Biomedical subjects

R F Bishop

Publications and source records attributed to R F Bishop.

At least 55 records · Page 3Linked to original sources

PubMed1994

Rotavirus serotypes causing severe acute diarrhea in young children in six Australian cities, 1989 to 1992.

Rotavirus VP7 serotypes were identified in stools from 72.9% (1,302/1,784) of hospitalized Australian children in six cities (1989 to 1992) and comprised 1,088 (83.6%) serotype G1 isolates, 84 (6.4%) serotype G2 isolates, 64 (4.9%) serotype G3 isolates, 49 (3.8%) serotype G4 isolates, and 17 (1.3%) isolates of mixed serotypes. The most densely populated cities yielded the greatest diversity of serotypes.

Acute Disease↗

PubMed1993

Sequence conservation within neutralization epitope regions of VP7 and VP4 proteins of human serotype G4 rotavirus isolates.

Serotype G4 rotavirus isolates causing four separate epidemics of severe diarrhoea in young children in Melbourne, Australia (from 1974-1990) were investigated for sequence variation in genes encoding the outer capsid proteins, VP4 and VP7. Complementary DNA of the gene encoding the major outer capsid neutralization antigen, VP7, of eighteen isolates was synthesized and amplified by coupled reverse transcription and polymerase chain reaction. Direct sequencing methods were used to derive the deduced amino acid sequences of the immunodominant A, B, and C neutralization epitope regions of the protein. Limited variation was observed among all isolates. A threonine to asparagine change in region A, at amino acid 96, was associated with altered binding of serotype G4-specific neutralizing monoclonal antibodies. The VP8* region of the outer capsid protein VP4 (containing the proposed serotype-specific neutralization epitopes) was investigated in eight isolates. This region was found to highly conserved both within Melbourne isolates and in relation to the standard strains Wa, P, and VA70. The characteristic periodicity of occurrence of serotype G4 isolates causing severe diarrhoea in Melbourne children is unlikely to be due to changes in neutralization epitopes located on the outer capsid proteins, VP7 or VP4.

Amino Acid Sequence↗

PubMed1993

Intra- and inter-season genetic variability in the VP7 gene of serotype 1 (monotype 1 a) rotavirus clinical isolates.

Nucleotide sequence variation was detected in the VP7 gene of serotype 1 (monotype 1 a) rotavirus isolates collected from children admitted to hospital in Melbourne with acute diarrhoea in 1990 and 1991. Two co-circulating electropherotypes were detected during the 1991 winter epidemic. Using chemical cleavage of mismatches in heteroduplexes, the genes encoding VP7 were found to be genetically stable within each electropherotype during the study period, although differences between the two types were apparent. Direct nucleotide sequencing confirmed this finding. The two electropherotypes exhibited four nucleotide differences in the VP7 gene, only one of which resulted in a substitution in the deduced amino acid sequence. The degree of variation was more pronounced between the 1991 isolates and those from the previous winter, with approximately 3% nucleotide sequence diversity between isolates from both winters. The regions encoding the neutralization epitopes of VP7 were conserved among all isolates. Comparison to the local prototype monotype 1 a strain, RV 4 (isolated from a child admitted to hospital in Melbourne in 1981), implies that the 1990 and 1991 isolates have diverged independently. This suggests that genetically distinct strains emerge from a pool of related viruses to predominate in any given year.

Amino Acid Sequence↗

PubMed1993

Development of candidate rotavirus vaccines.

Candidate rotavirus vaccines tested to date have been developed using a 'Jennerian' approach. Strains of bovine and simian rotaviruses that are naturally attenuated for humans have been assessed and found to confer immunity that is serotype specific in a varying proportion of recipients. The spectrum of protection has been widened by developing reassortants in which the bovine or simian gene coding for VP7 (the major outer capsid protein) has been replaced by the corresponding gene from human VP7 types 1, 2, 3 or 4. Once the protective antigen(s) are identified it may be possible to develop subunit vaccines that eliminate side effects sometimes observed with live vaccine candidates.

Animals↗

PubMed1993

Rotavirus gastroenteritis in infants aged 0-6 months in Melbourne, Australia: implications for vaccination.

