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D R Snodgrass

Publications and source records attributed to D R Snodgrass.

At least 37 records · Page 2Linked to original sources
PubMed1991

Homotypic and heterotypic serum and milk antibody to rotavirus in normal, infected and vaccinated horses.

The homotypic and heterotypic antibody response to rotavirus was determined in three pony mares and their foals. The normal concentrations of anti-rotavirus antibodies in mares' milk and mares' and foals' serum over the first 10 weeks post-partum were measured using IgA, IgG and rotavirus serotype-specific enzyme linked immunosorbent assays. Experimental infection of the foals with serotype 3 equine rotavirus produced a rapid, serotype-specific response which peaked 10 days after infection and a slower heterotypic response which peaked 32 days later. In contrast, vaccination of the mares with an inactivated, adjuvanted serotype 6 bovine rotavirus produced a heterotypic response similar to that of the homotypic response in both serum and milk, although the predominant response in serum was IgG, while in milk it was IgA. These results suggest that non serotype-restricted passive protection of foals against rotavirus may be achieved by parenteral vaccination of mares.

Animals↗
PubMed1991

Monoclonal antibodies differentiate between the haemagglutinating and the receptor-destroying activities of bovine coronavirus.

A relatively simple and sensitive method is described which enables the effect of monoclonal antibodies (MAbs) on the receptor-destroying enzyme (RDE) and the haemagglutination (HA) activity of bovine coronavirus (BCV) to be analysed in one assay. A lysate of HRT-18 cells infected with the L9 strain of BCV was found to have a higher RDE:HA ratio than purified virus. At 4 degrees C the lysate induced an HA pattern which completely disappeared upon raising of the temperature to 37 degrees C. This L9-infected cell lysate was used to determine the HA inhibition (HAI) titres of MAbs directed against the surface glycoproteins S and HE of BCV. Thereafter, the test plates were incubated at 37 degrees C to enable the ability of the MAbs to prevent elution of virus from BCV-erythrocyte complexes to be assessed. No inhibition of RDE was detectable with MAbs against glycoprotein S, which had HAI titres ranging from 1:16 to 1:128. On the other hand, MAbs directed against glycoprotein HE had similar HAI titres, but they inhibited elution of 8 HA units of BCV at titres of up to 1:65,000.

Animals↗
PubMed1991

Serological and genomic characterization of L338, a novel equine group A rotavirus G serotype.

A group A rotavirus designated L338 was isolated from the faeces of a diarrhoeic foal and was compared to 11 standard G serotype strains of group A rotaviruses by cross-neutralization. It was clearly distinct from serotypes G1 to G11 and thus representative of a novel rotavirus G serotype tentatively designated G13. The nucleic acid sequence of the virion protein 7 (VP7) coding region was determined and the deduced amino acid sequence compared to published sequences. Within VP7 regions A and B, L338 was clearly distinct from serotypes G1 to G12 (excluding G7 which has not been sequenced), but region C was very similar to those of G3 and G8. This further questions the significance of region C in determining serotype specificity of at least three distinct rotavirus G serotypes.

Amino Acid Sequence↗
PubMed1991

The prevalence of enteric pathogens in diarrhoeic thoroughbred foals in Britain and Ireland.

A survey of 77 normal and 326 diarrhoeic foals in Britain and Ireland from 1987 to 1989 revealed a significantly higher prevalence of Group A rotaviruses and Aeromonas hydrophila in diarrhoeic foals. The prevalence of cryptosporidia, potentially pathogenic Escherichia coli, Yersinia enterocolitica and Clostridium perfringens was similar in normal or diarrhoeic foals. Rotaviruses had a similar prevalence in all age groups of scouring foals up to three months of age, with an overall prevalence of 37 per cent among diarrhoeic foals. The number of cases of diarrhoea varied considerably from year to year, but in all three years of the survey rotavirus was a significant pathogen. A comparison of diagnostic tests for rotavirus in the faeces showed electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) to have similar sensitivity. The Rotazyme ELISA test kit was found to have the same sensitivity as a combination of EM and PAGE. A. hydrophila had an overall prevalence of 9 per cent among diarrhoeic foals, although its prevalence was higher in some age groups. A. hydrophila has not been established previously as a significant enteric pathogen in foals. Other putative pathogens found at very low prevalence were coronavirus, the putative picobirnavirus, Campylobacter spp. and Salmonella spp. No evidence was found of synergistic effects between rotavirus, cryptosporidia and potentially pathogenic E. coli. Neither coccidia nor non-Group A rotaviruses were found in any of the samples examined.

