Immunomodulatory role of thyroid hormones: effect on humoral immune response to Salmonella typhi O antigen

Effect of long term administration of thyroid hormones and the removal of thyroid on humoral antibody response to S. typhi O antigen was studied in male albino rats of HM strain. Humoral antibody response to S. typhi O antigen was enhanced in animals pretreated with T3 or T4 at a dose of 10 micrograms daily for 15 days. Administration of thyroid hormones simultaneously along with antigen, resulted in suppression of antibody response. In thyroidectomized animals, the antibody titer to S. typhi O antigen was decreased; this decrease in antibody titer was restored to normal level following hormone supplementation. Thyroidectomy significantly depressed TLC as well. Total leucocyte count and absolute lymphocyte count were increased following hormone treatment. Present findings, thus show the lymphoproliferative response of thyroid hormones and their effect on antibody response suggesting the immunomodulatory role of thyroid hormones.     

Soluble plasma antigen in experimental Salmonella typhimurium infection in mice

Abstract To detect and characterize Salmonella antigen in blood, outbred CF-1 female mice were inoculated intraperitoneally with S. typhimurium LT-2 and blood was assayed by ELISA for Salmonella common structural antigen. Plasma antigen was detectable early in the course of infection and increased in quantity later in the course of illness when animals showed high grade bacteremia and high counts of splenic bacteria. Antigen was associated with a cell-free plasma fraction of blood, passed through filters with cut-offs of 0.2 μ and molecular mass of 1000 kDa, and was enhanced in detectability after heating to 100°C for 15 min. Antigen was concentrated by diluting plasma 1:4 in 0.1 M EDTA, heating to 100°C, and concentrating the supernate with an ultrafiltration membrane with a molecular mass cut-off of 15 kDa. By gel filtration, antigen was associated with a peak at about molecular mass 300 kDa in heated plasma and a peak at about 380 kDa in unheated plasma. These results indicate that murine typhoid infection results in circulating soluble plasma antigen, which is heat-stable with a molecular mass of approximately 300 kDa.     

The role of M cells in Salmonella infection.

Intestinal M cells, the specialised antigen-sampling cells of the mucosal immune system, are exploited by Salmonella and other pathogens as a route of invasion. Salmonella entry into M cells and colonisation of Peyer's patches involve mechanisms critical for infection of cultured cells as well as factors not accurately modelled in vitro.     

Characterisation of the Salmonella O:8 antigen in the O-chain of the lipopolysaccharide produced by Salmonella virginia O:8.

The antigenic O-polysaccharide of the lipopolysaccharide produced by Salmonella virginia (O:8), analyzed by methylation, partial acid hydrolysis, and one- and two-dimensional nuclear magnetic resonance methods, was found to be a polymer of a repeating pentasaccharide unit composed of D-mannose, D-galactose, L-rhamnose, D-abequose, and O-acetyl (2:1:1:1:1.3) and having the following structure: [formula; see text] The disaccharide structure alpha-D-Abep-(1----3)-L-Rhap was identified as the Salmonella O:8 antigenic factor epitope, since the removal of alpha-D-Abep residues from the O-polysaccharide left a residual tetrasaccharide repeating unit backbone that did not show reaction with Salmonella type O:8 factor antiserum.     

Structural and immunochemical studies of the lipopolysaccharides of Salmonella strains with both antigen O4 and antigen O9.

Two Salmonella hybrid strains, SL5313 (Salmonella typhimurium with a D.rfb+ gene cluster) and SL5396 (S. enteritidis with a B.rfb+ gene cluster), each expressing both O-antigen 4 (of serogroup B) and O-antigen 9 (of serogroup D) were studied by immunofluorescence using a mixture of O4-specific mouse monoclonal and O9-specific rabbit polyclonal antibodies. Bound antibodies, detected by anti-mouse antibody labelled with fluorescein isothiocyanate and anti-rabbit antibody labelled with tetramethylrhodamine isothiocyanate showed that more than 98% of the bacteria expressed both the O4 and O9 epitopes. Phenol-water-extracted lipopolysaccharide from batch-grown cultures subjected to sugar and methylation analyses by gas-liquid chromatography and mass spectrometry were shown to contain abequose (of the O4 epitope) and tyvelose (of the O9 epitope) in ratios of 1:1.5 and 1:2.5 for SL5313 and SL5396, respectively. Isolated polysaccharide chains, obtained by weak-acid hydrolysis of the lipopolysaccharides, were found to contain both O4 and O9 specificities in the same molecule, since polysaccharide bound to O4 antibody attached to a solid-phase-adsorbed O9-specific antibody and vice versa. This demonstrates that in strains SL5313 and SL5396 O chains containing both O4 repeating units (from S. typhimurium) and O9 units (from S. enteritidis) are present.     

Solid-phase method of immunoradiometric determination of the O antigen of Salmonella typhi

The solid-phase variant of radioimmunoassay for the determination of S. typhi O-antigen has been developed. The sensitivity of this method is 0.1 microgram/ml of the antigen in the blood serum of patients. The study of a number of blood serum samples collected from patients with typhoid fever has confirmed the possibility of using this method in clinical practice.     

Plural infection by Salmonella O7 group that hospital infection was doubted]

In Aug, 2002 (heisei 14), a 74-year-old male inpatient had been complaining of fever and diarrhea. A feces culture test was done and a few colonies were discovered and were suspected to be Salmonella O7 and were later confirmed to be as such. A further investigation and interviewing of patients was undertaken. As a result we suspected an internal infection, and did feces culture tests with 7 out of 15 inpatients who had recently had a stomachache or diarrhea and were able to be tested, and 2 discharged patients. Salmonella O7 was detected by direct fulguration in 4 of them and by enrichment in 2, for a total of 6 out of 9 patients. We considered the source to be food poisoning originating in hospital meals and in adherence to the Food Hygiene Law, turned to the proper authorities, which was the Nagaoka Board of Health, for administrative guidance. To search for the cause of this infection, environmental inspections of the patients' rooms and hospital kitchen were undertaken. Further interviews with the patients were also done but they cleared neither the infection source nor the infection route. Even without a genic test, the biotypes were all the same as 53525040. This was discovered by an Autoscan 4 (DADE BEHRING) and the result gave a strong suspicion of an internal infection. The Nagaoka Board of Health was of the opinion that there was a low possibility of the hospital meals being a source of the infection. The reasons were because the diarrhea did not present at the same time among all the patients, there were a distinct few cases of diarrhea among the hospital meal fed patients, and there were no contamination factors found by their investigation of the staff or the system for preparing the meals. Three patients were given an antimicrobic and the measures for training and educating the staff, maintaining a clean environment and fighting infection were re-examined. The case was brought to its conclusion after about 40 days.