Prevalence of rotavirus and coronavirus antigens in the feces of normal cows.

The prevalence of rotavirus and coronavirus shedding by adult cows was investigated using capture enzyme-linked immunosorbent assays. Fecal samples from 121 cows in a single herd were tested for the presence of rotavirus and coronavirus, either free or complexed with immunoglobulin. Free rotavirus was not detected in any samples while rotavirus-immunoglobulin complexes were detected in 53 of 121 (44%) samples tested. In contrast, free coronavirus was detected in six (5%) samples and coronavirus-immunoglobulin complexes were detected in 85 (70%) of the samples tested. Thus it appears that subclinical infection of cows by either of these viruses is common, possibly providing a source for infection of the neonate. These assays may therefore provide important information regarding the epidemiology of enteric virus infections and suggest means of improving management to prevent epidemics of neonatal diarrhea.     

Verification of sensitivity and specificity of group a rotavirus detection in piglets faeces with monoclonal blocking ELISA methods

Monoclonal antibodies to group A rotavirus Vp6 protein were prepared and used for verification of three blocking enzyme-linked immunosorbent assay (ELISA) modifications to detect rotavirus A. Selected competitive blocking ELISA (CB-ELISA) and electron microscopy (EM) were used for examination of 194 field faecal samples of piglets affected with diarrhoea. Rotavirus was detected in 43 samples (22.2%) by CB-ELISA method, whereas in 26 (13.4%) samples by EM examination. However, of 26 samples positive by EM, rotavirus A was detected by CB-ELISA in 19 (73.1%) samples; indicating the share of group A rotavirus in all cases of gastroenteritis caused by rotavirus. The sensitivity and specificity of the CB-ELISA was verified both by inclusion of control samples containing transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhoea virus (PEDV) in each analysis and by comparative examination of samples with the commercial ELISA kit. The CB-ELISA sensitivity was positively affected by examination of samples in the presence of chelating agent.     

Agents associated with neonatal diarrhoea in Ethiopian dairy calves

Faeces samples collected from diarrhoeic dairy calves in the first 8 weeks of life were examined for the presence of 5 enteropathogens. The majority of the 108 diarrhoea cases occurred in the first 5 weeks of life and a commercial ELISA kit detected bovine enteric coronavirus (BEC) in 38.9%, serogroup A rotavirus (RV) in 16.7% and K99 (F5) fimbrial adhesin-positive Escherichia coli (K99 ETEC) in 11.1 per cent. Concurrent infections of these enteropathogens were detected in 14.8% of samples (30.8% of samples positive for these agents). No evidence of cryptosporidial infection was found using a differential staining method on faecal smears nor was salmonella excretion detected. On 2 of the 8 farms only BEC was present; the other 6 farms were positive for all 3 agents. It is concluded that BEC is the major infectious cause of neonatal calf diarrhoea in the Ethiopian dairy herds studied with RV and K99 ETEC also contributing to morbidity, either alone or as mixed infections.     

Determination of bovine rotavirus G serotype by polymerase chain reaction

A total of 113 diarrheic samples comprising of 68 buffalo calves and 45 cow calves were screened by RNA-PAGE for the detection of presence of rotavirus. RNA-PAGE analysis of these samples revealed 11 (9.73%) was found positive for rotavirus. Out of 68 faecal samples of buffalo calves tested for viral gastroenteritis, 8 (11.76%) were found positive for rotavirus. Similarly, out of 45 faecal samples of cattle calves tested for viral gastroenteritis, 3 (6.66%) was found positive for rotavirus. Rotavirus-positive samples represented long electropherotype. All RNA-PAGE-positive faecal samples for rotavirus subjected to RT-PCR for VP7 gene, ten samples yielded a specific product of 1,013 bp of VP7 gene. All the PCR-positive samples of the present study were subjected to genotyping with primers for G6, G8 and G10 genotype. All positive samples showed G10 genotype. This indicates that G10 may be predominant genotype among bovine calves in Mumbai region in India.     

ELISA和LAT检测猪血清弓形虫抗体的比较

应用弓形虫重组蛋白rMIC3为抗原建立的酶联免疫吸附试验(ELISA)和乳胶凝集试验(LAT)2种方法,平行检测来自36个猪场的471份猪血清中的抗弓形虫特异性抗体。结果显示,ELISA和LAT对母猪弓形虫抗体的阳性检出率分别为42.86%(21/49)和44.90%(22/49),2种方法的阳性检出符合率为95.45%(21/22);对育肥猪的阳性检出率分别为42.06%(135/321)和43.61%(140/321),2种方法的阳性检出符合率为93.57%(131/140);对仔猪的阳性检出率分别为29.07%(30/101)和45.54%(46/101),2种方法的阳性检出符合率为63.04%(29/46)。结果表明,ELISA和LAT可用于猪弓形虫病的诊断和血清学调查,LAT更适合于仔猪弓形虫病的检测。     

Development of latex agglutination test with recombinant NcSAG1 for the rapid detection of antibodies to Neospora caninum in cattle

