Endogenous alkaline phosphatase is a cause of non-specific reactions in enzyme-immunoassays for rotavirus based on alkaline phosphatase conjugates.
Explore the source record for details and available documents.
Alkaline Phosphatase↗
Biomedical subjects
G M Beards
Publications and source records attributed to G M Beards.
The diagnostic gap in diarrhoeal aetiology.
It is well established that rotaviruses of group A are the most important cause of severe diarrhoea in children. The causes of most cases of infectious diarrhoea still remain unidentified, however, and there must be other viruses to be found. 'Novel' rotaviruses have recently been discovered, mainly in animals (serogroups B and C in pigs and humans, D in birds, and one or more further groups in sheep and other mammals). Except for the group B virus which has caused widespread outbreaks of quite severe diarrhoea in adults in China (still not reported from outside China) these novel rotaviruses are rarities in the human and probably represent uncommon zoonotic infections. We speculate that the Chinese virus might have arisen by reassortment of genetic segments of animal group B viruses or perhaps by mutation, and so became infectious for man. The problem of identifying and determining the importance of small round viruses is reviewed. It seems likely that the group of small, round structured viruses, including Norwalk and the viruses of plainly calicivirus morphology, are all representatives of a whole group of enteric caliciviruses. Until they can be more easily cultivated it will be difficult to make diagnostic reagents available to all. Astroviruses and genuine parvoviruses have been found by many people in many countries. Astroviruses are probably more important as pathogens in lambs than in children or calves; parvoviruses can only be established as significant in epidemics. The coronavirus-like particles, first found in Vellore and Bristol, are still enigmatic and their role in diarrhoea is uncertain. Toroviridae, recently discovered as causes of diarrhoea in ungulates, do not seem to be at all important as causes of diarrhoea in humans. Possibly fruitful approaches to future searches are outlined: firstly to make more extensive use of immuno-electron microscopy; and secondly to try to improve existing tissue culture systems to make them more sensitive to enteric viruses.
Animals↗
Effects of two negative staining methods on the Chinese atypical rotavirus.
The Chinese atypical (Group B) rotavirus, previously called the adult diarrhoea rotavirus (ADRV), was examined by transmission electron microscopy using either uranyl acetate or potassium phosphotungstate (PTA) as negative stains. Complete rotavirus particles were seen using uranyl acetate which were indistinguishable morphologically from typical rotaviruses. In the same preparations virus particles with differing degrees of degradation were seen after staining with PTA. This effect was not related to pH of the PTA and could be prevented by fixation of the specimen by 0.1 per cent glutaraldehyde. It is concluded that the use of PTA can give rise to falsely negative results for specimens containing this virus.
Glutaral↗
Serotyping of rotavirus by NADP-enhanced enzyme-immunoassay.
A method is described for the serotyping of rotaviruses directly from samples of faeces. Serotype-specific monoclonal antibodies were used in a solid phase enzyme-immunoassay utilising a novel substrate system based on the de-phosphorylation of NADP, followed by cyclic colour reaction. This method is shown to be approximately 5-10 times more specific and sensitive than assays utilising a conventional substrate for alkaline phosphatase, and allowed serotypes to be ascribed to samples which could not be typed by other methods. The value of this method for rotavirus epidemiology and vaccine trials is discussed.
Antibodies, Monoclonal↗
Prevalence of antibody to group B (atypical) rotavirus in humans and animals.
Enzyme-linked immunosorbent assays were developed for the detection of group B rotavirus antigen and antibody. The specificities of both assays were evaluated for antigens and serum specific for rotavirus groups A to D. Serum collected in the United Kingdom from different animal species exhibited the following high prevalence of group B rotavirus-specific antibody: pigs, 97%; cattle, 71%; sheep, 91%; and goats, 91%. In human serum, a lower prevalence of group B-specific antibody was detected; serum from blood donors showed 10% prevalence, and serum from veterinarians showed 4% prevalence.
Animals↗
Detection of Breda virus antigen and antibody in humans and animals by enzyme immunoassay.
Enzyme immunoassays were developed for the detection of Breda virus antibody and antigen. Cattle sera collected in the United Kingdom were found to have a high prevalence of antibody (55%) to Breda virus when examined in a competitive enzyme-linked immunosorbent assay. A low prevalence of antibody was found in pigs (2.2%), and no antibody was found in sheep or goat sera. No antibody to either Breda virus or Berne virus was detected in human sera collected from veterinarians and farm workers. Only 1 of 430 human fecal specimens (0.2%) contained Breda virus antigen detectable by enzyme-linked immunosorbent assay.
Animals↗
Preliminary characterisation of torovirus-like particles of humans: comparison with Berne virus of horses and Breda virus of calves.
