An assessment of the sensitivity of three methods for the detection of rotavirus

Evaluation of two enzyme immunoassays for detection of human rotaviruses in fecal specimens

The two assays evaluated in this study (the Ridascreen rotavirus and the Pathfinder rotavirus) exhibited comparable sensitivities (100%) but highly divergent positive predictive values (93.74 and 57.7%, respectively) when compared on 393 specimens. This difference should be considered when using these tests on collectives with an unknown or low prevalence.

Evaluation of quantitative latex agglutination for detection of Cryptosporidium parvum, E. coli K99, and rotavirus in calf feces

A new methodology for detection of rotavirus, Escherichia coli K99, and Cryptosporidium parvum in bovine fecal samples was developed based on a quantitative latex agglutination technique (QLAT). Calibrated microspheres coated with specific antibodies to 1 of the enteric pathogens are quantitatively agglutinated by the antigens present in diluted fecal sample. The test is performed in a 96-well flat-bottom plate. The samples were tested with a commercial enzyme-linked immunosorbent assay kit prior to being analyzed by QLAT. The calculated sensitivity and specificity are adequate for field conditions, because the amount of the pathogenic agents is generally high. The overall time to perform the test was about 20 minutes.

Proportional morbidity rates of enteropathogens among diarrheic dairy calves in central Spain

Faecal samples from 218 diarrheic dairy calves in 65 dairy herds, selected by convenience, were screened for the presence of rotavirus, coronavirus, Cryptosporidium spp., F5+ Escherichia coli and Salmonella spp. Animals surveyed were from 1 to 30 days old. Cryptosporidium and rotavirus were the most commonly detected agents (52.3% and 42.7% of the samples positive, respectively). F5+ E. coli was detected in the faeces of 11.9% of the calves and bovine coronavirus was detected in the faeces of 7.3% of the calves. Salmonella spp. was only found in the faeces of two calves (0.9%). Mixed infections with two or more agents occurred in 28% of the calves. Concurrent infection of rotavirus and Cryptosporidium was found in 21.6% of the calves. Two tests were used for the detection of rotavirus (a commercial ELISA and PAGE), F5+ E. coli (ELISA and bacterial culture) and Cryptosporidium (ELISA and microscopy). The validity of the commercial ELISA for the detection of rotavirus, F5+ E. coli and Cryptosporidium in faeces from diarrheic calves was evaluated using PAGE, bacterial culture and microscopy as gold standard, respectively. The ELISA showed a very low sensitivity (28.6%) for the detection of F5+ E. coli compared to bacterial culture.

PCR detection of group A bovine rotaviruses in feces

A polymerase chain reaction (PCR) protocol has been developed for identification of bovine group A rotavirus infection in feces. Primers (20mers) complementary to 3' ends of double-stranded RNA genome segment 6 of bovine rotavirus NCDV strain were synthesized and used in PCR. Bovine rotavirus RNA from infected cell culture was employed to optimize the PCR protocol. Rotavirus-negative fecal samples were spiked with known quantities of bovine rotavirus, and the sensitivity of the PCR assay was determined. Fecal samples were extracted with phenol and treated to eliminate unidentified PCR inhibitor(s) in feces, and PCR was performed. PCR products were either visualized on ethidium bromide-stained agarose gels or detected by chemiluminescent hybridization. The sensitivity of the assay was 6 x 10(4) viral particles/ml of feces with ethidium bromide-stained agarose gel visualization or 6 x 10(2) viral particles/ml of feces with chemiluminescent hybridization. The PCR assay was applied to 18 fecal specimens from clinical cases. All 16 clinical samples that were positive for rotavirus by enzyme-linked immunosorbent assay (ELISA) or by ELISA and electron microscopy (EM) were positive by PCR. The 2 samples that were rotavirus negative by ELISA or by ELISA and EM were also negative on PCR analysis.

Survey of rotavirus infection in a dairy herd: comparison between polyacrylamide gel electrophoresis and two commercial tests

A survey of rotavirus infection in a dairy herd with a history of neonatal diarrhoea was carried out. Faecal samples taken from 15 cows before and after calving as well as faeces taken from their calves daily from birth to two weeks of life were tested for rotavirus by polyacrylamide gel electrophoresis (PAGE) and compared with an ELISA and a latex agglutination commercial test. Rotavirus excretion was not detected in faeces from cows around parturition by any of the three tests. However, all of their calves shed rotaviruses during the observation period. The onset of rotavirus excretion determined by PAGE ranged from day 2 to day 8 of life (day 4.8 +/- 1.8 on average) and lasted for 4 to 7 days (5.3 +/- 1.1 days on average). Chi-square test showed a significant association (P = 0.0001) between the presence of rotavirus and the altered consistency of calves faeces. All the three tests showed similar results (overall agreement 92.5%) but discrepancies were detected mainly at the beginning or at the end of the rotavirus excretion period. Results obtained with both commercial kits closely paralleled each other and parameters other than sensitivity, specificity, diagnostic accuracy or predictive values have to be considered as selection criteria.

