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S D Acres

Publications and source records attributed to S D Acres.

At least 19 recordsLinked to original sources
PubMed1989

Presence of bacterial glycocalyx and fimbriae on Pasteurella haemolytica in feedlot cattle with pneumonic pasteurellosis.

This investigation was conducted to determine if Pasteurella haemolytica within feedlot cattle affected by pneumonic pasteurellosis express fimbriae (pili) and bacterial glycocalyx. Bacteriological culture of pulmonary tissue from three calves with fibrinous pneumonia resulted in heavy growth of P. haemolytica. Transmission electron microscopy of the lungs showed numerous microcolonies of gram-negative bacteria with morphology typical of Pasteurella haemolytica. The cells within these microcolonies possessed bacterial glycocalyces which stained with ruthenium red. Glycocalyx-encased microcolonies were also present in specimens examined by scanning electron microscopy. Typical P. haemolytica cells were evident in a tracheal specimen and these bacteria had radial glycocalyces consistent with polysaccharide and proteinaceous material condensed on linear structures suggestive of fimbriae. The pathogenetic importance of the bacterial glycocalyx and fimbriae in shipping fever pneumonia has yet to be established but their presence in clinical cases of Pasteurella pneumonia in feedlot cattle further supports a possible role in the initiation and progression of this disease as well as bacterial resistance to antimicrobial agents.

Animals↗
PubMed1988

Electron microscopic examination of cells of Pasteurella haemolytica-A1 in experimentally infected cattle.

Several modern electron microscopy techniques were used to examine Pasteurella haemolytica (biotype A, serotype 1) (strain B122) recovered from experimentally infected cattle and in situ within the lung tissue of experimentally infected cattle. Glycocalyx four to five times thicker than that seen on P. haemolytica grown in vitro was evident on bacterial cells recovered from live infected calves by pulmonary lavage. Fimbriae were also present on cells recovered by lavage. A thick glycocalyx was also seen on P. haemolytica-A1 within the lungs of experimentally infected cattle at necropsy. In summary, cells of P. haemolytica-A1 in experimentally infected cattle have fimbriae and glycocalyx on their cell surfaces and these structures appear to be important in bacterial colonization of the bovine respiratory tract and pathogenesis of shipping fever (Pasteurella) pneumonia.

Animals↗
PubMed1987

Monoclonal antibody passive hemagglutination and capture enzyme-linked immunosorbent assays for direct detection and quantitation of F41 and K99 fimbrial antigens in enterotoxigenic Escherichia coli.

Production of diarrhea in neonatal calves by enterotoxigenic Escherichia coli depends on its ability to attach to the epithelial cells of the intestine via surface adhesins called pili or fimbriae and to secrete enterotoxins. The most important of these fimbriae are designated K99 and F41. We produced and characterized a murine monoclonal antibody specific to F41. This monoclonal antibody and a K99-specific monoclonal antibody were used to develop sensitive and specific passive hemagglutination and capture enzyme-linked immunosorbent assays (ELISAs) for detection and quantitation of F41 and K99 antigens in E. coli cultures and culture supernatants. The capture ELISA systems exhibited excellent sensitivity and specificity, whereas the passive hemagglutination systems appeared to be oversensitive. The ability of the capture ELISAs to detect K99 and F41 fimbrial antigens in fecal specimens from calves was evaluated. Fimbrial antigens were detected in six of six specimens from scouring calves but not in four of four specimens from nonscouring calves.

Animals↗
PubMed1987

Electron microscopic description of glycocalyx and fimbriae on the surface of Pasteurella haemolytica-A1.

Several electron microscopic techniques were used to examine the surface of cells of Pasteurella haemolytica (biotype A, serotype 1) grown in vitro. All methods showed the presence of a very extensive glycocalyx on logarithmic phase (6 h) cells grown in liquid media. The anionic glycocalyx of these cells stained well with ruthenium red, but collapsed during dehydration for electron microscopy unless stabilized with specific antibodies. When the same techniques were used to examine cells in the stationary phase (18 h) the glycocalyx was much reduced. Large numbers of fimbriae were seen on both 6 h and 18 h cells grown in fluid media without shaking. In summary, logarithmic phase cells of P. haemolytica have both fimbriae and extensive anionic glycocalyx at their surface and we suggest that either or both of these structures may be important in the colonization of the bovine respiratory tract and the subsequent pathogenesis of Pasteurella pneumonia.

Animals↗
PubMed1985

Enterotoxigenic Escherichia coli infections in newborn calves: a review.