The aim of this study was to determine the occurrence of rotavirus infection in infants under 6 months of age who were admitted to hospital in a developed country for treatment of gastroenteritis. Between April 1980 and April 1990, 595 such infants were admitted to the infectious diseases ward at the Royal Children's Hospital, Melbourne, Australia. Faecal specimens were collected within 6 h of admission and were tested for viral, bacterial and protozoal enteric pathogens. Rotaviruses of several serotypes were found in specimens from 15.1% of the infants, adenoviruses in 12.4% and other pathogens in 10.8%. Rotaviruses were found equally often in infants in each 1 month age group. No pathogens were able to be identified in 61.7% of cases. These results show that rotavirus is an important pathogen in infants under 6 months of age who are admitted to hospital with gastroenteritis. Rotavirus vaccination will need to be given during the first 1-3 months of life in developed countries, as is recommended for developing countries. The large group in whom no pathogens were isolated requires further consideration.

Acute Disease↗

PubMed1993

Analysis of homotypic and heterotypic serum immune responses to rotavirus proteins following primary rotavirus infection by using the radioimmunoprecipitation technique.

Three sequential serum samples collected from each of 20 young children with a naturally acquired primary rotavirus infection were assayed by the radioimmunoprecipitation technique for immunoglobulin G antibodies to rotavirus structural and nonstructural proteins of the four major human rotavirus serotypes G1, P1A; G2, P1B; G3, P2; and G4, P2. Fourteen children were infected with a serotype G1 rotavirus strain and six children were infected with a serotype G4 rotavirus strain. Sera were collected from each child in the acute and convalescent periods postinfection and also approximately 4 months later. Serum immune responses to rotavirus core antigens VP2 and VP3, to the major inner capsid antigen VP6, to nonstructural proteins NS35, NS28, and NS26, and to the outer capsid neutralization antigen VP4 of all test strains were detected in the majority of patients. These responses do not appear to be influenced by the G type or P type of the rotavirus strain used in the reactions. Homologous responses to the main neutralization antigen VP7 were detected in 93% of patients with serotype G1 infections and 50% of patients with serotype G4 infections. Heterologous VP7 responses were less frequently detected and were restricted to G1, G3, and G4 serotype rotavirus strains. No responses to VP7 of the serotype G2 rotavirus strain were detected in any patients. Heterotypic immune responses to the neutralization antigens, at least following serotype G1 and G4 infections, therefore appear to consist primarily of responses to VP4 rather than to VP7.

Antibodies, Viral↗

PubMed1992

Typing of human group A rotavirus with alkaline phosphatase-labeled oligonucleotide probes.

Rotavirus (RV) in stools of children less than 1 year of age with diarrhea in Bangkok in 1989 were serotyped by monoclonal enzyme immunoassay (MEIA). RNA extracted from these specimens was tested for hybridization with alkaline phosphatase (AP) and 32P-labeled oligonucleotides constructed from the nucleotide sequences of VP7 of human G types 1 (HuG1Ac), 2 (HuG2Ac), 3 (HuG3Ac), and 4 (HuG4Ac). Of 148 specimens that contained RV, 72% (106/148) hybridized with RV G type specific AP-labeled oligonucleotides compared to 47% (70/148) that were serotyped by MEIA (P less than 0.001). Of 68 specimens that contained only one VP7 serotype (G-type), as identified by MEIA, 94% (16/17) of G1, 90% (27/30) of G2, 57% (4/7) of G3, and 36% (5/14) of G4 RV hybridized with the AP-labeled HuG1Ac, HuG2Ac, HuG3Ac, and HuG4Ac oligonucleotides, respectively. The probes for G1, 2, 3, and 4 RV were specific for each G type. The results of hybridizing specimens with 32P- and AP-labeled oligonucleotides were similar. After transcription and amplification of cDNA of gene 9, AP-labeled RV G type specific oligonucleotides hybridized with 90% (134/148) of RV specimens. The high sensitivity of these nonimmunological techniques could be of value in identifying G types of RV during vaccine trials.

Alkaline Phosphatase↗

PubMed1992

Severity of rotavirus infection in relation to serotype, monotype and electropherotype.

