Maternal antibodies against equine influenza virus in foals and their interference with vaccination.

Foals that were born to mares vaccinated twice a year against influenza had moderate to high haemagglutination-inhibition antibody titers at 24 hours after birth. The foals were vaccinated at six and ten weeks of age, and again at three to five months after birth. Four months after the third vaccination no antibodies against A/H7N7 and A/H3N8 influenza viruses were detected in these foals. Thus, maternal antibodies probably prevented the development of antibodies against equine influenza virus after vaccination. Foals born to the same mares one year later were monitored to determine the rate of decline of maternal antibodies against influenza viruses. Antibody titers of the foals shortly after birth were similar to those of the mares at foaling. The antibodies persisted for three to six months, and their biological half-life was estimated to be approximately 38 days. Two vaccinations of foals against influenza after the maternal antibodies had virtually disappeared resulted in an antibody response in most, but still not all, foals. These findings suggest that foals should not be vaccinated against influenza until maternal antibodies have disappeared.     

RNA干扰抗动物病毒感染的研究进展

RNA干扰(RNA interference,RNAi)是指在进化过程中高度保守的、由双链RNA(double stranded RNA,dsRNA)诱发的、同源mRNA高效特异性降解的现象。现已证明RNAi现象广泛     

Identification of field isolates of infectious bronchitis virus by interference with the La Sota of strain of Newcastle disease virus

The interference phenomenon of infectious bronchitis virus (IBV) with growth of Newcastle disease virus (NDV) in embryonating chicken eggs (ECE) was used as a diagnostic method. Fifteen field isolates obtained from presumptively infectious-bronchitis-affected chickens were analyzed by the IBV-NDV interference test. Eight isolates were capable of interfering with the growth of the La Sota strain of NDV, as measured by hemagglutination (HA) activity when IBV was inoculated 10 hr before NDV into ECE. The interference was considered specific for IBV, because it could be eliminated by adding homologous anti-IBV serum. The sensibility of this method could be demonstrated, because in some cases low-passage levels of IBV isolates showing HA interference ability were not capable of producing lesions in ECE. Furthermore, serologically negative IBV samples did not interfere with NDV growth. From these results, the IBV-NDV interference test appears to be a potential diagnostic alternative for identifying IBV field isolates.     

沉默羊传染性脓疱皮炎病毒DNA聚合酶基因的RNAi载体的构建

为了构建用于沉默羊传染性脓疱皮炎病毒(Orf virus,ORFV)DNA聚合酶基因的2种载体,试验选择病毒复制所必需的DNA聚合酶基因作为干扰靶基因,并设计靶基因的扩增引物,经PCR扩增后测序;随后,与Check2载体分别经PmeⅠ和NotⅠ双酶切,酶切后连接产生Check2-靶基因(Check2-D)重组质粒;然后,利用公用网站按照RNAi序列设计的原则,设计RNAi靶点序列并合成靶序列的Oligo DNA,退火形成双链DNA,与经XhoⅠ和HpaⅠ酶切后的pll3.7载体连接产生pll3.7-shRNA质粒;最后,利用磷酸钙法进行pll3.7-shRNA质粒和Check2-D质粒共转染293T细胞,利用双荧光检测系统试剂盒检测其RNA干扰效果。结果表明:成功构建了pll3.7-shRNA质粒和Check2-靶基因重组质粒,干扰效果最好,可达到91.0%。     

靶向新城疫病毒L基因(功能区)的siRNA抑制新城疫病毒的复制

本研究以新城疫病毒（NDV）L蛋白的功能区（P1595、P2103和P3277酶活性中心结构区）序列为RNAi的靶位点,设计、构建了3个特异性的siRNA的真核表达质粒pSi-L6、pSi-L7和pSi—L9,转染到CEF细胞后接种NDV。间接免疫荧光实验结果显示：pSi-L6、pSi-L7和pSi-L9均能抑制NDV抗原蛋白的表达;Real-time PCR检测到转染pSi-L6、pSi-L7和pSi-L9的CEF细胞中L基因的转录水平分别降低79.1％、93．9％和91.3％,P基因的转录水平分别降低73％、86、3％和89．8％;病毒滴度测定表明转染pSi-L6、pSi-L7和pSi-L9质粒的细胞培养上清中病毒的滴度分别低2、19、3、16和5．24倍。本研究中3个特异性的siRNA均能抑制NDV的复制、增殖,表明P1595、P2103和P3277这3个区域对于L蛋白发挥RNA依赖的RNA聚合酶的功能具有重要作用。     