Diarrhea caused by enterotoxigenic Escherichia coli is an infectious bacterial disease of calves that occurs during the first few days of life. The Escherichia coli that cause the disease possess special attributes of virulence that allow them to colonize the small intestine and produce an enterotoxin that causes hypersecretion of fluid into the intestinal lumen. These enterotoxigenic Escherichia coli are shed into the environment by infected animals in the herd and are ingested by newborn calves soon after birth. There is some natural immunity to enterotoxigenic Escherichia coli; however, it often fails to protect calves born and raised under modern husbandry conditions. Hence, methods have been developed to stimulate protective immunity by vaccination of the dam. The protective antibodies are transferred passively to calves through the colostrum.

Animals↗
PubMed1984

Monoclonal antibody capture enzyme-linked immunosorbent assay for detection of bovine enteric coronavirus.

Monoclonal antibodies reactive with three different viral polypeptides were evaluated singly and in combination as the capture antibody(s) in an enzyme-linked immunosorbent assay system for the detection of bovine enteric coronavirus. Similar levels of sensitivity were found for all combinations tested. A sensitive, highly specific, and reproducible assay for the detection of bovine enteric coronavirus was developed, using a mixture of two of these monoclonal antibodies reactive with antigenic components either external or internal to the virion. These monoclonal antibodies were bound indirectly to 96-well plates via rabbit anti-mouse immunoglobulin. After sample application and incubation, virus was detected by using rabbit anti-coronavirus peroxidase conjugate followed by enzyme substrate and chromagen. Fecal samples from a single herd of cows were screened for the presence of coronavirus by this assay. Five percent of clinically normal cows were found to be shedding coronavirus.

Animals↗
PubMed1984

Morphological examination of cell surface structures of enterotoxigenic strains of Escherichia coli.

The very fine sinuous K99 pili of enterotoxigenic strains of Escherichia coli can be visualized in shadowed and in negatively stained preparations, especially if the amorphous K30 glycocalyx is not produced, but these very delicate structures cannot be directly resolved in sectioned material. The K99 pili can, however, be thickened by the nonspecific accretion of K30 glycocalyx material, during its condensation as a result of dehydration, to the point where it can be resolved in sectioned material. This visualization is enhanced if the accreted and condensed glycocalyx is stained with ruthenium red. Alternatively and additionally, the K99 pilus can be thickened by the specific accretion of monoclonal antibodies so that it is made visible in sectioned material. The condensation of the hydrated K30 antigen glycocalyx of enterotoxigenic strains of Escherichia coli during dehydration can be prevented by stabilization using specific antibodies so that this capsular glycocalyx structure is identified in sectioned material and is seen in its correct distribution and dimensions. These methods allow the identification and visualization of bacterial surface structures, both in vitro and in vivo, and they provide a useful means of assessing the presence and distribution of these structures at all stages of the bacterial disease and a possible means of assessing their roles in the pathogenic process.

Cell Membrane↗
PubMed1984

Prevalence of rotavirus and coronavirus antigens in the feces of normal cows.

The prevalence of rotavirus and coronavirus shedding by adult cows was investigated using capture enzyme-linked immunosorbent assays. Fecal samples from 121 cows in a single herd were tested for the presence of rotavirus and coronavirus, either free or complexed with immunoglobulin. Free rotavirus was not detected in any samples while rotavirus-immunoglobulin complexes were detected in 53 of 121 (44%) samples tested. In contrast, free coronavirus was detected in six (5%) samples and coronavirus-immunoglobulin complexes were detected in 85 (70%) of the samples tested. Thus it appears that subclinical infection of cows by either of these viruses is common, possibly providing a source for infection of the neonate. These assays may therefore provide important information regarding the epidemiology of enteric virus infections and suggest means of improving management to prevent epidemics of neonatal diarrhea.

Animals↗
PubMed1983

The control of acute undifferentiated diarrhea of newborn beef calves.

A management system designed to control diarrhea in newborn beef calves has been outlined. The calving herd is moved from the wintering grounds to previously prepared, comfortable calving grounds. The herd is divided into small subunits for surveillance of calving. The calving areas should be well-bedded, and a natural or artificial windbreak should be provided. All parts of the calving grounds should be readily accessible. Every effort is made to ensure that calves receive a liberal supply of colostrum within hours after birth. Obstetrical assistance is provided as necessary to ensure that all calves are born vigorous. At 24 hours of age, the cow-calf pair is moved out of the calving grounds to the nursery pasture. Diarrheic calves are moved to an isolation area and treated accordingly. The system is successful because the newborn calf is moved from contaminated areas of high population density to areas of lower population density that are less contaminated with the common enteropathogens. Under certain circumstances, the vaccination of the dam in late pregnancy with E. coli K99+ bacterins may be beneficial as an aid to the control of the disease.