The aim of this study was to determine whether the severity of symptoms associated with rotavirus infection was related to the serotype of the infecting virus. Severity of clinical symptoms in 108 children admitted to hospital for treatment of rotavirus diarrhoea was retrospectively assessed using a scoring system for frequency and duration of vomiting and diarrhoea, degree of fever, acidosis and dehydration, and presence of electrolyte imbalance. Children were 6-30 months old and were fully weaned at onset of symptoms prior to admission to hospital. No other enteric pathogens were detected during the course of the illness. Serotypes and monotypes were identified using a panel of monoclonal antibodies. Gel electrophoresis of rotavirus RNA was performed to determine electropherotypes. Children surveyed were infected with serotype 1 (47), serotype 2 (15) or serotype 4 (46) rotaviruses. Comparisons of severity of clinical symptoms according to infecting serotype revealed no statistically significant differences between serotype 1, 2 or 4 infections. In addition, no differences were detected between different rotavirus strains within each serotype (as judged by electropherotype) including monotypes 1a or 1c. This study failed to reveal differences in virulence between rotavirus strains of different VP7 serotypes infecting young children.

Child, Preschool↗

PubMed1992

Comparisons of rotavirus VP7-typing monoclonal antibodies by competition binding assay.

Three sets of neutralizing monoclonal antibodies (MAbs) used to type the outer capsid protein VP7 of four group A rotavirus serotypes (1 through 4) were compared in competition immunoassays. Reciprocal competition was observed for each of the VP7 type 2-, 3-, and 4-specific MAbs. The VP7 type 1 MAbs exhibited variable competition patterns with other VP7 type 1 MAbs. MAb RV4:3, which has been used to recognize antigenic variants within VP7 type 1 strains, showed reciprocal competition with the four VP7 type 3 MAbs (RV3:1, YO-1E2, 4F8, and 159) using a VP7 type 3 virus (SA11) as antigen. MAb 2C9, also prepared against VP7 type 1, reacted with VP7 type 3 strains and competed with a VP7 type 3 MAb, 159, using RRV as antigen. Use of the different sets of VP7 type-specific MAbs in the enzyme-linked immunosorbent assay permitted the recognition of six antigenic variants within VP7 types 1, 2, and 3 among specimens whose VP7 type could not be determined previously with only one set of typing MAbs. These results demonstrate differences of typing ability among these VP7-specific MAbs and emphasize the need to improve the sensitivity of typing systems by incorporating panels of MAbs reacting with several neutralizing epitopes.

Antibodies, Monoclonal↗

PubMed1992

Role of coproantibody in clinical protection of children during reinfection with rotavirus.

Rotavirus is the major cause of severe, dehydrating infantile gastroenteritis. Infection is limited to the gut, but the relative roles of serum and secretory copro-immunoglobulin A (IgA) in protection are unclear. Specific copro-IgA is predictive of duodenal antirotaviral IgA and correlates with virus-neutralizing coproantibody. Copro-IgA conversion is a more sensitive marker of rotavirus reinfection than seroconversion. We measured rotavirus reinfections by copro-IgA conversion prospectively in 35 children recruited at a time of severe rotavirus illness. The children were followed up longitudinally for 14 to 31 months to determine whether high coproantibody levels correlated with clinical protection against rotavirus disease. Ninety-four percent of the children experienced reinfection, and 38% developed persistent elevations in specific copro-IgA termed plateaus. Plateau children had a higher mean annual rate of rotavirus infection and a lower ratio of symptomatic to total number of rotavirus reinfections than did nonplateau children. The annual rates of rotavirus infection and disease were significantly higher outside the plateau than inside it in children experiencing antirotavirus copro-IgA plateaus. Frequent rotavirus infection of children appears to stimulate production of a specific copro-IgA plateau which correlates with protection against an excess of infection and symptomatic disease.

Age Factors↗

PubMed1991

Reactivities of serotyping monoclonal antibodies with culture-adapted human rotaviruses.

