Our recent study has provided that the in vitro SEC-induced proliferation of bovine T cells is preceded by a period of a non-proliferative immunoregulation of T cells that may be associated with cytokine production regulated by type 1 or type 2 T cells. Inversion of CD4+:CD8+ T cell ratio and induction of CD8+T cells with immunoregulatory activity could increase the probability of intracellular survival of Staphylococcus aureus (S. aureus). The increase of activated CD8+(ACT2+ BoCD8+) T cells in cows with mastitis caused by S. aureus may be associated with immune-regulatory function in the bovine mammary gland. The difference and similarity between bovine activated CD8+ T cells (CD8+ CD26+)and well-established human CD4+ CD25+ T regulatory (Tr)cells may help to reveal their unique immune regulatory system in the host infected with S. aureus.
Animals ; Cattle ; Cell Proliferation ; Female ; Lymphocyte Activation/immunology ; Mastitis, Bovine/*immunology/microbiology ; Staphylococcal Infections/immunology/*veterinary ; Staphylococcus/*immunology ; *Superantigens ; T-Lymphocytes/*immunology

One hundred seven isolates of Staphylococcus aureus from bovine mastitis were investigated for colony morphology in serum-soft agar (SSA), autoagglutination in salt, and capsular serotype. Capsular polysaccharide (CP) was purified and quantified from the extracts of clinical isolates. Overall, 89 isolates (83.2%) were diffuse in the SSA, without any difference in the proportion of diffuse colony between type 5 and type 8 strains. Some strains exhibited compact colonies in the SSA and expressed CP as determined by an enzyme-linked immunosorbent assay, indicating that compact morphology does not exclude encapsulation. The majority of the strains (11/12) showed autoagglutination in the salt aggregation test. The serotype 336 accounted for 46.7% of the isolates followed by serotype 5 (12.1%) and serotype 8 (12.1%). Particularly, twenty-six (24.3%) isolates reacted with two serotypes; 7 for type 8/336 and 19 for type 5/336. Five isolates (4.7%) were nontypeable with monoclonal antibodies specific for CP serotype 5, 8, or 336. The CP concentration in culture supernatants varied with the serotypes, and the total amount of CP produced by cells grown in a liquid medium was much less than that produced by cells grown on a solid medium. The Western blotting indicated that the CP bands of S. aureus serotype 5 and 8 were ranged in the molecular mass of 58-84 kilodalton (kDa), with additional bands in the region of approximately >or= 48 or Agglutination Tests ; Animals ; Bacterial Vaccines/administration & dosage ; Cattle ; Cattle Diseases/immunology/microbiology ; Female ; Mastitis, Bovine/*microbiology ; Polysaccharides, Bacterial/*classification/isolation & purification ; Serotyping/methods/veterinary ; Staphylococcal Infections/immunology/*veterinary ; Staphylococcus aureus/*classification/*immunology/isolation & purification

We previously demonstrated that stimulation of bovine peripheral blood mononuclear cells (PBMCs) with staphylococcal enterotoxin C (SEC), led to an inversion of the CD4(+):CD8(+) T cell ratio and generation of an atypical CD8(+) T cell subpopulation expressing CD26. In the present study, we examined T cell apoptosis and proliferation profiles of PBMC subpopulations in cultures stimulated with SEC. Unlike when stimulated with concanavalin A, nucleic acid synthesis in bovine PBMC cultures stimulated with SEC was low during the first four days but increased greatly on day 5. In contrast, nucleic acid synthesis in human PBMC cultures stimulated with SEC increased continuously. To investigate the mechanism of delayed bovine T cell proliferation, various cell phenotypes were monitored. The inversion of the bovine CD4(+):CD8(+) T cell ratio in PBMC cultures stimulated by SEC was associated with higher proliferation and lower apoptosis of CD8(+) T cells compared to CD4(+) T cells. The mRNA levels for interleukin (IL)-4 and IL-13 were sustained over 4 days but IL-12 mRNA levels dropped to background on day 2. These data suggest that SEC induces a prolonged Th-2- biased microenvironment, and together with the inversion of the bovine CD4(+):CD8(+) T cell ratios in bovine PBMC cultures with SEC, may in part explain the inability of the mammary immune system to establish an effective response to Staphylococcus aureus infections.
Animals ; Apoptosis/drug effects/immunology ; CD4-CD8 Ratio/veterinary ; CD4-Positive T-Lymphocytes/drug effects/*immunology/microbiology ; CD8-Positive T-Lymphocytes/drug effects/*immunology/microbiology ; Cattle ; Concanavalin A/pharmacology ; Cytokines/genetics/immunology ; Enterotoxins/*pharmacology ; Female ; Lymphocyte Activation/drug effects ; Mastitis, Bovine/immunology/*microbiology ; Reverse Transcriptase Polymerase Chain Reaction/veterinary ; Staphylococcal Infections/immunology/microbiology/*veterinary ; Staphylococcus aureus/*immunology

Staphylococcus (S.) aureus is a common infectious agent of bovine chronic mastitis, a disease that is difficult to eradicate. The abilities of Staphylococci to be internalized and form a biofilm can contribute to host immunological defence evasion that subsequently impairs antimicrobial therapy. The invasive capability of six S. aureus field isolates with different biofilm-forming profiles was compared in vitro using a bovine mammary epithelial cell line. This was further confirmed in primary cell cultures using fluorescent rRNA probes against S. aureus. The results suggest that S. aureus invasion levels are not related to biofilm formation.
Animals ; *Biofilms ; Cattle ; Cell Line ; Colony Count, Microbial/veterinary ; Epithelial Cells/microbiology ; Female ; In Situ Hybridization, Fluorescence ; Mastitis, Bovine/*microbiology ; Portugal ; Staphylococcal Infections/*veterinary ; Staphylococcus aureus/classification/genetics/immunology/*physiology ; Virulence Factors/i

In the present study, Staphylococcus (S.) hyicus strains isolated in Russia (n = 23) and Germany (n = 17) were investigated for the prevalence of the previously described genes sheta and shetb. Sheta was detected in 16 S. hyicus strains. Sheta-positive strains were mainly found among strains isolated from exudative epidermitis, and frequently together with the exfoliative toxin-encoding genes exhD and exhC. Partial sequencing of sheta in a single S. hyicus strain revealed an almost complete match with the sheta sequence obtained from GenBank. None of the S. hyicus strains displayed a positive reaction with the shetb-specific oligonucleotide primer used in the present study. According to the present results, the exotoxin encoding gene sheta seems to be distributed among S. hyicus strains in Russia and Germany. The toxigenic potential of this exotoxin, which does not have the classical structure of a staphylococcal exfoliative toxin, remains to be elucidated.
Animals ; Cattle ; Cattle Diseases/epidemiology/microbiology ; DNA Primers ; Dog Diseases/epidemiology/microbiology ; Dogs ; Epidermitis, Exudative, of Swine/epidemiology ; Exfoliatins/*genetics/immunology ; Germany ; Pneumonia/epidemiology/veterinary ; Russia ; Staphylococcal Infections/immunology/veterinary ; Staphylococcus aureus/genetics/*pathogenicity ; Swine ; Swine Diseases/epidemiology ; Virulence/*genetics ; Virulence Factors/genetics/immunology