Acute Disease↗
PubMed1983

Susceptibility of bovid herpesvirus 1 to antiviral drugs: in vitro versus in vivo efficacy of (E)-5-(2-Bromovinyl)-2'-deoxyuridine.

The relative efficacies of a variety of antiviral drugs against bovid herpesvirus 1 was investigated. (E)-5-(2-Bromovinyl)-2'-deoxyuridine and trifluorothymidine were found to be inhibitory at doses of 0.01 micrograms/ml in in vitro yield reduction and plaque reduction assays. In contrast, acylovir was inactive even at concentrations as high as 1,000 micrograms/ml. Other drugs, including phosphonoformic acid, 9-beta-D-arabinofuranosyladenine, 5-iodo-2-deoxyuridine, and 1-beta-D-arabinofuranosylcytosine were active at concentrations previously shown to inhibit herpes simplex virus. Oral administration of (E)-5-(2-bromovinyl)-2'-deoxyuridine to calves infected with bovid herpesvirus 1 had no effect on the level of virus shedding, clinical signs, or susceptibility to secondary bacterial infection with Pasteurella haemolytica. The reason for this lack of in vivo activity was that sufficient levels of the drug in blood were not achieved by oral administration.

Animals↗
PubMed1983

Protection of calves against fatal enteric colibacillosis by orally administered Escherichia coli K99-specific monoclonal antibody.

A monoclonal antibody (MCA) to enterotoxigenic Escherichia coli K99 antigen agglutinated K99+ enterotoxigenic E. coli strains B44 (O9:K30;K99;F41:H-) and B41 (O101:K99;F41:H-) grown at 37 degrees C but not at 18 degrees C. The MCA, which was characterized as immunoglobulin G1, reacted specifically with K99 antigen in an enzyme-linked immunosorbent assay and precipitated radiolabeled K99 antigen. A total of 45 colostrum-fed and colostrum-deprived calves were used in three separate trials to determine whether the orally administered K99-specific MCA would prevent diarrhea caused by strain B44. Twenty-eight calves were fed 1 ml of mouse ascitic fluid containing K99-specific MCA at 10 h of age and were orally challenged with strain B44 at 12 to 14 h of age. Control calves either received no placebo or were fed 1 ml of mouse ascitic fluid containing fibronectin-specific MCA at 10 h of age. There was no difference in the incidence of diarrhea between the two groups after challenge. However, the severity of diarrhea, as evaluated by the proportion of calves in each group that developed severe dehydration, the degree of clinical dehydration, the degree of clinical depression, the degree of weight loss, and the duration of diarrhea after challenge was significantly reduced in calves that received the K99-specific MCA. The mortality rate was also significantly lower (P less than 0.001) in the treated (29%) than in the control (82%) group. These results suggest that orally administered K99-specific MCA can prevent severe fatal enteric colibacillosis.

Animals↗
PubMed1983

A comparison of histopathological changes in calves associated with K99- and K99+ strains of enterotoxigenic Escherichia coli.

Enterotoxigenic colibacillosis was experimentally produced in four colostrum-deprived calves given 10(10) Escherichia coli strain 210 (serotype 09+:K30+:K99-:F41-:H-) orally and the histopathological changes compared to those seen in colostrum-fed calves infected in an earlier study with strain B44 (serotype 09+:K30+:K99+:F41+:H-). Escherichia coli strain 210 caused diarrhea, atrophic villi with cuboidal epithelium, and focal accumulations of a few neutrophils in the dome villi above Peyer's patches but neither the clinical nor the histopathological changes were as pronounced as with strain B44. The extent and distribution of adherence to the mucosal surface differed between the two strains. Strain B44 adhered as a continuous layer over most of the absorptive epithelial surface of both the jejunum and ileum. Adherence of strain 210 was restricted to the ileum and the bacteria often adhered focally in "clumps" rather than as a continuous layer, especially on the distal half of the villous surface.

Animals↗
PubMed1983

The use of specific antibodies to demonstrate the glycocalyx and spatial relationships of a K99-, F41- enterotoxigenic strain of Escherichia coli colonizing the ileum of colostrum-deprived calves.

