Detection of the K99 antigen of Escherichia coli in calf faeces by enzyme-linked immunosorbent assay (ELISA)

Summary An enzyme-linked immunosorbent assay (ELISA) is presented for the detection of the K99 antigen of Escherichia coli in calf faeces. False-positive reactions were not observed with K99-negative strains and with several viral antigens. Only bovine coronavirus caused slight positive reactions which could be eliminated by a blocking test. As compared with the conventional procedure for the detection of the K99 antigen, ELISA seemed to be at least as sensitive and had the advantage that samples could be stored at -20° C before testing. In addition many samples could be handled at the same time and the results became available quickly. By carrying out the assay as a blocking test, specific antibody against K99 in serum or colostrum could be detected and titrated.     

Identification of a bisegmented double-stranded RNA virus (picobirnavirus) in calf faeces

To determine the incidence of rotavirus infection among dairy herds in the State of S?o Paulo, Brazil, 576 faecal samples obtained from calves aged 1-45 days with and without diarrhoea, reared on 63 dairy cattle farms, were analyzed. Polyacrylamide gel electrophoresis (PAGE) identified 28 samples positive for group A rotavirus, while four samples, two diarrhoeic and two non-diarrhoeic, showed a bisegmented genome with a typical picobirnavirus pattern. Electron microscopy revealed spherical virus particles with a diameter of 37 nm and without a defined surface structure. The present study is the first report of a bisegmented virus identified in cattle in Brazil.     

Detection of transmissible gastroenteritis coronavirus antigens by a sandwich enzyme-linked immunosorbent assay technique

A new sandwich enzyme-linked immunosorbent assay, using monoclonal and polyclonal antibodies, was developed to detect transmissible gastroenteritis virus antigens from cell culture and from intestinal wash or feces obtained from experimentally infected pigs. This technique was shown to be suitable for the detection of virulent field strain unadapted to cell culture. Cross reactions had not been observed with other enteric pathogens, rotavirus, porcine epizootic diarrhea virus, and Escherichia coli.     

Detection of flagellar antigen ofCampylobacter jejuni andCampylobacter coli in canine faeces with an enzyme-linked immunosorbent assay (ELISA) — New prospects for diagnosis

A new diagnostic procedure was developed to detect the flagellar antigen ofCampylobacter jejuni andCampylobacter coli in canine faecal specimens and was tested on faecal samples from random-source dogs obtained from the local dog pound. Extraction of acid-soluble proteins was performed on faecal specimens and the extracted material was evaluated using species-specific monoclonal antibodies in an enzyme-linked immunosorbent assay. The assay detected allC. jejuni orC. coli infected specimens compared with direct selective faecal culture. One of 18 faecal specimens culture-negative forC. jejuni was identified as positive by the assay, i.e. a false positive rate of 1 of 18 (5.6%) and a corresponding specificity of 94.4%. These results suggest that the screening procedure developed to detect flagellar antigens ofC. jejuni andC. coli in canine faecal samples should be further investigated as a diagnostic alternative to culture.Abbreviations ELISA enzyme-linked immunosorbent assay - PBS phosphate-buffered saline - OD optical density     

Detection of astrovirus in the faeces of cats with diarrhoea

Examination by electron microscopy of faeces from two separate cases of young cats with diarrhoea revealed the presence of 28 nm viral particles morphologically consistent with an astrovirus. No visible cytopathic effect was observed when the virus was inoculated into a feline kidney cell culture.     

Hepatic encephalomyelopathy in a calf with congenital portosystemic shunt (CPSS)

A 4-month-old female Holstein Friesian calf was referred to the Veterinary Teaching Hospital, University of Berne, Switzerland for evaluation of ataxia, weakness, apathy and stunted growth. Clinical examination revealed generalized ataxia, propioceptive deficits, decreased menace response and sensibility. Postmortem examination did not reveal macroscopic changes of major organs. Histologically, the brain and the spinal cord lesions were characterized by polymicrocavitation, preferentially affecting the white matter fibers at the junction of grey and white matter and by the presence of Alzheimer type II cells. The liver revealed lesions consistent with a congenital portosystemic shunt, characterized by increased numbers of arteriolar profiles and hypoplasia to absence of portal veins. The pathological investigations along with the animal history and clinical signs indicated a hepatic encephalomyelopathy due to a congenital portosystemic shunt.     

