and persistence of Chino del tomate virus (CdTV), a New World begomovirus, by Old and New World biotypes of the whitefly vector Bemisia tabaci

Two whitefly biotypes of Bemisia tabaci, from either the Eastern or Western Hemisphere, respectively, were compared with respect to their competency to ingest and their efficiency to transmit the New World begomovirus, Chino del tomate virus (CdTV). The AZ A biotype of B.tabaci originates from the arid southwestern USA and northwestern Mexico, while the B biotype has an origin in the Middle East or Northern Africa. The ability of these two vector biotypes to ingest and subsequently to transmit CdTV were evaluated for an acquisition‐access period (AAP) that ranged from 0 to 72 h, followed by a 48 h inoculation‐access period (IAP). Individual adult whiteflies were monitored for CdTV ingestion using polymerase chain reaction (PCR) to detect the viral coat protein gene (AV1 ORF), and transmission efficiency (frequency) was determined by allowing potentially viruliferous whiteflies access to tomato seedlings following each experimental AAP. PCR results for individual adult whiteflies indicated that CdTV was ingested from infected tomato plants by both biotypes 93% of the time. Transmission frequencies by both vector biotypes increased with longer AAPs. However, the AZ A biotype transmitted CdTV 50% of the time, compared to only 27% for the B biotype. Evidence that virus was ingested with equal competency by the A and B biotypes confirmed that both vectors were capable of ingesting CdTV from tomato at the same frequency, even when the AAP was 0.5 h. Consequently, either the acquisition and/or transmission stages of the pathway, rather than ingestion competency, were responsible for differences in vector‐mediated transmissibility. Detection frequency of CdTV, after 48 h AAP, by PCR in single females of AZ B biotype was significantly higher than males.     

The effect of Pymetrozine, a feeding inhibitor of Homoptera, in preventing transmission of cauliflower mosaic caulimovirus by the aphid species Myzus persicae (Sulzer)

Mature turnip plants, mechanically infected as seedlings with the semi-persistent, aphid transmitted caulimovirus, cauliflower mosaic (CaMV), were treated by spraying with either a solution of Pymetrozine plus adjuvant oil, adjuvant oil or water only. At the same time turnip seedlings were sprayed for each of the three treatments. Two h after spraying, Myzus persicae were caged onto an infected turnip plant for each of the three treatments. Twenty four h later, groups of 20 aphids were transferred from the infected plants, to seedlings from each of the three treatments. After 24 h, these were removed and seedlings were later recorded for infection. This acquisition/transmission assay was repeated at 3, 7, 14 and 21 days from treatment. Only aphids exposed to the Pymetrozine treated source plants were shown to move off the plant and failed to transmit CaMV effectively to treated or control seedlings during the 0 and 3 day assays. The majority soon died when transferred to test seedlings. Progressively, more aphids were found to survive and transmit CaMV during the 7 day and 14 day assays. By 21 days no significant effect could be recorded between treatments and controls. Aphids transferred from control treated source plants to Pymetrozine treated seedlings were able to transmit CaMV within all the assays, although higher mortality was recorded in the day 0 assessment when compared to those transferred to control treated seedlings. We conclude from this trial, that a single foliar treatment of 100 mg litre¹ Pymetrozine to CaMV infected turnip plants, effectively reduces the vectoring capability of M. persicae, that feed on these plants, for up to 7 days. However, Pymetrozine failed to stop virus transmission to treated seedlings from the ingress of viruliferous aphids. Pymetrozine was not shown to cause any phytotoxic responses to plants used in this trial.     

Taura syndrome,a disease important to shrimp farms in the Americas

World Journal of Microbiology and Biotechnology -     

A damaging outbreak of arabis mosaic nepovirus in blackcurrant, the occurrence of other nepoviruses in Ribes species, and the demonstration that alfalfa mosaic virus is the cause of interveinal white mosaic in blackcurrant

In a crop of blackcurrant (Ribes nigrum), cv. Baldwin in Eire, chlorotic mottling and ringspot symptoms in leaves on plants and severe crop loss was associated with infection with arabis mosaic nepovirus (ArMV) and the presence in the soil of its nematode vector, Xiphinema diversicaudatum. This is only the second report of ArMV damaging a crop of blackcurrant. Tomato black ring (TBRV) and raspberry ringspot nepoviruses were detected in single plants of redcurrant (R. rubrum) in England and flowering currant (R. sanguineum) in Scotland respectively; each of these infected plants showed foliar chlorotic line-pattern symptoms. This is the first record of TBRV in redcurrant. A single blackcurrant plant in New Zealand showing symptoms typical of those described for interveinal white mosaic disease, contained alfalfa mosaic virus (AMV). When AMV particles were purified and concentrated from herbaceous test plants and mechanically inoculated to young blackcurrant plants, several became infected with AMV and most infected plants developed systemic symptoms typical of the original disease. This provides the strongest evidence to date that AMV is the causal agent of interveinal white mosaic disease.