Rotaviruses collected in Bangladesh during 1985 to 1986 were culture adapted and used in a comparative serotyping study with three groups of monoclonal antibodies, all of which reacted with the major neutralization protein (VP7) of serotype 1, 2, 3, or 4. The goals were to determine which monoclonal antibodies most accurately predicted the serotype and why large variations in serotyping efficiencies have occurred with these monoclonal antibodies in previous studies. The 143 rotavirus isolates used in this study belonged to 69 different electropherotypes; and 44, 23, 21, and 55 isolates were identified as serotype 1 through 4, respectively, by neutralization with serotype-specific hyperimmune antisera. Serotyping specificity by enzyme-linked immunosorbent assay with monoclonal antibodies was 100% consistent with results found by neutralization with polyclonal antisera, but large differences were observed in the sensitivities of the different monoclonal antibodies. Monoclonal antibodies 5E8 (serotype 1), 1C10 (serotype 2), 159 (serotype 3), RV3:1 (serotype 3), ST-3:1 (serotype 4), and ST-2G7 (serotype 4) reacted with all the isolates of the corresponding serotype for which there were sufficient infectious particles. Monoclonal antibody 2F1 (serotype 2) was much less sensitive and reacted with only five serotype 2 isolates, but these were among those with the highest titers. Monoclonal antibodies RV4:2 (serotype 1), KU6BG (serotype 1), RV5:3 (serotype 2), and S2-2G10 (serotype 2), on the other hand, failed to react with between one and three isolates of the corresponding serotypes which had high titers, apparently because of epitope changes in these isolates. Effects of epitope variation were, however, most apparent with monoclonal antibodies 2C9 (serotype 1) and YO-1E2 (serotype 3), which reacted with one and no isolates of the corresponding serotypes, respectively. Cross-neutralization of escape mutants indicated that the serotype 1 monoclonal antibodies 5E8, 2C9, and RV4:2 reacted with different but probably overlapping epitopes, as did serotype 2 monoclonal antibodies 2F1, 1C10, and RV5:3, finding that were consistent with the enzyme-linked immunosorbent assay data. Because of epitope variations between rotavirus strains, serotyping with several monoclonal antibodies directed at different epitopes may increase the sensitivity of the method.

Antibodies, Monoclonal↗

PubMed1991

Epidemiology of rotavirus serotypes in Melbourne, Australia, from 1973 to 1989.

Fecal rotavirus strains collected between 1973 and 1989 from 943 children admitted with acute diarrhea to one hospital in Melbourne, Australia, were serotyped by using an enzyme-linked immunosorbent assay. The assay incorporated neutralizing monoclonal antibodies specific for VP7 of the four major human serotypes (1 through 4). A serotype could be assigned to 690 of 943 specimens (73.2%). Typeable strains comprised serotype 1 (72.5%), serotype 2 (6.8%), serotype 3 (2.9%), or serotype 4 (15.4%). Monotypes 1a and 1c comprised 52 and 44%, respectively, of serotype 1 strains. All serotypes and monotypes exhibited polymorphic genomic RNAs. Specimens reacting as mixed serotypes were rare (3.2%) and included intertypic strains (0.7%) and mixed infections (1.0%). Nontypeable strains for which an electropherotype could be determined appeared to be identical with typeable strains present concurrently in the community. Serotypes exhibited various epidemiological patterns. Serotype 1 strains were dominant except during three successive winters when 60 to 90% of the disease was caused by serotype 2. Serotype 4 strains showed an episodic pattern of appearance, recurring at peak incidence approximately every 3 years. Fecal rotavirus strains collected from 145 newborn babies housed in Melbourne obstetric hospitals between 1974 and 1986 were also serotyped. All 135 typeable strains (93.1%) belonged to serotype 3. It is hypothesized that endemic infection with serotype 3 rotaviruses in nurseries for the newborn influenced the epidemiology of rotavirus serotypes responsible for severe clinical disease in young children in the same community.

Age Factors↗

PubMed1990

Serotyping of human group A rotavirus with oligonucleotide probes.

