Detection of human rotavirus by nucleic acid analysis in comparison to enzyme-linked immunoassay and electron microscopy

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.

Direct detection and characterization of rotavirus into subgroups by dot blot hybridization and correlation with ‘long’ and ‘short’ electropherotypes

BACKGROUND

Enzyme-linked immunosorbent assay (ELISA) and polyacrylamide gel electrophoresis (PAGE) of viral RNA are well-established methods for detection of rotavirus in stool samples. Dot-blot hybridization has also been found to be a sensitive and specific technique for detection and characterization of rotaviruses.

OBJECTIVES

To compare the performance of dot blot hybridization with ELISA and PAGE for detection of rotavirus in stool samples. To assess the use of dot blot hybridization for characterization of rotaviruses into subgroups.

STUDY DESIGN

Stool samples were collected from 214 children presenting to the hospital with acute diarrhoea. These were assayed for rotavirus by ELISA and PAGE. Dot-blot hybridization was done with full length cloned radiolabelled c-DNA probes of gene segment 6 of SA-11 (subgroup I) and Wa (subgroup II) rotaviruses.

RESULTS

Out of 214 stool samples 134 were found to be positive for rotavirus by one of the three methods. Among these 134 positive specimens 114 were positive by dot blot hybridization, this included 18 specimens which were positive only by dot blot assay. One-hundred-and-twelve of these 114 specimens could be subgrouped. Fifteen of these were classified as subgroup I, 97 as subgroup II and two had a dual subgroup specificity. Three subgroup 1 strains had a 'long' RNA pattern, whereas one subgroup II strain had a 'short' RNA pattern which has not been reported earlier for human rotaviruses.

CONCLUSION

Dot blot hybridization as described here is a sensitive and specific assay for detection and subgrouping of rotaviruses. However, as there is a considerable genomic diversity among rotaviruses, the panel should include probes from all the genotypes of gene segment 6.

A study of human reovirus IgG and IgA antibodies by ELISA and western blot

Immunoglobulin A and G reactivities to human reovirus were investigated comparatively by Western blot and ELISA in a collection of 120 serum samples. Five different reovirus polypeptides of molecular weights of 127, 79, 54 42 and 40 kDa were visualized by polyacrylamide gel electrophoresis. Of 80 anti-reovirus ELISA-IgG positive serum samples, 97.5% and 15.0% reacted with one or more virus-specific bands in the IgG and IgA Western blot respectively. The 127 and 79 kDa proteins reacted with 100% and 96.2% of the IgG Western blot-positive serum samples (n = 78). IgG reactivities to the 40, 54 and 42 kDa proteins were detected in 96.2%, 80.8% and 20.5% of the immunoblot-positive sera. Compared to the Western blot, the ELISA had a specificity of 94.9% for IgG and 96.3% for IgA detection. The sensitivity of specific IgG and IgA detection by ELISA were 96.3% and 100%, respectively. Using the ELISA, a seroepidemiological survey was carried out on 850 sera collected from October 1989 to September 1992. The overall prevalence of reovirus IgG and IgA antibodies were 53.5% and 15.5% respectively. An age dependent increase of the seroprevalence of anti-reovirus IgG was observed. In contrast, the prevalence of IgA antibodies remained constant during childhood. Seroprevalence peak levels were observed in the 9-11, 20-29, 40-49 and > or = 60 years age group. The results of the study suggest that antireovirus IgG antibodies may persist lifelong, whereas IgA antibodies are detectable for a short time and may indicate a recent reovirus infection. The development of a sensitive and specific ELISA assay for the detection of class-specific immunoglobulins permits further investigation of reovirus infections and may contribute to improving the serological diagnosis of recent infection.