Suppression of bovine viral diarrhea virus replication by single and dual short hairpin RNA-mediated RNA interference

Bovine viral diarrhea virus (BVDV) is one of the most important pathogens to the cattle industry, causing a significant economic loss throughout the world. Despite the wide use of various control measures for BVDV, the disease remains prevalent. In this study, we achieved an efficient inhibition of NADL strain replication by plasmid-mediated shRNA targeting conserved regions of the viral genome. To further enhance the inhibiting efficiency, a dual shRNA expression plasmid, which could simultaneously express two different shRNA, was established and showed stronger inhibitory effects on virus replication. Moreover, the antiviral activity induced by the dual shRNA expression system was also evident on other BVDV-1 subgenotypes (BVDV-1a, BVDV-1b and BVDV-1c). Therefore, the dual shRNA system provides a more powerful strategy for inhibiting BVDV replication in a cross-resistance manner.     

Staphylococcosis of turkeys. 5. Large-scale control programs using bacterial interference

Staphylococcus epidermidis strain 115 was used as an interfering agent to reduce the incidence of staphylococcosis in turkeys. In 1984, the entire Utah turkey population of about 3 million turkeys was exposed at 1 to 10 days and at 4 to 6 weeks of age to aerosols of strain 115. Some staphylococcosis was still observed in range turkeys but appeared to be at a lower rate than in previous years. At processing, about 30% of the turkeys were still colonized with strain 115. A control study was carried out in 1985 to quantitate the level of reduction of staphylococcosis in turkeys treated with strain 115. About 1 million turkeys were treated, and 2 million remained untreated. Flocks from both groups were examined periodically for existing cases of staphylococcosis. Of 174,250 treated turkeys examined, 90 had staphylococcosis on the days examined, whereas 255 of the 183,500 untreated turkeys that were examined had staphylococcosis. Turkeys housed in range sheds had five times the incidence of staphylococcosis that turkeys in enclosed coops had. The gross mortality rate of 200,636 treated turkeys was 2.7% lower (P less than 0.001) than that of 189,450 untreated control turkeys that were monitored.     

Suppression of bovine viral diarrhea virus replication by small interfering RNA and short hairpin RNA-mediated RNA interference

Bovine viral diarrhea virus (BVDV) is a ubiquitous viral pathogen that affects cattle herds' worldwide causing significant economic loss. The current strategies to control BVDV infection include vaccination (modified-live or killed) and control of virus spread by enhanced biosecurity management, however, the disease remains prevalent. With the discovery of the sequence-specific method of gene silencing known as RNA interference (RNAi), a new era in antiviral therapies has begun. Here we report the efficient inhibition of BVDV replication by small interfering (siRNA) and short hairpin RNA (shRNA)-mediated gene silencing. siRNAs were generated to target the 5' non-translated (NTR) region and the regions encoding the C, NS4B and NS5A proteins of the BVDV genome. The siRNAs were first validated using an EGFP/BVDV reporter system and were then shown to suppress BVDV-induced cytopathic effects and viral titers in cell culture with surprisingly different activities compared to the reporter system. Efficient viral suppression was then achieved by bovine 7SK-expressed BVDV-specific shRNAs. Overall, our results demonstrated the use of siRNA and shRNA-mediated gene silencing to achieve efficient inhibition of the replication of this virus in cell culture.     

Feline leukemia virus and feline immunodeficiency virus.

Ophthalmic manifestations of FeLV or FIV infection can occur in all ocular tissues and may be manifestations of direct viral effects or secondary to viral-related malignant transformation. Additionally, the manifestations of common feline ophthalmic pathogens may be more severe and poorly responsive to therapy because of the immunosuppressive effects of FeLV or FIV infection. Prompt diagnosis of underlying viral infection in cats with ophthalmic disease is paramount for accurate diagnosis and prognosis and is required for appropriate therapeutic decision making.