Biomedical subjects

A Guidry

Publications and source records attributed to A Guidry.

7 recordsLinked to original sources

PubMed2000

Prevalence of capsular polysaccharide (CP) types of Staphylococcus aureus isolated from bovine mastitic milk and protection of S. aureus infection in mice with CP vaccine.

To determine the prevalence of capsular polysaccharide (CP) types of Staphylococcus aureus isolated from bovine mastitic milk in Korea, the protective effect of the conjugates, composed of microencapsulated S. aureus clinical isolate type 8 CP bound to Pseudomonas aeruginosa exotoxin A (ETA) was evaluated in mice. Of 107 S. aureus isolates, serotype 5 and 8 accounted for only 26 or 24.2%. When serotype 336 antiserum was employed, fifty of the remaining 81 isolates were typed as 336, 26 reacted with two serotypes, and 5 were nontypeable. Mice challenged with the same strain used for immunization had fewer S. aureus cells in their kidneys than mice challenged with the heterologous strain. But the magnitudes of difference on bacterial clearance were similar in both groups, indicating that the significance of this result remains to be determined. Mice immunized with the conjugate elicited an antibody response 3 days post injection, which persisted for 13 days of the observation period after second injection in some mice. The mice immunized with the CP8-ETA conjugates developed antibodies significantly higher than those immunized with CP-Freund's adjuvant or PBS. In in vivo bacterial challenge experiment, the survival rate of mice immunized with CPS-ETA conjugate was significantly higher than that of mice immunized with PBS. It was suggested that CP8-ETA vaccine had a potential to protect mice against experimental S. aureus bacteremia.

Animals↗

PubMed1999

Hyperimmune bovine colostrum specific for recombinant Cryptosporidium parvum antigen confers partial protection against cryptosporidiosis in immunosuppressed adult mice.

Preparturient cows were immunized three times over a six-week period with recombinant plasmid DNA encoding the Cryptosporidium parvum CP15/60 antigen by injecting the DNA in the mammary gland. Serum was collected at each immunization and first colostrum was collected after parturition; all were assayed for Cryptosporidium-specific antibodies (Ab). A serological response to C. parvum sporozoite and oocyst antigen was detected in cows immunized with pCP15/60 plasmid DNA. Colostrum from these cows, unlike colostrum from normal controls, contained Ab specific for C. parvum sporozoites and oocysts as indicated by immunofluorescence Ab (IFA) staining. Colostrum was also tested for conferring passive immunity against C. parvum infection by oral administration to immunosuppressed adult inbred mice. Immune colostrum and control colostrum were administered to separate groups of dexamethasone (DEX)-treated adult C57BL/6NCr mice beginning 12 h before and at 12 h intervals for 3 days after oral C. parvum oocyst infection. Cryptosporidium development was assayed in ilea of immune- and control-colostrum-treated mice 96 h postinfection by semiquantitative PCR. Mice receiving immune colostrum showed partial protection (about 50% reduction) against intestinal C. parvum development compared to mice receiving control colostrum. This protection was evident at a challenge dose of 10(3) C. parvum oocysts per mouse; no differences were noted in parasite development between groups receiving immune or control colostrum and infected with 10(4) oocysts. This study showed that serum and colostrum Ab response to C. parvum can be elicited in preparturient cows by direct injection of recombinant pCP15/60 plasmid DNA and that passive protection against cryptosporidiosis can be obtained by treating immunosuppressed mice with immune colostrum before and after C. parvum infection.

Animals↗

PubMed1998

Serotyping scheme for Staphylococcus aureus isolated from cows with mastitis.

OBJECTIVE: To identify the Staphylococcus aureus capsular serotypes that are not typable, using capsular serotypes 5 and 8, which are currently used to type S aureus isolated from cows with mastitis. SAMPLE POPULATION: Milk samples (n = 273) from cows with mastitis in 178 dairy herds in California, Wisconsin, Michigan, Texas, and New York that were collected by state diagnostic laboratories and S aureus-positive milk samples collected by Veterinary Health Services in the United Kingdom (15), France (22), The Netherlands (36), and Germany (21). PROCEDURE: Capsular serotyping of coded isolates was performed by use of direct cell agglutination and immunoprecipitation of cell extracts with antisera specific for capsular types 5 and 8 and a newly developed S aureus serotyping antiserum 336. RESULTS: In the United States, S aureus capsular types 5 and 8 accounted for 18 and 23% of the isolates, respectively, and type 336 accounted for 59%. Percentage of capsular serotypes in European samples were as follows: type 5 = 34%, type 8 = 34%, type 336 = 30%, and nontypable = 2%. CONCLUSIONS: Serotypes 5 and 8 accounted for only 41% of S aureus isolates from US milk samples, but accounted for 70% of isolates from European milk samples. Addition of the newly developed serotyping antiserum 336 to the typing scheme accounted for 100% of US samples and 98% of European samples and will enable development of a more comprehensive S aureus vaccine.