Aeromonas↗
PubMed1991

Homotypic and heterotypic serological responses to rotavirus neutralization epitopes in immunologically naive and experienced animals.

Gnotobiotic or specific-pathogen-free animals with no previous exposure to rotavirus were vaccinated with strain UK, serotype G6. The highest serological response was to homologous virus; significant but lower responses occurred to viruses with either VP4 or VP7 related to that of vaccine virus; responses to other viruses were of low titer or infrequent. Adult cows vaccinated with UK virus produced increased titers of antibody to all rotavirus serotypes. The increases in titer to homologous virus and to other natural and reassortant viruses sharing VP7 with the vaccine virus were significantly higher than those to all other viruses. These results suggest the presence of common epitopes which are not well recognized in primary infections.

Animals↗
PubMed1990

A comparison of bovine coronavirus strains using monoclonal antibodies.

Eight monoclonal antibodies (MAbs) were raised against a bovine coronavirus (B.C.V.) which had been isolated in Scotland and was designated S2. The MAbs were divided into two groups on the basis of their reactions with S2 virus in indirect immunofluorescence (I.F.), neutralisation and haemagglutination inhibition (H.A.I.) tests. Five of the MAbs were positive by all three tests but failed to bind to proteins in Western immunoblotting experiments. The remaining three MAbs were positive in I.F. tests only, two of which were shown to bind to the 52K nucleocapsid protein by Western immunoblotting. Different patterns of antigen distribution within infected cells were demonstrated when the MAbs were used in the I.F. test. However only minor strain variations were detected by I.F. and H.A.I. tests when the MAbs were tested against each of five cell culture adapted strains of B.C.V. Twenty-nine isolates of B.C.V. have been grown in neonatal calf tracheal organ cultures: attempts are being made to further characterize these isolates.

Animals↗
PubMed1990

Rotavirus serotypes 6 and 10 predominate in cattle.

Calf fecal rotavirus strains were serotyped in enzyme-linked immunosorbent assays, using monoclonal antibodies to the VP7s of serotypes 1, 2, 3, 5, and 6 and to the VP4 of B223 (designated serotype 10). Sixty-six percent of 162 samples were typed as serotype 6, and 7% were serotyped as serotype 10. Most of the untyped strains did not react with a monoclonal antibody directed to a common VP7 epitope, indicating insufficient virus present in the samples. However, seven untyped samples that did react with this antibody were adapted to culture and typed, and six of these also proved to belong to serotype 6 or 10. Two of these viruses belonged to a monotype within serotype 6 that did not react with the serotype 6 monoclonal antibody. The seventh isolate reacted in cross-neutralization tests with serotype 8 viruses. Bovine rotaviruses from the United Kingdom, Federal Republic of Germany, and Japan that had been shown previously to be distinct from serotype 6 were compared in neutralization tests with B223 from the United States. These viruses proved to be a closely reacting group distinct from all other rotavirus serotypes, justifying the establishment of serotype 10 as the second major type of bovine rotavirus.

Animals↗
PubMed1990

Diversity of rotavirus serotypes in Mexican infants with gastroenteritis.