Hound's-tongue (Cynoglossum officinale) poisoning in a calf

Cynoglossum officinale was believed to be responsible for the death of one calf and possibly 5 other calves in a group of 9 calves being fed chopped hay contaminated by this plant. The plant, commonly known as hound's tongue, contains pyrrolizidine alkaloids and has been determined to be toxic to horses fed contaminated hay, but was fed to cattle at the same time with no effect.     

Detection of turkey enteric coronavirus by enzyme-linked immunosorbent assay and differentiation from other coronaviruses

A double-antibody ELISA for the detection of coronaviruses in intestinal contents from turkey poults with diarrhea was developed. Antibodies were raised in rabbits and guinea pigs against a Minnesota isolate of turkey enteric coronavirus (TCV) propagated in embryonating turkey eggs and were purified by density-gradient centrifugation. The specificity of antisera was confirmed by hemagglutination-inhibition and immunoelectron microscopy. Absorption of anti-TCV hyperimmune sera with egg extracts or egg ovalbumin and the use of different dilution and blocking buffers influenced the sensitivity and specificity of the ELISA. Reciprocal cross-reactivity was detected among turkey, chicken, bovine, and murine coronaviruses. Antisera to the transmissible gastroenteritis virus of swine, the rabbit enteric coronavirus, or the human coronavirus strain 299E failed to react with TCV. The TCV cross-reacted only moderately with the avian infectious bronchitis virus and the hemagglutinating encephalomyelitis virus of swine. Investigations with samples from 47 commercial turkey flocks in Quebec with episodes of transmissible enteritis revealed that the ELISA was more sensitive than was electron microscopy for detection of TCV.     

Scanning electron, light, and immunofluorescent microscopy of intestine of gnotobiotic calf infected with calf diarrheal coronavirus.

Intestinal lesions in 2 gnotobiotic calves given (oral inoculation) calf diarrheal coronavirus were studied by scanning electron, light, and immunofluorescent microscopy. The calves were euthanatized at 34 and 73 hours after the onset of diarrhea. Lesions in the small intestine were similar to those reported in animals affected with transmissible gastroenteritis of swine. Small intestinal villi were shortened, some adjacent villi were fused, and villous epithelium was composed of low cuboidal to squamous cells. In the ansa spiralis coli, there were atrophy of the colonic ridges and marked differences in length and spacing of the microvilli on individual epithelial cells.     

竞争性DOT-ELISA法检测TGEV的研究

猪传染性胃肠炎(Porcine transmissible gas-troenteritis,TGE)是由冠状病毒科猪传染性胃肠炎病毒(Transmissible gastroenteritis virus,TGEV)引起的以仔猪呕吐、严重腹泻和高致死率为特征的消化道传染病[1]。本试验利用TGEV N基因原核表达产物重组N蛋白作为抗原检测试剂和以T     

Identification by transfer blot of antigens reactive in the enzyme-linked immunosorbent assay (ELISA) in rabbits immunized and a calf infected with Cryptosporidium sp

Soluble and particulate fractions of Cryptosporidium sp. oocysts from cattle were obtained by homogenization and sonication. Electrophoresis of the soluble fraction in polyacrylamide gels with sodium dodecyl sulfate and silver staining revealed the presence of 41 bands. Enzyme-linked immunosorbent assay (ELISA) of sera from rabbits immunized with either fraction and from a calf 40 days after infection showed that the animals produced specific antibodies. Enzyme-linked immunoelectrotransfer blot tests revealed the presence of five antigens with the rabbit sera and nine with the calf serum. ELISA proved to be an appropriate test for diagnosis of cryptosporidiosis. Selection of reactive antigens may improve the quality of diagnosis and/or reveal the presence of protective materials in the parasite.