The antimicrobial action of the xanthine oxidase-xanthine system on the causative agent of cholera

As revealed in experiments on V. cholerae, the enzymatic link xanthine oxidase-xanthine produces a vibriostatic effect at the concentration of xanthine oxidase equal to 0.0125 g/l and a vibriocidal effect at the concentration of xanthine oxidase equal to 0.025 g/l in a medium with pH 7.5-7.6. In the presence of protein the antivibrionic activity of the xanthine oxidase link is decreased. The introduction of bivalent iron into the enzymatic link xanthine oxidase-xanthine enhances its vibriocidal action on V. cholerae.     

Immunotropic properties of the causative agent of viral hepatitis C

In this review the immunomodulating properties of the causative agent of viral hepatitis C are characterized on the basis of experimental data, obtained by Russian and foreign researchers during recent 3-5 years. The short characterization of the causative agent is presented and a number of adaptation mechanisms making it possible for hepatitis C virus to resist the action of the immune protective system of the host are considered. The role of individual protein products of the virus in the immunopathogenesis of the disease and the mechanisms of their action on the molecular level are discussed in detail on the basis of the results of mouse and in vitro experiments.     

Antigenic properties of the electrophoretic fractions of the causative agent of melioidosis

Antisera to the antigens of 5 fractions, isolated as the result of the separation of P. pseudomallei aqueous saline extract by continuous electrophoresis in the vertical block of granulated gel, have been obtained. Immunoelectrophoresis with the use of P. pseudomallei aqueous saline extract has revealed that antisera to electrophoretic fractions contain antibodies mainly to the antigens of the corresponding fractions, which shows that this technique ensures the effective separation of P. pseudomallei biopolymers by their electrophoretic motility and molecular weight. These antisera differ in their species specificity. Thus, antisera to antigens with anode motility have been found to contain antibodies mainly to P. pseudomallei antigens and antisera to electroneutral antigens or to those with cathode motility, to P. pseudomallei and P. mallei antigens.     

Adenylate cyclase of the causative agent of plague: its purification and properties

Three forms of adenylate cyclase have been detected in Y. pestis: membrane-bound, cytoplasmic and extracellular. Extracellular adenylate cyclase has been purified so as to achieve a homogeneous state, and some of its physicochemical parameters have been investigated. In the process of purification the initial preparation of this enzyme has been subjected to heating at 100 degrees C for 15 minutes, fractionation with ammonium sulfate, and gel filtration on Sephadex G-100. The homogeneity of adenylate cyclase has been confirmed by electrophoresis in 7.5% polyacrylamide gel and precipitation by the plague agglutinating serum. The enzyme has been found to have a molecular weight of 30,000 daltons and to show the optimum activity at pH 7.0-7.2 and at a temperature between 37 and 40 degrees C. Monospecific rabbit serum to the homogeneous preparation of adenylate cyclase has been obtained.     

The leading routes and factors in the transmission of the causative agent of campylobacteriosis under current conditions]

Epidemiological investigations carried out at the foci of Campylobacter infection in Moscow and the Moscow region in 1987-1990 demonstrated that Campylobacter infection was recently registered as sporadic cases in a few foci. The alimentary route of the transmission of this infection was the main factor of its spread. A high role of everyday contacts in the spread of this infection was noted. The possibility for outbreaks and sporadic cases of Campylobacter infection to be masked by very frequently occurring associations of these bacteria is discussed.     

Capsule formation in the causative agent of glanders

Electron-microscopic and electron-cytochemical method were used to indicate the capability of Pseudomonas mallei (str. N 10230) to produce extracellular slime during the agent growth on the meat-peptone agar. In case of guinea pigs infection the agent forms a capsule that defends the pathogen from phagocytosis.     

Heme catabolism in the causative agent of anthrax

A challenge common to all bacterial pathogens is to acquire nutrients from hostile host environments. Iron is an important cofactor required for essential cellular processes such as DNA repair, energy production and redox balance. Within a mammalian host, most iron is sequestered within heme, which in turn is predominantly bound by hemoglobin. While little is understood about the mechanisms by which bacterial hemophores attain heme from host‐hemoglobin, even less is known about intracellular heme processing. Bacillus anthracis, the causative agent of anthrax, displays a remarkable ability to grow in mammalian hosts. Hypothesizing this pathogen harbors robust ways to catabolize heme, we characterize two new intracellular heme‐binding proteins that are distinct from the previously described IsdG heme monooxygenase. The first of these, HmoA, binds and degrades heme, is necessary for heme detoxification and facilitates growth on heme iron sources. The second protein, HmoB, binds and degrades heme too, but is not necessary for heme utilization or virulence. The loss of both HmoA and IsdG renders B. anthracis incapable of causing anthrax disease. The additional loss of HmoB in this background increases clearance of bacilli in lungs, which is consistent with this protein being important for survival in alveolar macrophages.     

Protein phosphorylation in the causative agent of plague

The phenomenon of the reversible phosphorylation of proteins has been discovered in Y. pestis cells. Eight proteins with a molecular weight of 30-80 kilodaltons have been found capable of phosphorylation. The intensity of phosphorylation has been found to be influenced by the temperature of cultivation and the composition of the incubation medium. This newly found phenomenon of the chemical modification of proteins is supposed to play a certain role in the organization of rapid responses of the cell to changes in the environment.     

The properties of the extracellular alkaline phosphatase of the causative agent of melioidosis]

After growing P. pseudomallei VPA on solid medium extracellular alkaline phosphatase with a molecular weight of 93,000 AMU was isolated, and practically purified from the extract of this medium by precipitation with ammonium sulfate, subsequent gel chromatography and concentration on membrane filters. The optimum conditions for enzymatic reaction were found to be pH 9.0 and a temperature of 50 degrees C. The enzyme was resistant to freezing and to heating at a temperature of up 60 degrees C for 30 minutes, as well as to the action of pH 3.0-10.5, but became completely inactivated after heating at 90 degrees C for 10 minutes and incubation at pH 2.0 for 20 hours.