One hundred thirty-two stool specimens from infants with rotavirus gastroenteritis hospitalized in two Mexican cities (Mexico City and Mérida) were examined by serotype- and subgroup-specific enzyme immunoassays. Among them, 38 (29%) were serotype 1, 15 (11%) were serotype 2, 13 (10%) were serotype 3, 22 (17%) were serotype 4, none was serotype 5 or 6, and 44 (33%) could not be serotyped. By subgrouping, 121 specimens were characterized as follows: 24 (18%) were subgroup 1, 97 (74%) were subgroup 2, and none had both subgroup specificities. While serotype 1 rotavirus predominated in the Mexico City area for 4 consecutive years (1984 to 1987), serotype 4 predominated in Mérida during the single epidemic season studied (1985). These data demonstrate that all four primary human rotavirus serotypes circulated in Mexico, with serotype 1 being the most prevalent. The seroneutralization responses of 14 of the 22 patients infected with serotype 4 strains had been previously studied. Of these 14 infants, 11 appeared to have primary infections, as indicated by absence of neutralizing antibodies in the acute-phase sera and their young age (8 months on average) at the time of illness. Seven patients seroresponded to serotypes 1 and 4; two seroresponded to serotypes 1, 3, and 4; three seroresponded to serotype 1; and two had low-level seroresponses to serotype 3 or 4. These data indicate that heterotypic neutralizing antibody responses occur frequently following infection with serotype 4 rotaviruses.

Antibodies, Monoclonal↗
PubMed1990

Serological and genetic characterization of bovine rotaviruses in Thailand by ELISA and RNA-RNA hybridization: detection of numerous non-serotype 6 strains.

A total of 62 fecal specimens positive for rotavirus were collected from diarrheic cows in Thailand in 1988 and 1989. The antigenic properties of rotaviruses in stool were examined by enzyme-liked immunosorbent assays using specific monoclonal antibodies directed at VP4, VP6 or VP7: all the bovine rotavirus strains were determined as subgroup I; none of the strains were reactive with serotype 6-specific monoclonal antibody; and different reactivities of the bovine strains with two anti-VP4 monoclonal antibodies were observed. Polyacrylamide gel electrophoresis of viral RNA exhibited three different RNA electropherotypes. In RNA-RNA hybridization experiments using cell culture-adapted three strains as well as a reference bovine strain (NCDV), RNA from the Thai bovine strains showed very low homology to that from NCDV; only three or four RNA segments were hybridized between the RNAs from Thai samples and NCDV. These results suggested that bovine rotaviruses isolated in Thailand are serologically and genetically distinct from a reference serotype 6 bovine strain, NCDV.

Animals↗
PubMed1989

A serological comparison of bovine coronavirus strains.

Two bovine coronavirus (BCV) strains from diarrheic calf faeces were adapted to grow in HRT 18 cells and compared in immunofluorescence (IF), haemagglutination inhibition (HAI) and neutralisation (NT) tests with three other strains of BCV and a human coronavirus (HCV) strain obtained from other laboratories. Polyclonal antisera against these 6 viruses were raised in rabbits. No significant differences between viruses were detected by IF. In the HAI test the HCV strain was distinguishable from the 5 BCV strains and serological variation between the BCV strains was shown. HCV could be distinguished by NT test, but all BCV isolates were similar. Two monoclonal antibodies prepared against one of the BCV strains distinguished HCV in all three assays, and detected varying relationships between BCV strains.

Animals↗
PubMed1989

Serological characterization of bovine rotaviruses isolated from dairy and beef herds in Argentina.

Bovine rotaviruses isolated from beef and dairy herds in Argentina were serotyped by the immunoperoxidase focus reduction assay as previously described (G. Gerna, M. Battaglia, G. Milenesi, N. Passarani, E. Percivalle, and E. Cattaneo, Infect. Immun. 43:722-729, 1984). Three strains from beef herds were related to the UK and NCDV bovine rotavirus strains defined as serotype 6 (Y. Hoshino, R. G. Wyatt, H. B. Greenberg, J. Flores, and A. Z. Kapikian, J. Infect. Dis. 149:694-702, 1984). Two other strains from dairy herds were classified as bovine viruses related to the bovine B223 strain reported by Woode and co-workers (G. N. Woode, N. E. Kelso, T. F. Simpson, S. K. Gaul, L. E. Evans, and L. Babiuk, J. Clin. Microbiol. 18:358-364, 1983) in the United States. A serotyping antibody-capture enzyme-linked immunoassay to detect serotype 6 rotavirus using a serotype 6-specific monoclonal antibody was developed and evaluated for strain characterization. Characterization of 72 group A rotavirus-positive fecal samples from beef herds and 43 fecal samples from dairy herds showed a predominance of serotype 6 rotavirus in beef herds but both serotype 6 and non-serotype 6 rotaviruses in dairy herds. Analysis of genomic double-stranded RNA by polyacrylamide gel electrophoresis showed that when outbreaks were caused by one serotype only a single electropherotype was present in all samples.

