Koi herpesvirus and carp edema virus threaten common carp aquaculture in Croatia

Common carp (Cyprinus carpio) is a very important fish species for warm-water aquaculture in Croatia. All Croatian carp farms are subjected to a surveillance programme for the presence of koi herpesvirus (KHV), causing a deadly disease called koi herpesvirus disease (KHVD). However, there is no surveillance for other viral pathogens of importance like carp edema virus (CEV), a causative agent of koi sleepy disease (KSD). During regular testing within the KHVD surveillance programme, we tested samples for CEV simultaneously. The screening indicated possible outbreaks of KHVD and KSD. During 2016, KHVD broke out in an isolated area and soon thereafter a KHV eradication programme was successfully performed. However, during 2018 and 2019, two additional mortality events occurred in lakes in the southern part of Croatia during the spring. Samples from both events tested positive for CEV. An epidemiological investigation confirmed the introduction of infected carps from an infected farm to one of the lakes. To prevent the spreading of CEV into open waters, it is of utmost importance to introduce CEV testing before fish movement or to perform regular testing of all carp farms in the country to determine CEV prevalence for the purpose of implementation of control measures.     

Bluetongue Virus （BTV） Serological Survey and Evidence of Emergent BTV-8 Serotype in Morocco

Bluetongue （BT） is an infectious, non-contagious arthropod-borne disease that infects all ruminants, including sheep, cattle, deer, goats and camelids. Bluetongue virus （BTV） belonged to Reoviridae is ARN genome of 19 Kb. Twenty-six BTV serotypes have long been recognized, to be associated with severe disease in certain breeds of sheep, whereas cattle and goats are usually sub-clinically affected. Before 2004, BT was considered an exotic disease in Morocco, however, the first outbreak was observed in 2004 in sheep. This outbreak was caused by the isolated BTV-4. Two years later a BTV-1 emerged in Morocco. Both serotype 1 and serotype 4 circulated after 2007 across the country. The aims of the present work was to perform a serological study on sheep from different regions in Morocco in order to clarify the current BTV epidemiological situation and its evolution from 2009 to 2012, to determine the co-infection rate, and to confirm the possible circulation of other BTV Serotype mainly the BTV-8. All of 436 sera were tested by serum neutralization using reference strains. Results confirm the presence of BTV-4, BTV-1 and BTV-8. However, the present study report for the first time the emerging BTV-8 circulation in Morocco. Moreover, the founding reveal as well a higher co-infection rate in cattle compared to sheep.     

广东省猪圆环病毒2型感染的血清学调查

为了解广东省猪群中猪圆环病毒2型(PCV-2)的感染情况,应用酶联免疫吸附试验(ELISA)对广东部分地区的764份不同年龄段的猪血清进行PCV-2抗体检测,对PCV-2与猪猪繁殖与呼吸综合征病毒(PRRSV)、伪狂犬病病毒(PRV)混合感染情况做了进一步调查.结果表明,PCV-2抗体检测平均阳性率为61.91％(47...     

肉鸡及其鸡胚中CAV和ALV的PCR检测

应用PCR技术对山东省3个中小型AA肉种鸡场的鸡胚、1日龄雏鸡和子代肉鸡CAV和ALV的感染情况进行了检测。用相同的方法直接采集样品的不同组织提取2种病毒DNA,进行PCR扩增及PCR产物的克隆和序列测定。结果表明:被检的3个肉种鸡场均有这2种病毒的感染,其中CAV的阳性率24.22%,ALV的阳性率17.56%,二者共感染的阳性率8.89%。感染鸡各组织中病毒含量也有差异,CAV以脾脏最多,ALV以肾脏最多。对肝脏进行细菌分离培养,并对40日龄商品肉鸡进行ND血凝抑制(HI)抗体效价检测,发现大肠杆菌等细菌感染阳性率较高,ND-HI抗体效价显著偏低。说明该地区肉种鸡场和商品鸡场均存在严重的CAV和ALV感染以及与细菌性疾病的共感染,并导致鸡只的机体免疫力下降。     

Pre-exposure to infectious hypodermal and haematopoietic necrosis virus or to inactivated white spot syndrome virus (WSSV) confers protection against WSSV in Penaeus vannamei (Boone) post-larvae

Larvae and post-larvae of Penaeus vannamei (Boone) were submitted to primary challenge with infectious hypodermal and haematopoietic necrosis virus (IHHNV) or formalin-inactivated white spot syndrome virus (WSSV). Survival rate and viral load were evaluated after secondary per os challenge with WSSV at post-larval stage 45 (PL45). Only shrimp treated with inactivated WSSV at PL35 or with IHHNV infection at nauplius 5, zoea 1 and PL22 were alive (4.7% and 4%, respectively) at 10 days post-infection (p.i.). Moreover, at 9 days p.i. there was 100% mortality in all remaining treatments, while there was 94% mortality in shrimp treated with inactivated WSSV at PL35 and 95% mortality in shrimp previously treated with IHHNV at N5, Z1 and PL22. Based on viral genome copy quantification by real-time PCR, surviving shrimp previously challenged with IHHNV at PL22 contained the lowest load of WSSV (0-1x10(3) copies microg-1 of DNA). In addition, surviving shrimp previously exposed to inactivated WSSV at PL35 also contained few WSSV (0-2x10(3) copies microg-1 of DNA). Consequently, pre-exposure to either IHHNV or inactivated WSSV resulted in slower WSSV replication and delayed mortality. This evidence suggests a protective role of IHHNV as an interfering virus, while protection obtained by inactivated WSSV might result from non-specific antiviral immune response.     

