A Systems-Based Approach to Safeguard the Strawberry Industry from Virus Diseases

ABSTRACT

Strawberry is susceptible to several systemic pathogens and, in particular, viruses. There are several examples of disease epidemics that resulted from virus-infected propagation material and led to losses estimated in the tens of millions of dollars. This communication focuses on actions needed to minimize the risk of similar outbreaks by developing a systems-based approach from breeding to the commercial field. This includes the development of molecular biology and bioinformatic tools that allow for the detection of all known viruses infecting strawberry but most importantly for the discovery of viruses that circulate in the system undetected and may have contributed to past epidemics. Surveys in commercial fields have yielded a map of the most prevalent viruses in strawberry production areas across the United States, knowledge that will be used in the nascent National Certification Program for Strawberry.     

An epizootic of bovine ephemeral fever in New South Wales in 2008 associated with long-distance dispersal of vectors

Objective To report the rapid transmission of bovine ephemeral fever ( BEF) virus from north-western New South Wales south to the Victorian border in January 2008 and to present data that suggests an uncommon meteorological event caused this rapid southward dispersal of vectors. Procedure The locations of reported clinical cases, data from sentinel herds and results from a survey of cattle in the southern affected area were examined to delineate the distribution of virus transmission. Synoptic weather charts for January 2008 were examined for meteorological conditions that may have favoured movement of vectors in a southerly direction. Results Cases of BEF and exposure to BEF virus in NSW were confirmed west of the Great Dividing Range, extending from the Queensland border to Finley, on the far North Coast and around the Hunter Valley. A low-pressure system moved south across the state on 18–19 January 2008, preceding the first cases of BEF in the south of NSW by 1–2 days. Conclusion Heavy rainfall in December 2007 provided a suitable environment for vector breeding, resulting in the initiation of and support for continuing BEF virus transmission in north-western NSW. The movement of a low-pressure system south across central western NSW in mid-January 2008 after the commencement of BEF virus transmission in the north-west of the state provided a vehicle for rapid southward movement of infected vectors.     

小反刍兽疫病毒核衣壳蛋白抗原性与特异性的比较

为筛选建立小反刍兽疫病毒N蛋白双抗原夹心ELISA抗体检测方法的抗原原料,本研究通过优化大肠杆菌密码子、优化蛋白表达与纯化条件等方法,分别在pET-30a与pET-32a两个不同原核表达载体中成功获得了可溶性的小反刍兽疫核衣壳蛋白(N)。分别对重组大肠埃希氏菌pET-30a-(N)-BL21(DE3)株与pET-32a-(N)-BL21(DE3)株种子批的P7代与P20代进行蛋白诱导表达与抗原提取纯化,共获得6批小反刍兽疫病毒pET-30a-(N)蛋白与pET-32a-(N)蛋白,并对蛋白的浓度、纯度、抗原性和特异性进行检验。结果表明两个纯化后的重组抗原与羊小反刍兽疫病毒阳性血清有明显反应,具有较好的反应性,而与羊痘病毒阳性血清、羊口蹄疫病毒阳性血清、山羊关节炎/脑炎病毒阳性血清等特异性血清均无交叉反应,具有较好的特异性。本研究结果为今后以N蛋白为基础建立相应的抗原捕获ELISA方法,竞争ELISA检测方法、间接ELISA检测方法以及双抗原夹心ELISA抗体检测方法打下了坚实的基础。     

Perspectives on cocoa swollen shoot virus disease (CSSVD) management in Ghana

The cocoa swollen shoot virus disease (CSSVD) caused by the Cacao swollen shoot virus (CSSV) has for many years been a major constraint to cocoa (Theobroma cacao) production in West Africa. The virus (CSSV) is a member of the Badnavirus (bacilliform DNA virus) genus and is semi-persistently transmitted through the feeding action of several mealybug species (Pseudococcidae, Homoptera). Its severest types could substantially reduce yield by about 70% and even cause death of cocoa trees within 2–3 years of infection at all stages of cocoa growth. Although the virus was first identified in the Eastern region of Ghana, it is now very devastating in the Western region where the bulk of Ghana's cocoa is produced and has also been reported in other West African cocoa producing nations such as Cote D'Ivoire, Togo and Nigeria. Over the years, the disease has been managed in Ghana using the “cutting out method” with the aim to remove scatter infections serving as sources of inoculum to help limit spread to only outbreak areas and also replant farms with tolerant cocoa hybrids as well as controlling the vectors. However, some of these control methods has encountered many challenges leading to opposition from farmers and intermittent stoppages. The high prevalence of the virus has been attributed to failure to adequately eliminate scatter infections and also control the vectors. The need to discuss some of the challenges affecting the management of the disease and the resultant high occurrence of the virus across the cocoa regions is considered very important. This paper therefore puts into perspectives some of the challenges associated with CSSVD management and discusses reasons for the increased spread of the disease. The paper concludes with recommendations to support integrated management of the virus and vectors to sustain cocoa production in West Africa.     