Neospora caninum, an apicomplexan protozoan parasite, is recognized as a major cause of abortion in cattle. Surface antigen 1 of N. caninum (NcSAG1) is an important immunodominant candidate for the development of a diagnostic reagent for neosporosis. The present study describes the development and evaluation of a latex agglutination test (LAT) with recombinant NcSAG1 (rNcSAG1) for the detection of antibodies to N. caninum in cattle. The rNcSAG1 gene was cloned in pET-28a and protein was expressed in Escherichia coli BL21 (DE3). Carboxylated latex particles were coated with rNcSAG1 and the degree of agreement between LAT and a commercial enzyme-linked immunosorbent assay (iscomELISA) was evaluated by using of 164 serum samples. Twenty-two (13.4%) and 23 (14.0%) of samples were positive for antibodies to N. caninum by LAT and ELISA respectively. Eighteen of 23 ELISA-positive samples were positive according to the LAT and a substantial agreement (κ=0.77) was found between the results of LAT and ELISA. The results indicated that the LAT with rNcSAG1 would be a rapid, simple, relatively inexpensive and suitable diagnostic test for detection of specific antibodies in N. caninum infection under field conditions. Improvement in purification of rNcSAG1 can reduce probable false positive reactions and so increase the degree of agreement between the LAT and ELISA.     

Comparison of conventional coproscopical methods and commercial coproantigen ELISA kits for the detection of Giardia and Cryptosporidium infections in dogs and cats

Faecal samples of 270 dogs and 100 cats from 3 animal shelters in Germany were comparatively examined using conventional coproscopical methods and commercial coproantigen ELISA kits for the detection of Giardia and Cryptosporidium infections. Giardia cysts were found in 9.5% and 0% of the faecal samples in dogs and cats, respectively, examined once using the ZnCl2-NaCl flotation. However, the Giardia coproantigen ELISA (ProSpecT Giardia Microplate Assay) was positive in 29.5% and 22.4% of the samples from dogs and cats, respectively. Direct faecal smears stained with carbol fuchsin showed Cryptosporidium oocysts in one dog (0.4%) and one cat (1%). In contrast, the Cryptosporidium coproantigen ELISA (ProSpecT Cryptosporidium Microplate Assay) reacted positively in 23% of the samples from dogs and 30% of the samples from cats. Both coproantigen ELISAs were more often positive in coproscopically Giardia-negative canine faecal samples that contained Isospora burrowsi/ohioensis oocysts than in faecal samples without any parasite stage. Possible reasons for these observations are discussed.     

A rapid latex agglutination test for detection of leptospiral antibodies

A rapid semi-quantitative latex agglutination test (LAT) has been standardized for the detection of leptospiral antibodies in serum samples of man and animals. The efficacy of the LAT was compared with the plate enzyme linked immunosorbent assay (ELISA). A total of 276 human serum samples were analyzed by both LAT and ELISA and percentage positives were 84.8 and 85.9%, respectively. Similarly, of 65 animal samples tested, 63.1 and 69.2% positivity were observed in LAT and ELISA, respectively. Even though the ELISA test was slightly more sensitive than LAT, the rapidity, simplicity and economics of the LAT were found to fulfill the requirements of a screening test for leptospiral antibodies.     

Evaluation of ELISA and electron microscopy for the detection of coronavirus and rotavirus in bovine faeces

Enzyme-linked immunosorbent assay (ELISA) was compared with electron microscopy in the examination of faeces from experimental calves and showed 100 per cent agreement in the detection of 19 bovine coronavirus and 15 bovine rotavirus electron microscope positive samples. In a limited field survey of calf diarrhoea 75 selected faeces were examined independently by ELISA and electron microscopy and the agreement between the two tests was 95 per cent for coronavirus and 84 per cent for rotavirus. A further comparison was made with 74 samples submitted for routine diagnosis and this yielded agreements of 82 per cent (coronavirus) and 89 per cent (rotavirus). Factors contributing to discrepant results were examined and the relative advantages and disadvantages of the two tests for routine detection of these enteric viruses are discussed.     

The studies on the aetiology of diarrhoea in neonatal calves and determination of virulence gene markers of Escherichia coli strains by multiplex PCR

The purpose of this study was to determine aetiological agents of diarrhoea in neonatal calves and to investigate virulence gene markers of Escherichia coli strains isolated from calves by multiplex polymerase chain reaction (PCR). Eighty-two diarrhoeic calves and 18 healthy calves were used as subjects. Faeces were taken from the rectums of all the calves and were subjected to bacterial culture. Antigen enzyme-linked immunosorbent assay (ELISA) was performed to detect rotavirus, coronavirus and E. coli K99 in faeces of all the calves. A multiplex PCR was used to characterize E. coli strains in all the calves. Escherichia coli was isolated from 37 faeces samples, Enterococcus ssp. was isolated from 22 faeces samples and Salmonella was isolated from one faeces sample in diarrhoeic calves. Furthermore, only E. coli was isolated from all 18 faeces samples of healthy calves. Of the 37 E. coli isolated from diarrhoeic calves, K99 (18.9%), F41 (18.9%), heat-stable enterotoxin a (STa) (18.9%), Shiga toxin 1 (Stx1; 13.5%) and Shiga toxin 2 (Stx2; 5.4%) and intimin (8.1%) genes were identified by multiplex PCR. Of the 18 E. coli isolated from healthy calves, K99 (16.6%) and intimin (55.5%) genes were identified by PCR. A total of 15 rotavirus, 11 coronavirus and 11 E. coli K99 were detected in diarrhoeic calves by the antigen ELISA. As a result, this study shows that rotavirus, coronavirus, E. coli and Enterococcus ssp. were determined to play a role in the aetiology of diarrhoea in the neonatal calves. K99, F41, STa, Stx1 and Stx2 were found as the most common virulence gene markers of E. coli strains isolated from calves with diarrhoea. Multiplex PCR may be useful for characterization of E. coli isolated from calves.     