Electron microscopy was used to study the interaction between the glycocalyx of enterotoxigenic Escherichia coli strain 210 (09:K30+;K99-;F41-:H-) and the glycocalyx of epithelial cells in then ileum of experimentally infected newborn colostrum-deprived calves. Fixation of tissues in anti-K30 antibody and ruthenium red was used to stabilize the bacterial glycocalyx so that the spatial relationship between the bacteria and the intestinal epithelial cells could be characterized. When strain 210 was grown in vitro and reacted with anti-K30 antibody prior to staining with ruthenium red, the extensive glycocalyx could be clearly visualized surrounding the bacterial cells. By negative staining, an unidentified pilus was also seen. Sections of ileum from infected calves, which were not fixed in antibody nor stained with ruthenium red, revealed attached bacteria which were surrounded by an electron-translucent zone and no visible bacterial glycocalyx. When ruthenium red staining was used, the bacterial glycocalyx partially collapsed during the dehydration steps of fixation, but could be seen as either a fibrous capsule or an electron-dense accretion on the bacterial cell surface. When ileal tissue was reacted for one hour in anti-K30 antibody before staining with ruthenium red, the bacterial glycocalyx was seen as a discrete electron-dense structure up to 1.0microm thick which was in intimate contact with the glycocalyx of the epithelial cells. The importance of the bacterial exopolysaccharide to microcolony formation on the villi could be clearly visualized.

Animals↗
PubMed1982

Use of specific antibody to demonstrate glycocalyx, K99 pili, and the spatial relationships of K99+ enterotoxigenic Escherichia coli in the ileum of colostrum-fed calves.

The attachment of enterotoxigenic Escherichia coli (ETEC) strain B44 (O9:K30:K99:F41:H-) to the ileal epithelium of newborn colostrum-fed calves was studied by electron microscopy. Stabilization of the bacterial glycocalyx (K30) and pili (K99) by fixation of tissue sections in specific antibody and staining with ruthenium red were used so that the bacterial surface structures could be clearly visualized and their spatial relationship to the intestinal brush border defined. When sections of ileum from infected calves were neither fixed in antibody nor stained with ruthenium red, the ETEC cells colonizing the small intestine were separated from each other and from the brush border by an electron-translucent halo; neither the glycocalyx nor the pili could be clearly resolved. When ruthenium red staining was used, the halo was partially filled by a net of electron-dense fibers composed of pili and condensed glycocalyx which extended to the brush border. Tissue sections reacted with anti-K30 antibody before staining with ruthenium red revealed microcolonies of ETEC surrounded by a discrete electron-dense glycocalyx 0.3 to 1.0 micrometers thick and in tight contact with the epithelial cell surface. When ileal tissue was treated with K99 antibody, the K99 pili were visible as discrete fibers extending from the bacterial cell surface through the glycocalyx. We discuss the role of these cell surface components in pathogenic adhesion and in the formation of protected microcolonies at the surface of the infected ileal epithelium.

Adhesiveness↗
PubMed1982

Detection by radioimmunoassay and enzyme-linked immunosorbent assay of coronavirus antibodies in bovine serum and lacteal secretions.

The sensitivity of a radioimmunoassay (RIA), an enzyme-linked immunosorbent assay (ELISA), and a serum neutralization assay (SN) for detecting antibodies to bovine coronavirus in serum and colostrum were compared. Although there proved to be a good correlation among all three assays (r = 0.915 and 0.964 for RIA with SN and ELISA, respectively), RIA and ELISA proved to be at least 10 times more sensitive than neutralization tests. By using these techniques, it was possible to detect a time-dependent decrease in antibody levels in bovine colostrum after parturition. Using ELISA, we demonstrated that 12 of 12 herds in Saskatchewan, and 109 of 110 animals tested, and antibody to bovine coronavirus. There was no elevated antibody response in serum or lacteal secretions of cows vaccinated once or twice with a commercially available modified live rota-coronavirus vaccine. In addition to being more sensitive than SN, ELISA and RIA proved to have other advantages for measuring antibody levels to bovine coronavirus and therefore warrant wider use as tools in diagnostic virology.

Animals↗
PubMed1982

The immunogenicity of K99 antigen in whole cell bacterins of Escherichia coli.

K99 antigen in Escherichia coli whole cell bacterins was immunogenic in rabbits and mice. Mice vaccinated subcutaneously and bled three weeks later had a serum antibody response which was dose dependent. The dose response on dilution of bacterins was shown to be mainly due to dilution of K99 antigen, rather than the reduction in adjuvant or bacterial cell concentration. The procedure appears to be a satisfactory one for immunogenicity testing of bacterins containing K99 antigen.

Adjuvants, Immunologic↗