杏树良种引种试验研究

采用多元统计分析方法对杏树良种引种试验结果进行了分析．首先用二元对比排序方法，确定了果形、色泽、大小、肉质、汁液、风味、杏仁的权重向量，从果形、色泽、大小等７方面对品质进行了评判，结果表明，唐汪川桃杏品质最优，兰州大接杏次之；然后利用相对欧氏距离计算了品质、抗寒性、丰产性的模糊优先比．表现优劣的顺序为：兰州大接杏＞安宁１８号＞华县大接杏＞唐汪川桃杏＞梅杏＞金妈妈＞猪皮水杏＞大偏头杏＞曹杏．     

慢病毒介导的RNAi靶向NDVP基因抑制其在CEF上的复制

通过研究慢病毒介导的RNA干扰靶向新城疫病毒P基因抑制其在鸡胚成纤维细胞上的复制,从而为新城疫病毒的抗病毒研究奠定基础。①针对NDVP基因设计siRNA干扰序列,构建慢病毒（lentivirus）介导的RNAi重组载体;②携带有siRNA表达元件重组慢病毒包装及其滴度测定;③包装后重组慢病毒接种CEF细胞并接毒NDV,48h分别进行Realtime RT-PCR和NDV滴度测定,并观察细胞病变情况。结果表明,本研究针对NDVNA-1株P基因2个RNAi靶位（位于开放阅读框的641和827位）设计的RNAi641和RNAi-827,对病毒复制具很强的抑制效果,且641位的重要性大于827位．     

A survey on canine leishmaniasis and phlebotomine sand flies in central Italy

Zoonotic visceral leishmaniasis (ZVL) is a vector-transmitted zoonosis caused by the parasitic protozoan Leishmania infantum. Bloodsucking sand flies of the subfamily Phlebotominae are the obligatory insect hosts, and the dog is the only domestic reservoir.This study reports data from a survey of canine infection and sand fly phlebotomine monitoring in the province of Perugia in central Italy. The overall seroprevalence in a total of 100 dogs tested was 8% (95% confidence interval: 3.8-15.6%). Data analysis revealed that serological positivity was statistically associated with age (p-value = 0.03) and the area where dogs lived. Standard blacklight traps employed for sampling Culicoides midges in bluetongue disease surveillance were used in phlebotomine monitoring. A total of 5698 sand flies were collected and the two species, Leishmania competent vectors, were identified, Phlebotomus perfiliewi (50%) and Phlebotomus perniciosus (30%).     

Ecological correlates of bluetongue virus in Spain: predicted spatial occurrence and its relationship with the observed abundance of the potential Culicoides spp. vector

Using data from bluetongue (BT) outbreaks caused by viral serotype 4 (BTV-4) in Spain during 2004–2005, a predictive model for BTV-4 occurrence in peninsular Spain was developed. An autologistic regression model was employed to estimate the relationships between BTV-4 presence and bioclimatic-related and host-availability-related variables. In addition, the observed abundances of the main potential Culicoides vectors during 2004–2005, namely Culicoides imicola, Culicoides obsoletus group, and species of the Culicoides pulicaris group, were compared between BTV-4 presence/absence areas predicted by the model.BTV-4 occurrence was mainly explained by bioclimatic variables, although a consideration of host-availability variables led to improved fit of the model. The area of BTV-4 presence predicted by the model largely resembled the core distribution area of C. imicola, and this species was the most abundant Culicoides spp. in predicted BTV-4 presence areas. The results suggest that the spatial expansion of BTV-4 took place only as far as those areas in which C. imicola populations efficiently transmitted the virus.