Vi antigen and microbial adhesion factors. The detection of adhesins in commercial Vi antigen preparations

Enterobacterial Vi-antigen inhibit the Escherichia coli-induced agglutination of red blood cells of guinea pigs and other animals, which indicates that Vi-antigen contains the admixture of adhesion associated with type I pili. The amount of adhesion contained in Vi-antigen can be determined from the degree to which its hemagglutination-inhibiting effect is manifested.     

Studies of pituitary lactogenic hormone. Physicochemical characterization on procine prolactin.

Porcine pituitary lactogenic hormone has been examined by exclusion chromatography, analytical ultracentrifugation, free-boundary electrophoresis, solubility behavior, circular dichroism, and fluorescence spectra. The results have been compared with previous studies of ovine pituitary lactogenic hormone. These two hormones were found to resemble one another very closely by all criteria studied. While the homology between these lactogenic hormones and growth hormones is strongly reflected in the sharing of certain physicochemical properties, a number of distinct structural differences between these two closely related evolutionary lines are now becoming apparent.     

Enterobacteriaceae isolated from iguanid lizards of west-central Texas.

The prevalence of members of the family Enterobacteriaceae in the intestines of seven species of iguanid lizards native to west-central Texas was determined. Of the 67 lizard specimens examined, 48.7% were infected with Salmonella and 9% were infected with Salmonella arizonae. Two lizard species (Sceloporus olivaceus and Crotaphytus collaris) were shown to have a 100% prevalence of Salmonella.     

Adsorption of Vi antigen on human erythrocytes

The accumulation of Vi-antigen in the human body was studied with the use of such characteristic as the specific adsorption capacity of red blood cells. This parameter was shown to depend on the phenotype in the ABO blood group system. In cases of typhoid fever an increase in the adsorption capacity of red blood cells was observed at the acute period of the disease. These changes were particularly manifest in patients belonging to groups O and A. The authors suggest that the adsorption of the antigen on red blood cells has a definite kinetics related to the dynamics of the infectious process.     

Cationization of protein antigens. IV. Increased antigen uptake by antigen-presenting cells

Cationization of BSA generates a molecule that mounts antibody responses of increased magnitude and duration and induces T cell proliferation at concentrations 500 times less than native BSA (nBSA). To explain the alteration in immunogenic properties of this Ag, the uptake of nBSA and cationized BSA (cBSA) by splenic APC has been investigated. T cell proliferation assays were conducted with nBSA and cBSA preparations with varying degrees of substitution. An inverse correlation between the degree of cationization and the amounts of Ag needed for optimal T cell reactivity was observed. To determine whether affinity for APC resulted in an increased uptake of cBSA, splenic APC were incubated with nBSA or cBSA for varying amounts of time. Comparisons were made at each time point between untreated Ag-pulsed APC (Ag uptake) and paraformaldehyde-fixed Ag-pulsed APC (processed Ag). Proliferation of T cells primed with nBSA or cBSA increased in proportion to the amount of time of APC exposure to high concentrations of nBSA, first appearing after a 2-h pulse and peaking at 8 h. Conversely, untreated APC needed only a 30-min cBSA exposure to induce either nBSA- or cBSA-primed T cell proliferation, indicating a rapid uptake of cBSA. Comparisons with proliferation induced by paraformaldehyde-fixed cBSA APC indicate that nBSA T cells recognize a lag phase-processed form of cBSA, whereas a majority of cBSA T cells recognize either a rapidly processed form of cBSA, or a membrane-processed cBSA molecule without a classical lag phase processing event. When monensin was used as an inhibitor of fluid phase pinocytosis in splenic APC, the presentation of nBSA was inhibited by 85%, but the presentation of cBSA was inhibited by only 20%. These results imply that nBSA enters the cell by fluid phase pinocytosis, whereas cBSA enters by a nonspecific adsorptive mechanism. The different modes of cellular entry for the two molecules, nBSA and cBSA, resulting in a rapid uptake of cBSA, may have important ramifications on T cell activation and immunoregulation.     

Biochemical characteristics and identification of Enterobacteriaceae isolated from meats.

The isolation and identification of 2,220 Enterobacteriaceae from meats indicated that Escherichia coli biotype I, Enterobacter agglomerans, and Serratia liquefaciens were the principal types to be differentiated in meats. Citrobacter freundii, Klebsiella pneumoniae, Enterobacter cloacae, and Enterobacter hafniae were also commonly identified. Identification of isolates by the Encise II (Roche Diagnostics Inc., Nutley, N.J.) and Minitek (BBL Microbiology Systems, Cockeysville, Md.) coding systems gave similar results with only 255 (11.5%) discrepancies in identity, but both systems required large numbers of supplementary tests for identification of the isolates. Not only the distribution of Enterobacteriaceae types isolated from meats but also some of the biochemical reactions of the isolates differed from those of clinical isolates. The Minitek technique is recommended because of its versatility. However, with the addition of cellobiose and salicin disks and the inclusion of methyl red to the Minitek test and the use of the Voges-Proskauer test and gas production in EC medium at elevated temperature as standard tests, the identification of these Enterobacteriaceae from meats would be greatly facilitated. The inclusion of the motility test, for example, using nitrate motility agar, would also be of value to Enterobacteriaceae identification.