蛋鸡中发现J亚群白血病与网状内皮增生症自然混合感染

发病蛋鸡经组织学、免疫组化检测确诊为J亚群白血病与网状内皮增生症混合感染。与人工接种病例不同的是，在肿瘤组织内还发现一种特殊的细胞——淋巴-巨噬细胞；在骨髓和肿瘤组织中检测到部分髓细胞胞浆内有ALV—J抗原表达。从发病情况、各器官病变程度及免疫组化结果来看，2种病原存在明显的相互协同作用，脾可能是网状内皮增生症的原发器官。但其发病的时间可能不如J亚群白血病早。此次在蛋种鸡发现此混合感染提示，病毒在环境选择压及免疫选择压的作用下，其生物特性、致病作用以及宿主范围均可发生改变。应警惕J亚群白血病和网状内皮增生症混合感染在蛋鸡中的大面积暴发。     

禽网状内皮组织增生病病毒和马立克氏病病毒共感染对鸡的致肿瘤作用

用禽网状内皮组织增生病病毒(REV)和马立克氏病病毒(MDV)共感染肉鸡，研究这2种病毒对鸡的致瘤作用，结果表明肉鸡共感染MDV和REV后13d即可发生死亡．接种后100d死亡率达84％。死亡鸡的肝脏、脾脏、肾脏和心脏等可以形成2种外观明显不同的散在的大肿瘤结节和弥漫性的小肿瘤结节。取发病鸡的肝脏、脾脏、肾脏、心脏和腺胃等组织样品做连续石蜡切片，HE染色后发现这些脏器均存在2种不同类型的肿瘤细胞增生。对这些连续切片分别用MDV和REV的单克隆抗体进行间接荧光试验，则同1份样品存在可以与REV和MDV分别呈现阳性反应的肿瘤细胞团，结果表明REV和MDV可以在感染鸡的体内分别诱发形成肿瘤。在接种后14、21、28和42d随机采集3只鸡的全血分离MDV和REV，均可以同时分离到MDV和REV。表明REV和MDV的共感染延长了病毒血症的时间。     

番茄褪绿病毒与番茄黄化曲叶病毒复合侵染对番茄褪绿病毒传播的影响

番茄褪绿病毒Tomato chlorosis virus(ToCV)是一种由烟粉虱Bemisia tabaci传播的正义单链RNA病毒,在田间常与番茄黄化曲叶病毒Tomato yellow leaf curl virus(TYLCV)复合侵染而造成番茄生产上重大的经济损失。为了明确ToCV与TYLCV的复合侵染对烟粉虱传播ToCV所造成的影响,本文采用RT-PCR以及qRT-PCR检测了复合侵染的番茄对烟粉虱获取和传播ToCV的影响。研究表明,烟粉虱取食复合侵染的番茄后对ToCV的传播效率显著提高,仅25头烟粉虱的传毒率即可达到100%,ToCV在烟粉虱以及番茄体内的累积量均显著提高。说明这种复合侵染促进了烟粉虱对ToCV的传播,在田间应当及时防控烟粉虱,警惕病毒与烟粉虱的蔓延。     

应用dsRNA测序技术检测草鱼呼肠孤病毒的混合感染

从草鱼(Ctenopharyngodon idellus)出血病疑似病料提取物感染的草鱼肾细胞(CIK)中提取病毒基因组dsRNA,电泳显示出水生呼肠孤病毒基因组的典型特征。应用简化的FLAC(full-length amplification of cDNA)技术扩增得到病毒的4个全长基因组片段进行测序分析。核酸序列BLAST分析表明:其中3个基因组片段与GCRV-873第5、9、10片段高度同源,另外1个基因组片段与GCRV-HZ08第11片段高度同源;因此推测病料中同时存在两种不同的病毒核酸,但也可能存在一种杂合病毒。根据已发表的GCRV-HZ08第5、9、10片段设计了3对引物对分离的病毒总RNA进行RT-PCR检测并测序,结果显示这3个片段与GCRV-HZ08第5、9、10片段均具有99%同源性,表明是由于混合感染而存在两株不同病毒的核酸dsRNA,两株病毒分别命名为GCRV-JX01和GCRV-JX02。首次运用dsRNA测序法检测出了GCRV病毒的混合感染,为草鱼呼肠孤病毒的流行病学和防控提供了一种新的技术选择。     

禽波氏杆菌与REV共感染对SPF鸡免疫系统的影响

本研究用禽波氏杆菌(Bordetella avium,B.avium)和禽网状内皮增生症病毒(reticuloendotheliosis virus,REV)人工感染SPF鸡胚和SPF雏鸡后,测定鸡胚死亡率和孵化率,检测SPF雏鸡的免疫器官指数、淋巴细胞比率和淋巴细胞转化率(LTR),探究REV和B.avium共感染对SPF鸡免疫系统的影响.结果显示,二者同时感染时鸡胚的孵化率只有27.85％,且SPF雏鸡的免疫器官指数和淋巴细胞转化率(LTR)显著低于正常对照组.因此,B.avium和REV共感染可造成SPF鸡胚孵化率大幅降低、1日龄SPF雏鸡免疫系统严重损伤及免疫功能低下.