Comparison of polyacrylamide gel electrophoresis, an enzyme-linked-immunosorbent assay, and an agglutination test for the direct identification of bovine rotavirus from feces and coelectrophoresis of viral RNAs

The dsRNA concentrated polyacrylamide gel electrophoresis (CPAGE) detected rotavirus directly from 19% of 77 stool specimens from diarrheic calves. A commercial enzyme-linked immunosorbent assay (ELISA) detected 25%, latex agglutination test, 23%, and polyacrylamide gel electrophoresis (PAGE), 19%. Establishing CPAGE as the "standard," the commercial ELISA and the latex agglutination test both had higher sensitivity (84%) than PAGE (79%). However, PAGE produced the highest specificity (100%), followed by agglutination (88%) and ELISA (84%). The commercial ELISA had a slightly higher sensitivity than agglutination, PAGE, and CPAGE, but the ELISA specificity was generally lower. The latex agglutination test had a lower sensitivity than ELISA, but specificity was higher. Agglutination had similar negative predictive values (94%), compared with agglutination and PAGe, but had the lowest positive predictive value (a measure of accuracy) (70%). Agreement with CPAGE was highest for PAGE (94.8%), followed by agglutination (87%) and ELISA (84.4%). The calculated percentages of total disagreement with all other tests indicated that ELISA differed from the other rotavirus detection assays in 10.4% of the cases, agglutination in 7.8%, PAGE in 2.6%, and CPAGE in 1.3%. The 2 PAGE assays allowed the detection of atypical rotaviruses from feces based on the characteristic "super-short" migration pattern of the 11 genomic segments of rotaviruses and of other members of the Reoviridae.

Enzyme linked immunosorbent assay for detecting adenoviruses in stool specimens: comparison with electron microscopy and isolation

A commercial enzyme linked immunosorbent assay (ELISA) for detection of adenoviruses in stool samples was compared with the use of electron microscopy and isolation in Graham 293 cells. Although specific, the ELISA was less sensitive than both electron microscopy and isolation. The ELISA had an overall sensitivity of 78% and a specificity of 100%. The sensitivity was related to the amount of virus particles present in the stool sample, increasing to 90% with about 10(7) viral particles/ml of stool. The ELISA was easy to perform, requiring no instrumentation, and is a useful first line test for detection of adenoviruses in stool samples, especially in laboratories without access to an electron microscope. Wider use of ELISAs should help in evaluating the role of adenoviruses in viral gastroenteritis.

Comparison of six commercial kits for the diagnosis of rotavirus infection in man and calves

Seventy-two human and 72 bovine faecal specimens were tested for rotavirus by polyacrylamide gel electrophoresis (PAGE), four commercial enzyme-linked immunosorbent assay (ELISA) kits (Rotascreen, Wellcozyme, Rotazyme II and IDEIA) and two latex agglutination (LA) kits (RotaScreen and Wellcome).

Specimens which were negative by PAGE but positive by one or more of the kits were further examined by direct and immuno-electron microscopy (DEM and IEM). If also negative by DEM and IEM the kit result was considered to be a false positive. Three kits (RotaScreen and IDEIA ELISAs and RotaScreen LA) had specificity and sensitivity greater than 90% on the human specimens but only two (RotaScreen ELISA and LA) had specificity and sensitivity over 80% on the bovine specimens. These kits can therefore be used with reasonable confidence for rotavirus diagnosis, but none of them has any advantage over PAGE other tha speed.

Comparison of a new rapid test (TestPack Rotavirus) with standard enzyme immunoassay and electron microscopy for the detection of rotavirus in symptomatic hospitalized children

We compared a new, rapid, qualitative test for rotavirus (TestPack Rotavirus; Abbott Laboratories, North Chicago, Ill.) with another enzyme immunoassay (Pathfinder Rotavirus; Kallestad Laboratories, Inc., Austin, Tex.) and electron microscopy to determine its clinical utility in a population of symptomatic hospitalized children. In the first part of the study, 100 frozen stool samples were tested. The results after resolution with a blocking reagent showed a sensitivity of only 50% and a specificity of 88% for TestPack Rotavirus. In the second part of the study, we tested TestPack Rotavirus on 100 fresh, unfrozen samples. The results (sensitivity/specificity) were as follows: TestPack Rotavirus, 95/90%; Pathfinder Rotavirus, 84/98%; direct electron microscopy, 63/100%. Although it was not as sensitive or specific as immune electron microscopy, TestPack Rotavirus was more sensitive than direct electron microscopy or Kallestad Pathfinder Rotavirus. TestPack Rotavirus represents a rapid, qualitative method for the detection of rotavirus in stools of symptomatic children.

Comparison of a protein-stabilized Rotazyme II test, with standard Rotazyme II, and electron microscopy for detection of rotavirus

We compared the performance of Rotazyme II with protein-stabilized diluent to standard Rotazyme II and to direct electron microscopy, for the detection of rotavirus. Sensitivity and specificity were: standard Rotazyme II, 79 and 100%, respectively; Rotazyme II with protein stabilizers, both 100%, and electron microscopy, 75 and 100%, respectively. Commercial availability of this product should improve rotavirus detection for laboratories utilizing Rotazyme II methodology.