Animals↗
PubMed1987

Enteric campylobacter infection in gnotobiotic calves and lambs.

Gnotobiotic calves and lambs were infected orally with Campylobacter jejuni, C coli or C hyointestinalis to assess pathogenicity. All animals were successfully colonised and excreted mucoid faeces but showed no other clinical signs. Campylobacters colonised the large intestine better than the small intestine, in which bacterial numbers decreased with time after infection. Campylobacters were found occasionally in the lumen of crypts in close proximity to epithelial cells and included in a mucus-like material. Lesions were mostly in the large intestine in calves whereas in lambs they were present in the ileum. In animals inoculated with C jejuni or C coli scattered crypt abscesses, focal inflammatory infiltrates in the lamina propria and goblet cell discharge were found. In lambs inoculated with C hyointestinalis only minor changes were found in the small intestine. Serum antibody response was either absent or present at a low level only from the 19th day after infection.

Animals↗
PubMed1986

Aetiology of diarrhoea in young calves.

Faeces samples were collected from 302 untreated calves on the day of onset of diarrhoea and from 49 healthy calves at 32 farms experiencing outbreaks of diarrhoea. At least four diarrhoeic calves were sampled on each farm, and samples were examined for rotavirus, coronavirus, cryptosporidium, enterotoxigenic Escherichia coli and Salmonella species. Although all these enteropathogens were excreted more frequently by the diarrhoeic than by the healthy calves, the difference was significant overall only for rotavirus. Rotavirus was excreted by 18 per cent of healthy calves, coronavirus by 4 per cent, cryptosporidium by 14 per cent, and no enterotoxigenic E coli or Salmonella species were detected. The most common enteropathogen in diarrhoeic calves was rotavirus, which was excreted by more than half the diarrhoeic calves on 18 farms. Coronavirus was excreted at a similar high prevalence on one farm, cryptosporidium on five farms and enterotoxigenic E coli on three farms. Concurrent infection with two or more microorganisms occurred in 15 per cent of diarrhoeic calves. There was no difference in the isolation rate of campylobacters between diarrhoeic and healthy calves.

Animals↗
PubMed1986

Evaluation of a combined rotavirus and enterotoxigenic Escherichia coli vaccine in cattle.

A vaccine of rotavirus and K99 antigen from enterotoxigenic Escherichia coli was emulsified in oil adjuvant and administered intramuscularly to pregnant cows. Calves born to and reared on vaccinated dams were protected against experimental rotavirus infection at five days old when compared with calves from unvaccinated control cows. Field trials of the vaccine were carried out in 40 commercial herds, in which half the cows in each herd were selected at random for vaccination and half were left unvaccinated. In 31 herds (2641 cows) there was no significant diarrhoea problem (less than 10 per cent morbidity); these herds were excluded from further analysis. The nine remaining herds did experience a calf diarrhoea problem of greater than 10 per cent morbidity, but on four farms the disease was associated with cryptosporidiosis and on a fifth no enteropathogens were detected; these five farms (461 cows) were also excluded from further analysis. Of the remaining four herds, two beef suckler herds (105 cows) had concurrent rotavirus and cryptosporidial infections, and vaccination was associated with a decreased excretion of rotavirus but not with a decreased incidence of diarrhoea. In the other two dairy herds (68 cows) with prevaccination rotavirus problems, there was a significantly decreased incidence of diarrhoea in calves born to vaccinated cows. No natural field challenge of enterotoxigenic E coli was encountered on any of the trial farms.

Animals↗