Evaluation of glycoprotein Ib expression on feline platelets.

OBJECTIVE: To determine whether platelets obtained from cats expressed glycoprotein Ib (GPIb). SAMPLE POPULATION: Platelets obtained from 11 specific-pathogen-free cats. PROCEDURE: Platelets were analyzed by use of immunofluorescence microscopy, flow cytometry, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western immunoblot analysis, and immunoprecipitation. RESULTS: Immunofluorescence microscopy and flow cytometry revealed the protein on the surface of feline platelets. Biochemical studies (western immunoblot analysis and immunoprecipitation) revealed a 140-kd membrane glycoprotein. Additional biochemical studies revealed that feline GPIb was sensitive to proteolysis, because platelet cytoskeletons prepared with low concentrations of a calpain inhibitor (ie, leupeptin; 100 microg/ml) had substantial proteolysis, and there was an association of protein fragments with the actin cytoskeleton. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results indicate that feline platelets express a 140-kd membrane protein that is recognized by monoclonal antibodies developed against GPIb. Application of standardized ELISA to quantitate glycocalicin, the water-soluble fragment of GPIb, may provide important information on the production of microvesicles, increased platelet turnover, and abnormal proteolysis.

Development and evaluation of an extra chromosomal DNA-based PCR test for diagnosing bovine babesiosis.

Subclinical infections of bovine babesiosis, caused primarily by Babesia bigemina or Babesia bovis are a challenge to current diagnostic methods. In this study, the development and evaluation of a PCR test for sensitive and specific detection of B. bigemina or B. bovis is described. The target selected for amplification is part of the apocytochrome b gene, conserved in both Babesia spp. and located on the linear approximately 6.0 kb extra chromosomal DNA. The test was evaluated to detect the parasites over a period of 5 (B. bigemina) and 10 months (B. bovis) post infection in experimentally infected cattle. Analysis of DNA extracted from blood samples drawn from the experimental cattle in a blind study revealed an overall sensitivity of 85 and 64% for B. bovis and B. bigemina respectively, while the specificity was 97% for B. bovis and 91% for B. bigemina. The test results were compared with the recently developed ribosomal DNA-based polymerase chain reaction (PCR) test and to the complement fixation test for both Babesia spp. The extra chromosomal DNA-based test was 20% more sensitive than that of ribosomal DNA-based tests. This test may be a more desirable alternative to the currently used, complement fixation test.

Intraerythrocytic inclusions associated with iridoviral infection in a fer de lance (Bothrops moojeni) snake.

Intraerythrocytic inclusions associated with infection by an iridovirus were observed in a fer de lance (Bothrops moojeni) snake that was being evaluated for the presence of renal carcinoma. The erythrocytes contained two types of inclusions, one viral and one crystalline, usually concomitantly. The snake was markedly anemic and exhibited a marked regenerative response. Ultrastructural analysis identified the virus to be an iridovirus consistent with snake erythrocyte virus and the crystalline structures to be of a different nature than hemoglobin.

Isolation of Mycoplasma felis from a serval (Felis serval) with severe respiratory disease.

We report cytologic observations and isolation of Mycoplasma felis in September 1992 from the lower respiratory tract of a 3-week-old captive serval (Felis serval) cub with pneumonia, in Florida (USA). Septic, neutrophilic inflammation with a large, monomorphic population of unique, pleomorphic, intracellular and extracellular rods was diagnosed from a transtracheal wash. Mycoplasma felis was the only bacterium isolated in significant numbers from the transtracheal wash.

Induction of acyclovir-resistant mutants of herpes simplex virus type I in athymic nude mice.

Induction of acyclovir resistance was studied in the immune compromised host by multiple passage of plaque-purified herpes simplex type I strains in athymic nude mice receiving suboptimal antiviral therapy. Mice infected with a highly pathogenic clinical isolate rapidly developed infections that were resistant to therapy. Viruses isolated from these mice had decreased in-vitro sensitivities to acyclovir, as well as altered characteristics when assayed by [125I]plaque autoradiography. In contrast, less virulent laboratory strains, or a genetically stable clinical isolate, showed no indication of mutation to resistance after extended passage in this mouse model. Highly pathogenic viruses may increase the probability of mutation to resistance because of the large amount of infectious virus they produce, while viruses of equivalent virulence may produce different amounts of drug-resistant progeny because of alterations in the replication fidelity of the viral DNA polymerase.