Pleomorphic virus-like particles have been observed by electron microscopy in the faeces of children and adults with diarrhoea. Some of these particles were approximately 100 nm in diameter and had a "fringe" of closely applied peplomers approximately 10 nm long; they closely resembled Berne virus of horses and Breda virus of calves, the two representatives of a newly proposed family called the Toroviridae. In one sample a toroidal nucleoprotein-like structure was observed within the particles. For two samples a buoyant density of 1.14 g/ml was determined by centrifugation through a sucrose density gradient. One sample possessed a haemagglutinin for rat erythrocytes. The serological relationship between these different viruses was observed by immune electron microscopy, haemagglutination inhibition, and serum neutralisation. The role of these virus-like particles as candidate pathogens of humans is discussed.
Adult↗
Clinical efficacy of the RIT 4237 live attenuated bovine rotavirus vaccine in infants vaccinated before a rotavirus epidemic.
In a randomized, double-blind, placebo-controlled trial, 331 infants aged 6 to 12 months received orally, at an interval of 1 month, either two doses of live attenuated bovine rotavirus vaccine strain RIT 4237 or equivalent placebo. The vaccinations were carried out during September to November, a non-rotavirus season; only three cases of rotavirus diarrhea occurred in the study group before the vaccinations were completed. During the epidemic season from December to May, 31 patients with clinically significant rotavirus diarrhea required therapy. Five of these were among the 168 vaccine recipients, and 26 among the 160 placebo recipients (P less than 0.001), giving a vaccine protection rate of 82%. The incidence of clinically significant diarrhea from all causes was reduced by 76% in the vaccinees. As determined by an enzyme immunoassay antibody test with homologous virus antigen, seroconversion after vaccination was obtained in 53% of the initially seronegative infants. Clinical protection correlated well with seroconversion, but the vaccinees who failed to seroconvert also had less rotavirus diarrhea than the placebo recipients, suggesting that immunity may be mediated by factors other than serum EIA antibody. Seventeen of the 23 rotavirus isolates in the epidemic season that were typed were of serotype 1, two were of serotype 2, and four were of serotype 3. The protection rates against clinically significant diarrhea were 72%, 100%, and 100% for serotypes 1, 2, and 3, respectively. We conclude that epidemic infantile winter diarrhea associated with human rotaviruses can be significantly reduced by vaccination with the live attenuated RIT 4237 bovine rotavirus vaccine before the epidemic season.
Clinical Trials as Topic↗
Epidemiological aspects of rotavirus infection in young Gambian children.
Rotavirus gastro-enteritis in young Gambian children has its maximum impact on infants after the age of one month, in whom it produces short, well-defined annual winter epidemics with clinical dehydration in up to 18% of those infected. Sporadic infection was observed in neonates who were often asymptomatic, throughout one year but not in the subsequent year. In two consecutive years studied there was a major change from subgroup I, serotype 2 to subgroup II, serotypes 1 and 3. This could have contributed to the failure of children to develop protective immunity against sequential disease following an infection during infancy. If rotavirus morbidity in this community is to be notably reduced by a vaccination programme it would need to be carried out in early infancy prior to the winter season. Evaluation of a type-specific vaccine should include monitoring secular changes in rotavirus serotypes throughout subsequent epidemics.
Diarrhea, Infantile↗
An enveloped virus in stools of children and adults with gastroenteritis that resembles the Breda virus of calves.
Pleomorphic virus-like particles about 100 nm in diameter with a fringe of closely applied peplomers (7-9 nm in length) were observed by electron microscopy in the stools of 20 children and adults with gastroenteritis. In most of the samples no other viral or bacterial pathogens were detected. In form and under immune electron microscopy these virus-like particles resembled the Breda virus isolated from diarrhoeic calves. These objects may be a viral pathogen of humans.
Adult↗
Serological characterisation of human rotaviruses propagated in cell cultures. Brief report.
Fourteen strains of human rotaviruses were propagated in MA 104 cell culture using serum-free medium containing 10 micrograms/ml trypsin. Eleven of the strains were provided by laboratories in Japan and the U.S.A., and the remaining three from our own laboratory. The serological relationships between these strains were determined by rotavirus subgroup-specific enzyme-immunoassays (ELISA) and neutralisation of infectivity with serotype-specific antisera. All the isolates clearly belonged to one of two subgroups, but four distinct serotypes were represented. Furthermore, the recently reported fourth serotype (ST4) and two isolates from Japan (Hochi and Hosokawa) appeared to be related to a South American rotavirus strain reported in 1978 as a probable fourth serotype.
Antibodies, Monoclonal↗
Molecular epidemiology of human rotaviruses. Analysis of outbreaks of acute gastroenteritis in Glasgow and the west of Scotland 1981/82 and 1982/83.