Rotaviruses (RV) in stools of children with diarrhea in Thailand were serotyped by monoclonal enzyme immunoassay (MEIA), and RNA extracted from these specimens were tested for hybridization with oligonucleotides constructed from the nucleotide sequences of VP7 of human serotypes 1, 2, 3, and 4. Of 178 specimens that contained RV as identified with a monoclonal antibody to group A RV, 84% (149/178) hybridized with serotype-specific oligonucleotides, and 42% (74/178) were serotyped by MEIA (P less than .001). Of the 74 specimens that were serotyped by MEIA, 92% (35/38) of type 1, 97% (34/35) of type 2, and the one type 4 RV hybridized with the HuG1Ac, HuG2Ac, and HuG4Ac oligonucleotides, respectively. RV strains identified in children in Thailand in 1987 and 1988 to which a serotype could be assigned by either method were either type 1, type 2, or, less often, type 4. Testing RV for hybridization with oligonucleotides for genes encoding VP7 is an alternate method of determining RV serotypes.

Antibodies, Monoclonal↗

PubMed1990

Comparison of rotavirus immunoglobulin A coproconversion with other indices of rotavirus infection in a longitudinal study in childhood.

In order to determine the sensitivity and reliability of antirotaviral fecal immunoglobulin A (IgA) as an indicator of rotavirus reinfection, the antibody responses to rotavirus of 44 infants with severe rotavirus gastroenteritis recruited on admission to a hospital were studied. Feces were collected daily during hospitalization and weekly thereafter, and sera were obtained every 4 months, for 6 to 32 months (median, 17 months). Antirotaviral IgG, IgA, and IgM were measured by enzyme immunoassay in all samples. Rotavirus antigen, rotavirus-neutralizing antibody, and total IgA were measured in feces. The results showed that use of an IgA index (ratio of specific IgA to total IgA) was unnecessary to identify copro-IgA conversion to rotavirus. The other markers of rotavirus infection tested showed a high level of predictive accuracy of coproconversion in rotavirus-neutralizing antibody. Copro-IgM, serum IgM, and virus in feces were insensitive measures of neutralizing antibody coproconversion. Seroconversion in IgG or IgA was detected in 46% of neutralizing coproconversions. The most sensitive marker, present in 92% of neutralizing coproconversions, was antirotaviral fecal IgA conversion. This correlation of fecal IgA with fecal neutralizing antibody suggests that coproconversions in IgA represent true elevations in antirotaviral IgA with neutralizing capacity. A coproconversion in IgA appears to indicate genuine rotavirus infection. Copro-IgA conversions in feces collected weekly are likely to be more sensitive markers of rotavirus reinfection than are seroconversion and virus detection combined in epidemiological studies of acute diarrhea in children and in rotavirus vaccine trials.

Antibodies, Viral↗

PubMed1990

Homotypic serum antibody responses to rotavirus proteins following primary infection of young children with serotype 1 rotavirus.

The class-specific antibody responses to serotype 1 rotavirus structural proteins were examined by immunoblotting with sera obtained from young children hospitalized with acute rotavirus diarrhea caused by serotype 1. All were believed to be primary infections. Three consecutive samples were obtained from 16 patients during the acute and convalescent phases of the disease and then approximately 4 months later. Immunoglobulin G (IgG)-class antibody responses to two inner capsid proteins (VP2 and VP6) and to the major homologous outer capsid protein (VP7) were detected in all patients. Antibody responses to VP6 were rapid, increased in intensity during 20 to 40 days after the onset of symptoms, and persisted for more than 4 months. Responses to VP2 and VP7 were more delayed, were maximal in convalescent-phase sera, and decreased markedly in intensity 4 months after the onset of symptoms in the majority of children. Two patients with evidence of mixed infection showed persisting high levels of antibody to VP7. Responses to the outer capsid protein VP4 were detected in 67% of patients, peaked at 20 to 40 days after the onset of symptoms, and were no longer detected at 4 months in the majority of patients. It is likely that the immunoblotting technique underestimated responses to VP4. Acute- and convalescent-phase sera (known to contain antirotavirus IgM or IgA measured by enzyme immunoassay) were also examined by immunoblotting. IgM- and IgA-class antibody responses to viral proteins VP2, VP4, and VP7 appeared to be qualitatively identical to those observed for IgG in the same serum samples.