Agglutination Tests↗

PubMed1997

Prevalence of capsular serotypes among Staphylococcus aureus isolates from cows with mastitis in the United States.

Development of an appropriate Staphylococcus aureus vaccine for bovine mastitis has eluded researchers for decades. The ability of S. aureus to form a protective exopolysaccharide capsule has posed a major obstacle because of the multiple serotypes and the poor immune response elicited by exopolysaccharides. This study characterized S. aureus serotypes isolated from cases of bovine mastitis obtained from veterinary diagnostic laboratories that service 44% of the dairy cattle in the United States. Major milk producing areas of the northeast, north central, Pacific coast and southwest were proportionately represented. Sub-samples of mastitic milk that contained S. aureus were frozen and sent to our laboratory for strain serotyping. The only other regional serotyping of S. aureus from bovine mastitis to date was done in France. The primary serotypes found were types 5 (51%) and 8 (18%) and 31% were non-typeable. In the current study, serotype 5 accounted for 18% of the isolates and serotype 8 for 23%. More importantly 59% of the isolates were not typeable with either type 5 or 8 antisera. These data indicate that S. aureus vaccines employing serotypes 5 and 8 would only be marginally effective in the United States. These data also suggest that development of a S. aureus vaccine for bovine mastitis should take into account regional variation in S. aureus serotypes.

Animals↗

PubMed1996

Role of milk fractions, serum, and divalent cations in protection of mammary epithelial cells of cows against damage by Staphylococcus aureus toxins.

OBJECTIVE: To determine the effect of milk and blood serum constituents on cytotoxicity of Staphylococcus aureus on mammary epithelial cells. DESIGN: In vitro incubation of cells with cytotoxic agents and milk and serum constituents. SAMPLE POPULATION: Mammary cells, milk, and blood obtained from 3 cows. PROCEDURE: Staphylococcal alpha-toxin and culture supernatants from S aureus M60 and an alpha-toxin-negative mutant of M60 were incubated with bovine mammary epithelial cells in the presence of milk fractions, serum, and divalent cations. Propidium iodide fluorescence was used as a measure of cell damage. RESULTS: Skim milk and milk whey inhibited S aureus cytotoxic agents. Skim milk protected against alpha-toxin damage to a greater extent than milk whey. Serum from an adult animal was more protective than was fetal serum. Milk fat and serum albumin had no protective effect. Divalent calcium and Mg2+ were more effective inhibitors of mammary epithelial cell damage caused by alpha-toxin than of damage attributable to M60 culture supernatant. Divalent calcium and Mg2+ at concentrations similar to those of free Ca2+ and Mg2+ in normal bovine milk decreased cytotoxic damage attributable to alpha-toxin. However, concentrations similar to those of total Ca2+ and Mg2+ in normal milk were required to decrease cell damage caused by M60 culture supernatant. The alpha-toxin-negative mutant was less cytotoxic than the M60 parent strain. CONCLUSIONS: Casein, as well as Ca2+ and Mg2+ in bovine milk, inhibit the cytotoxic effect of S aureus on mammary epithelial cells.

Animals↗

PubMed1990

Immunotherapeutic efficacy of bovine colostral immunoglobulins from a hyperimmunized cow against cryptosporidiosis in neonatal mice.

Infection with Cryptosporidium parvum, a ubiquitous protozoan parasite of virtually all mammals, can cause mild to severe diarrhea in immunocompetent hosts and life-threatening diarrhea in immunocompromised hosts. Passive immunotherapy of experimentally infected animals and naturally infected humans with hyperimmune bovine colostrum has been reported to be efficacious, whereas chemotherapy has not. In this study, the efficacy of specific immunoglobulin isotypes purified from bovine colostrum from a cow hyperimmunized with Cryptosporidium parvum was assessed in neonatal BALB/c mice. Mice were orally infected with oocysts and treated with whole whey immunoglobulin G1 (IgG1), IgG2, IgA, or IgM at six intervals from 22 to 66 h postinfection. In histologic sections of intestine examined at 72 h postinfection, the reduction in number of intestinal stages in treated mice versus untreated controls was very highly significant (P less than 0.0001). The greatest reduction in parasite number was found in mice treated with IgG1, IgA, or whey.

Animals↗

PubMed1990

Cryptosporidium parvum (Apicomplexa: Cryptosporidiidae) oocyst and sporozoite antigens recognized by bovine colostral antibodies.

Colostral whey from seven hyperimmunized and two control cows (hyperimmune bovine colostrum) was examined by Western immunoblotting for the presence of antibody against oocysts and sporozoites of Cryptosporidium parvum, using rabbit anti-bovine immunoglobulin A (IgA), IgG1, IgG2, and IgM antibodies, followed by a horseradish peroxidase goat anti-rabbit polyvalent antibody. Although considerable variation was found in binding activity between cows on different immunization protocols, IgA and IgG1 in whey recognized a greater variety of C. parvum antigens than did IgG2 and IgM. A band at 9 to 10 kilodaltons appeared unique in that it was recognized only by IgA.

Animals↗