Visualization of horse sickness virus by the fluorescent antibody technique

Horse sickness virus was grown in tissue cultures of monkey kidney cells, and virus was detected by a direct fluorescent antibody technique. Virus was detected at 8 hours in or around the nucleus of cells, and at 24 and 48 hours after infection it was also seen in the cytoplasm.     

A fluorescent antibody technique for studies of mink virus enteritis

Summary A procedure for staining mink virus enteritis antigens with fluorescein isothiocyanate labelled antibody in the epithelial cells of the small intestines of experimentally infected mink is described.The specific viral antigens in these epithelial cells were confined to cytoplasmic bodies.The possible usefulness of the fluorescent antibody technique as a research and diagnostic tool in mink virus enteritis is discussed.     

Foot-and-mouth disease virus: Biological characteristics of virus from bovine carriers

Summary Isolates of FMDV from bovine carriers were compared with the original infecting viruses for changes in biological properties. Occasional marked differences existed between the original virus and succeeding isolates from the same animal. In 2 cattle which were carriers of type A virus and reinfected with type O virus, it was found that some isolates had the antigenic characteristics of both virus types.     

A rapid quantitative fluorescent antibody assay of polioviruses using Tragacanth Gum

Summary A rapid quantitative fluorescent antibody assay of polioviruses using Tragacanth Gum has been worked out.With 1 Figure     

检测Asia I型口蹄疫病毒的胶体金免疫层析法的建立及应用

目的:建立一种快速、简便的检测AsiaⅠ型口蹄疫病毒(FMDV)的胶体金免疫层析法(GICA)。方法:采用柠檬酸钠还原法制备胶体金颗粒,用其标记纯化的AsiaⅠ型口蹄疫抗体后包被在玻璃纤维素膜上,另外将纯化的AsiaI型口蹄疫抗体和纯化的羊抗豚鼠抗体分别包被在硝酸纤维素膜上,作为检测带与质控带。玻璃纤维膜、硝酸纤维素膜按顺序组装成胶体金快速诊断试纸条,通过系列实验验证其灵敏度、特异性、重复性及稳定性。结果:研制的AsiaⅠ型口蹄疫快速检测试纸条对AsiaⅠ型口蹄疫病毒的检测灵敏度为0.116mg/L,对阳性样品进行重复性试验3次检测结果完全相同。交叉反应证实该方法与其他血清型口蹄疫抗原和猪水疱病抗原(SVD)无交叉反应。检测田间样品,GICA与反向间接血凝的定型的符合率为96.87%。稳定性实验证实试纸条可保存12个月。结论:建立的GICA是一种快速、灵敏、特异的FMD抗原检测方法,对基层现场具有广泛应用价值。     

Foot-and-mouth disease virus low-fidelity polymerase mutants are attenuated

Previous studies have shown that RNA viruses can be attenuated by either increased or decreased viral polymerase replication fidelity. Although foot-and-mouth disease virus (FMDV) high-fidelity RNA-dependent RNA polymerase (RdRp) variants with an attenuated phenotype have been isolated using mutagens, no FMDV mutant with a low-fidelity polymerase has been documented to date. Here, we describe the generation of several FMDV RdRp mutants using site-directed mutagenesis via a reverse genetic system. Mutation frequency assays confirmed that five rescued FMDV RdRp mutant populations had lower replication fidelity than the wild-type virus population, which allowed us to assess the effects of the change in replication fidelity on the virus phenotype. These low-fidelity FMDV RdRp mutants showed increased sensitivity to ribavirin or 5-fluorouracil (5-FU) treatment without a loss of growth capacity in cell cultures. In addition, decreased fitness and attenuated virulence were observed for the RdRp mutants with lower fidelity. Importantly, based on a quantitative analysis for fidelity and virulence, we concluded that lower replication fidelity is associated with a more attenuated virus phenotype. These results further contribute to our understanding of the replication fidelity of polymerases of RNA viruses and its relationship to virulence attenuation.     

Detection of Newcastle disease virus in chicken tracheal organ cultures by the fluorescent antibody technique and by the embryonated egg method

An "open-air" chicken tracheal organ culture was used for quantitative studies on detection of Newcastle disease virus (NDV) by the direct fluorescent antibody technique. Despite some quenching of fluorescence by mucus and cellular debris, NDV could be detected in epithelial and lymphoid cells of the trachea. However, efficacy of detection of NDV by reisolation from "open air" tracheal organ cultures in embryonated eggs was higher by a factor of about 100.     

Rapid detection of Pneumocystis carinii using a direct fluorescent monoclonal antibody stain.

A collaborative study was undertaken at two institutions to assess the performance of a direct fluorescent-antibody stain for the detection of Pneumocystis carinii in respiratory specimens from patients with known or suspected human immunodeficiency virus type 1 infections. A total of 163 specimens (125 induced sputa, 37 bronchoalveolar lavage fluids, and 1 tracheal aspirate) from 124 patients were examined by using modified Giemsa (Diff-Quik; Baxter American Scientific Products, Chicago, Ill.) and direct fluorescent-antibody stains. A total of 73 specimens contained P. carinii, which was detected in 66 (92%) of the specimens by using the modified Giemsa and in 71 (97%) of the specimens by using the fluorescent-antibody stain. One bronchoalveolar lavage fluid specimen in which P. carinii was detected only with the fluorescent-antibody stain was determined to be a false-positive based on subsequent clinical evaluation of the patient. Although the overall time for processing and examining specimens stained with either stain was not significantly different for those specimens containing P. carinii, considerably less time was required for microscopic examination of those fluorescent-antibody-stained specimens lacking P. carinii.     

Sensitive radioimmune assay for measuring Aleutian disease virus antigen and antibody

A solid-phase, one-step radioimmune assay was developed which could detect as little as 0.02 microliter of a standard Aleutian disease virus antigen preparation, approximately 3.2 ng of viral protein. Virus antigen was measured in different mink organs and cell types during experimental intraperitoneal infection. The gut and kidney were the first organs in which virus antigen could be detected (day 3 to 6 after infection). On day 6 or later virus antigen was found in spleen, liver, kidney, lymph nodes, peritoneal exudate, and bone marrow cells. With inhibition of antigen binding, a radioimmune assay was developed for antibody detection. Viral antibodies could be detected as early as 3 days after infection. Antibody titers from 1/10(5) to more than 1/10(6) were found in plasmacytotic mink. When the sensitivity of the antibody radioimmune assay was compared with that of other known methods for anti-Aleutian disease virus quantitation, the radioimmune assay was considerably more sensitive, detecting as little as 5 ng of antibody.     

A rapid method for quantitative assay of poliovirus from water with the aid of the fluorescent antibody technique

Summary A method is described for the rapid quantitative demonstration of polioviruses in water with the aid of the fluorescent antibody technique. Identification of the virus is possible after 18–24 hours as compared to 3–5 days required with the plaque count method. Approximately 10 plaque forming units, concentrated from a volume of 40 liters of seeded tap water could be demonstrated by the rapid method. Positive cells were already seen after 6–9 hours; the results were, however, not sufficiently quantitative. The method also showed itself to be less susceptible to bacterial contamination than the current isolation methods. Its possible utilization as a rapid, primary test for viral contamination of potable water is discussed.With 1 Figure