Detection of human rotavirus by using an alkaline phosphatase-conjugated synthetic DNA probe in comparison with enzyme-linked immunoassay and polyacrylamide gel analysis

An alkaline phosphatase-conjugated synthetic oligodeoxyribonucleotide probe was compared with polyacrylamide gel electrophoresis (PAGE) detection of rotavirus RNA as well as an enzyme-linked immunosorbent assay (ELISA) for the detection of rotavirus in stools from young children with gastroenteritis. The synthetic probe did not cross-react with bacterial causative agents of diarrheal disease. Extraction of viral RNA from stool samples with a phenol-chloroform mixture was suitable for most samples. In some cases fecal pigments interfered with the reaction of the probe with viral RNA. The use of ion-exchange chromatography to further purify viral RNA removed contaminating pigments and increased the sensitivity of the probe assay. Of 260 stool specimens, 77 (30%) were positive for rotavirus when tested by PAGE analysis of rotavirus RNA. The synthetic probe identified 71 rotavirus specimens when RNA obtained by phenol-chloroform extraction followed by chromatographic purification was used (sensitivity, 91.0%; specificity, 96.7%). The ELISA results also agreed well with the electrophoretic analysis (sensitivity, 98.7%; specificity 94%) and the probe assay (sensitivity, 90%; specificity, 100%). Discordant results between the ELISA and the probe assay were examined further by electron microscopy and PAGE analysis of viral RNA. The positive and negative predictive values of the probe assay in comparison with PAGE were 92.2 and 96.1%, respectively. Rotaviruses showing both long and short RNA electrophoretic patterns were detected by the probe. The probe assay coupled with chromatographic purification of rotavirus RNA is an effective method for detecting rotavirus and compares favorably with PAGE analysis and ELISA.

Polyacrylamide gel electrophoresis of RNA compared with polyclonal- and monoclonal-antibody-based enzyme immunoassays for rotavirus

Polyacrylamide gel electrophoresis (PAGE) of rotaviral RNA, a sensitive and highly specific test for detecting rotavirus in stool, was compared with two commercially available enzyme immunoassays (EIAs), monoclonal (Pathfinder) and polyclonal (Rotazyme II). Stool samples from 204 children with nosocomial diarrhea were tested for rotavirus by both EIAs and by PAGE of RNA extracted from raw stools or 10% stool suspensions. Samples which tested positive by either EIA but were negative by PAGE were subjected to blocking EIA with rabbit or goat anti-SA11. Rotavirus was detected by PAGE and Pathfinder in 62 stools, but only 47 of these were positive by Rotazyme II. Blocking assays of EIA-positive, PAGE-negative samples suggested the presence of rotavirus in four additional stools. Sensitivity and specificity measured against PAGE and blocking assays were: Pathfinder, 0.985 and 0.934; and Rotazyme II, 0.731 and 0.927, respectively. False-positive rates were 0.134 for Pathfinder and 0.149 for Rotazyme II. The specificity and rate of false-positive results of Pathfinder were improved by using an adjusted optical density cutoff 4.36 times greater than that recommended by the manufacturer (specificity, 0.993; sensitivity, 0.985; false-positive rate, 0.015).

Comparison of seven kits for detection of rotavirus in fecal specimens with a sensitive, specific enzyme immunoassay

A sensitive, specific enzyme immunoassay (SSEIA) was compared to four commercial, enzyme-linked immunosorbent assay (ELISA) kits and three latex agglutination assay (LAA) kits: (1) Rotavirus EIA, International Diagnostic Laboratories (IDL), (2) Pathfinder, Kallestadt (KAL), (3) Rotavirus Bio-EnzaBead, Litton (LIT), (4) Rotazyme II, Abbott (RTZII), (5) Slidex Rota-Kit, bioMerieux (SRK), (6) Meritec-Rotavirus, Meridian (MER), and (7) Rotalex, Medical Technology Corporation (RLX). The SSEIA was chosen as the reference method due to its greater sensitivity in comparison to immunoelectron microscopy and polyacrylamide gel electrophoreses of viral RNA segments. Upon evaluation of 136 specimens (of which 44 were positive by SSEIA), the ELISA kits (LIT, KAL, IDL, and RTZII) had sensitivities of 80%, 98%, 91% and 84%; specificities of 95%, 78%, 100%, and 88%; positive predictive values (PPV) of 88%, 68%, 100%, and 77%; and negative predictive values (NPV) of 91%, 99%, 96%, and 92%. When compared with SSEIA, the three LAA tests (SRK, MER, and RLX) had sensitivities of 73%, 75%, and 62%; specificities of 99%, 93%, and 95%; PPVs of 97%, 85%, and 84%; and NPVs of 88%, 89%, and 84%. LAA test results appeared to be reliable, if positive, but the sensitivities of these tests were less than those of the ELISA tests. The ELISA tests that employed specimen specific negative controls were superior in minimizing false positive reactions.