The molecular epidemiology of rotavirus infections in Glasgow and the west of Scotland during 1981/82 and 1982/83 was investigated by electron microscopy, ELISA testing and RNA migration pattern analysis. In 1981/82, rotaviruses of both the 'long' and the 'short' electropherotype (in different variants) co-circulated from the onset throughout the winter peak of the outbreak. Approximately 80% of the children were infected during the first year of life. No differences in incidence were found between sexes. In 1982/83 the isolated rotaviruses were almost exclusively of the 'long' electropherotype (in different variants) and 36% of the children were infected beyond the first year of life. Rotaviruses of the 'long' electropherotype serologically were of subgroup II and serotype 1 and those of the 'short' electropherotype of subgroup I and serotype 2.
Acute Disease↗
Enzyme-linked immunosorbent assays based on polyclonal and monoclonal antibodies for rotavirus detection.
We describe two enzyme-linked immunosorbent assays for rotavirus antigen in feces, which were designed to be as sensitive and specific as possible, and easy to use anywhere. Both are indirect methods, using the antibody capture method, but the second assay utilizes a rotavirus group-specific monoclonal "detecting" antibody instead of the hyperimmune polyvalent guinea pig antisera used in the first assay. Both tests were found to be more sensitive than electron microscopy for detecting virus. To develop these tests, solid phase, antiserum production methods, treatment of the test antigen with EDTA, substrate, stability of reagents, and the need for confirmatory "blocking" tests were all examined. The first assay described is that used at present by the World Health Organization for their worldwide diarrheal disease control program.
Animals↗
Serotyping and subgrouping of rotavirus strains by the ELISA test.
A method is described for the serotyping and subgrouping of rotaviruses by enzyme-linked immuno-sorbent assay (ELISA). For the isolates tested "blind" under code in parallel the serotyping results obtained by ELISA and serum neutralization of fluorescent focus formation were the same. After absorption of the typing antisera with purified heterotypic rotavirus, up to 128-fold differences in titres between isolates were observed in the ELISA test. The results of serotyping and subgrouping, by ELISA, of strains previously described and characterized by the authors' and other laboratories are also given. An attempt is made to correlate the serological findings with variations between virus strains based upon patterns of genome molecular weights as revealed by polyacrylamide gel electrophoresis. The application of this ELISA technique to epidemiological studies and vaccine research is discussed.
Animals↗
Polymorphism of genomic RNAs within rotavirus serotypes and subgroups.
The genome of human rotaviruses is composed of 11 segments of double stranded RNA. Analysis by polyacrylamide gel electrophoresis of the genomic RNA from a number of strains of the same serotype has demonstrated a significant polymorphism in the migration pattern. However, two strains differing from each other in serotype were found to have apparently identical RNA migration patterns. It is concluded that serotype cannot be deduced from RNA migration patterns. Degrees of polymorphism have been observed within each of three known human rotavirus serotypes.
Electrophoresis, Polyacrylamide Gel↗
A method for the purification of rotaviruses and adenoviruses from faeces.
Rotaviruses and non-cultivable enteric adenoviruses were purified from large volumes of faecal extracts using polyethylene glycol precipitation, centrifugation through 45% w/v sucrose and segregation by density in a cesium chloride density gradient. Yields were high and the preparations were pure enough to use in the production of type-specific antisera and in viral polypeptide analysis. Human rotavirus particles of density 1.38 g/ml were shown to be non-infectious for LLC-MK2 tissue culture cells.
Adenoviruses, Human↗
The influence of divalent cations on the stability of human rotavirus.
The influence of divalent cations on the stability of human rotavirus was investigated using the indirect immunofluorescence (FA) technique in LLC-MK2 cells to titrate infectivity. Rotavirus infectivity was stabilized by calcium and strontium ions in solution but not by magnesium ions. Rotavirus isolates were found to be much less stable at 37 degrees C than at + 4 degrees C or 20 degrees. A study of virus morphology at intervals during the course of the experiment and treatment with the chelating agents EDTA and EGTA suggests that loss of infectivity coincides with the removal of the outer capsid layer and that calcium may be required to maintain virus integrity.
Animals↗
An outbreak of rotavirus diarrhea among a nonimmune, isolated South American Indian community.
During July-August 1977, an outbreak of acute diarrhea occurred in an unusually isolated population, the Tiriyó Indians, who live in the north of Pará, Brazil, near the border with Surinam. Diarrhea was reported by 157 (70%) of the 224 Indians living in the village during the epidemic. There was one fatal case in a one year old child. Rotavirus was detected by electron microscopy in one fecal specimen collected from an acute case of diarrhea. Seroconversions were noted in 127 out of 168 (75.6%) paired serum samples tested for rotavirus antibody by counter-immunoelectrophoresis. With immunofluorescence based neutralization tests, rotavirus serotype 1 (Birmingham) was shown to be associated with the outbreak. The infection also boosted type 3 antibodies but this was most apparent in persons with pre-existing type 3 titers and the boost was not as great as with type 1. All age groups were affected. The proportion symptomatic was greatest in young children.
Adolescent↗