Sensitivity of Borrelia genospecies to serum complement from different animals and human: a host-pathogen relationship

Different Borrelia species and serotypes were tested for their sensitivity to serum complement from various animals and human. Complement-mediated Borrelia killing in cattle, European bison and deer was higher irrespective of the Borrelia species whereas in other animals and human it was intermediate and Borrelia species-dependent. Activation of the alternative complement pathway by particular Borrelia strain was in correlation with its sensitivity or resistance. These results support the incompetent reservoir nature of cattle, European bison, red, roe and fallow deer, at the same time present the probable reservoir nature of mouflon, dog, wolf, cat and lynx. In short, this study reviews Borrelia-host relationship and its relevance in reservoir competence nature of animals.     

Structure of compstatin in complex with complement component C3c reveals a new mechanism of complement inhibition

Undesired complement activation is a major cause of tissue injury in various pathological conditions and contributes to several immune complex diseases. Compstatin, a 13-residue peptide, is an effective inhibitor of the activation of complement component C3 and thus blocks a central and crucial step in the complement cascade. The precise binding site on C3, the structure in the bound form, and the exact mode of action of compstatin are unknown. Here we present the crystal structure of compstatin in complex with C3c, a major proteolytic fragment of C3. The structure reveals that the compstatin-binding site is formed by the macroglobulin (MG) domains 4 and 5. This binding site is part of the structurally stable MG-ring formed by domains MG 1-6 and is far away from any other known binding site on C3. Compstatin does not alter the conformation of C3c, whereas compstatin itself undergoes a large conformational change upon binding. We propose a model in which compstatin sterically hinders the access of the substrate C3 to the convertase complexes, thus blocking complement activation and amplification. These insights are instrumental for further development of compstatin as a potential therapeutic.     

Chlorlincocin kinetics in animals with a disordered hormonal balance]

Distribution of chlorlincomycin in intact rats and animals with an impaired hormonal balance was studied. Estradiol or hydrocortizon acetate were administered repeatedly to the animals in large doses with a purpose of inducing pathological conditions. Chlorlincomycin was administered intravenously for 11 days in a dose of 15 mg/kg. The antibiotic levels in the blood serum and organs of the rats were determined at various intervals after the drug administration. The hormones induced changes in the sexual cycle. Hydrocortizon acetate markedly changed the animal weight and the weight coefficient of the internal organs. The kinetics of chlorlincomycin in the animals with hormonal impairments induced by estradiol or hydrocortizon acetate changed insufficiently as compared to that in the intact rats. Individual fluctuations in the antibiotic distribution was observed in the animals treated with hydrocortizon acetate. The levels of chlorlincomycin in the blood of the weakest animals were higher. No cumulation of the drug was noted.     

Variegation associated with lacZ in transgenic animals: a warning note

Transgenic Research -