Cryptosporidium parvum and Giardia intestinalis in calf diarrhoea in Sweden

The objective of this study conducted in 75 herds was to investigate the presence and significance of Criptosporidium parvum and Giardia intestinalis in Swedish dairy calves in comparison with rotavirus, coronavirus and Escherichia coli K99+. The farmers were asked to collect faecal samples from each heifer calf that had diarrhoea between birth and 90 days of age, and also from a healthy calf of the same age. In total, 270 samples were collected and analysed. C. parvum, either alone or together with G. intestinalis and/or rotavirus, was detected in 16 (11%) and 6 (5%) of the samples from diarrhoeic and healthy calves, respectively. Even though a higher proportion of diarrhoeic calves shed C. parvum, the difference between the groups was not statistically significant (p = 0.067), possibly due to the low number of positive samples. G. intestinalis was found in 42 (29%) of the diarrhoea samples and in 29 (23%) of the samples from healthy calves. Rotavirus and coronavirus were demonstrated in 24% and 3% of the diarrhoea samples, respectively, whereas E. coli K99+ was only found in samples from 2 healthy calves. C. parvum and G. intestinalis were found in samples from calves 7 to 84 days of age and during all seasons. The results confirm that C. parvum is present in Swedish dairy herds and might have clinical significance. G. intestinalis was the most common agent found but the importance of this parasite remains unclear. Both parasites have suggested zoonotic potential and thus warrant further attention. In addition, rotavirus is a major pathogen in neonatal enteritis in Sweden, whereas coronavirus and E. coli K99+ seem to be of less importance.     

Prevalence of bovine group A rotavirus shedding among dairy calves in Ohio.

Fecal samples were collected from 450 neonatal calves, ranging from 1 to 30 days old, between May, 1988 and May, 1989 to estimate the prevalence of bovine group A rotavirus in a stratified random sample of Ohio dairy herds. Calves were from 47 dairy herds chosen to be representative of Ohio herds. Bovine group A rotavirus was detected in fecal samples by a cell culture immunofluorescence test (CCIF) and ELISA. Of 450 samples tested, 46 (10%) were positive by CCIF and 67 (15%) were positive by ELISA. The agreement beyond chance between the 2 assays was good (kappa = 0.65). The overall prevalence rate of rotavirus shedding was 16.4% (74/450). Forty-three percent (29/67) of the samples positive by ELISA were subgroup 1, none were subgroup 2, and the remaining 57% (38/67) could not be assigned to either subgroups 1 or 2. Thirty herds (62.5%) had at least 1 group A rotavirus-positive calf (mean number of samples per positive herd = 12.4), and 17 herds (37.5%) had no rotavirus-positive calves (mean number of samples per negative herd = 6.0). A live oral rotacoronavirus vaccine was used in neonatal calves of only 1 herd and 3 of 17 (17.6%) calves from this herd were positive for group A rotavirus. The percentage of the rotavirus-positive fecal samples from all calves (n = 450) when stratified by fecal consistency was as follows: 28.3% (13/46) had liquid feces; 25.6% (10/39) had semiliquid feces; 23.4% (22/94) had pasty feces; and 10.7% (29/271) had firm feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Epidemiology of typical and atypical rotavirus infections in New Zealand pigs

Polyacrylamide gel electrophoresis (PAGE) and enzyme-linked immunosorbent assay (ELISA) were employed to investigate the epidemiology of typical and atypical rotavirus infections in five piggeries. Of 152 faecal samples examined, 46 (30 per cent) were positive by ELISA for group A rotavirus. Rotaviruses with electrophoretic patterns resembling groups A, B and C were detected. At least two and up to five different rotavirus electrophoretypes (typical and/or atypical) were detected in each of the five piggeries. Out of 152 faecal samples examined, 28 (18 per cent) contained rotaviruses with group A electrophoretypes, 9 (6 per cent) with group C but only 1 with Group B. Six samples contained both group A and group C rotaviruses. No common electrophoretypes of group A or C rotaviruses were detected in these five piggeries. The PAGE technique was also used to analyze group A rotavirus isolated sequentially from another piggery over a three year period. A single electrophoretype was found during the first two years, but in the third year a different electrophoretype was detected.     

Enteric infections in veal calves: A longitudinal study on four veal calf units

Summary

Forty‐five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.