Antibodies, Viral↗

PubMed1989

Epidemiology of rotavirus strains infecting children throughout Australia during 1986-1987. A study of serotype and RNA electropherotype.

The epidemiology of human rotaviruses throughout Australia was studied by examining 344 rotavirus positive faecal specimens using an enzyme immunoassay incorporating serotype specific monoclonal antibodies. Specimens were collected from children less than 5 years old admitted to urban hospitals for treatment of acute diarrhoea during the winter months of 1986 and/or 1987 in Queensland, New South Wales, Victoria, Tasmania, South Australia, and Western Australia. The infecting rotavirus serotype was identified in 229 of 344 (66.6%) specimens. The predominant serotype throughout Australia was serotype 1 which was identified in 218 of 229 (95%) typable specimens. The majority (201 of 218) were identified as monotype 1a strains. Serotype 2 strains were found in Perth, Western Australia in 2 of 12 specimens collected in 1986 and in 6 of 32 specimens collected in 1987. RNA electropherotypes comprising 30 different patterns were detected after co-electrophoresis of 143 of the 218 serotyped strains. Twenty-nine electropherotypes were serologically homogeneous. One electropherotype contained strains with different monotypes including 1a, 1b, and 1d. The results show remarkable serological uniformity, associated with genetic diversity of rotavirus strains identified in widely separated areas of Australia during one winter.

Australia↗

PubMed1989

Rotavirus serotypes causing acute diarrhoea in hospitalized children in Yogyakarta, Indonesia during 1978-1979.

Rotavirus strains in stool specimens from 111 children aged 3-24 months admitted to hospital in Yogyakarta, Indonesia for treatment of acute diarrhoea were serotyped using VP7 serotype specific monoclonal antibodies in a double sandwich enzyme immunoassay. A serotype could be assigned to 59 of 111 specimens (53%). Inability to assign a serotype to 47% of specimens was probably due to loss of the outer capsid during transport of specimens from Indonesia to Australia. All four major human rotavirus serotypes were detected during the 15 month survey from June 1978 to August 1979, including one serotype 1, 5 serotype 2, 31 serotype 3, and 21 serotype 4 strains. One additional strain reacted with serotype 3 and 4 Mabs. Serotype 3 strains showed intratypic variation. The relative frequency of serotypes 2, 3, and 4 varied during the 15 months and appeared to be influenced by climatic changes associated with dry and wet seasons. Vaccine strategies must take account of comparatively rapid changes of predominant serotypes in a community and are only likely to be successful if comprehensive immunity can be established simultaneously against the four major human serotypes.

Acute Disease↗

PubMed1989

Evaluation of end-point titration, single dilution and capture enzyme immunoassays for measurement of antirotaviral IgA and IgM in infantile secretions and serum.

In order to facilitate measurement of antirotaviral IgA in large collections of faeces and secretions, adaptations of enzyme immunoassay methods for estimating antirotaviral IgA and IgM in duodenal fluid, saliva, faeces and serum were studied. To quantitate specific IgA, a single dilution of each sample was assayed. Results were expressed as antirotaviral IgA units derived from a standard curve. Units were calculated by log-logit analysis on computer. There was strong correlation between antirotaviral IgA units and end-point titres in 257 faecal samples (correlation coefficient r = 0.92) and in 182 duodenal fluids and salivary samples (correlation coefficient r = 0.74). The assay was validated using acute and convalescent faeces from children with or without rotavirus infection. Immune conversions in IgA were detected in 33 (75%) of the children by units and 34 (77%) by titres. None of nine children with gastroenteritis due to other infectious agents showed immune conversions to rotavirus. A monoclonal capture IgM assay showed similar end-point titres and numbers of immune conversions when compared with a direct assay for antirotaviral IgM in serum and secretions. Use of the capture method eliminated false-positive reactions with the cell control. The assay for antirotaviral IgA units in secretions is simple, rapid, reproducible and reliable, and has proven of value in longitudinal epidemiological studies of rotavirus coproIgA profiles. Both the capture IgM technique and the single dilution IgA method permit analysis of large numbers of specimens and are appropriate for examination of immune responses to natural rotavirus infection or during vaccine trials.

Antibodies, Viral↗