Mark A. James

Antigenic and immunogenic studies on cell culture-derived Babesia canis

Babesia canis antigens derived from cell culture reacted specifically with immune serum from dogs convalescing from babesiosis. The antigens were heterogenous as compared to antigens elaborated in vivo. The major antigenic moiety from cell culture eluted in the first peak of Sephadex G-200 is indicative of a molecular weight around 900 000. In contrast, in vivo-derived antigen coeluted with albumin and hemoglobin suggesting a molecular weight of 67 000. The major antigenic mass is proteinacious and contains disulfide bonds as indicated by thermolability and sensitivity to 2-mercaptoethanol. Both particulate and soluble B. canis antigens were immunogenic, particularly when emulsified in Saponin as an adjuvant. Such antigens conferred a considerable degree of protection in Saponin as an adjuvant. Such antigens conferred a considerable degree of protection in susceptible dogs and it suggested that immunoprophylaxis to B. canis may be feasible.

Localization of culture-derived soluble Babesia bovis antigens in the infected erythrocyte☆

Immunoprecipitates derived from crossed immunoelectrophoresis of Babesia bovis culture supernatant fluid against a polyspecific anti-B. bovis serum were used to produce monospecific rabbit antibodies to individual B. bovis antigens. These antibodies were utilized in an immunofluorescence test to identify the location of the respective antigens within the infected erythrocyte. Two antigens were found on or near the erythrocyte membrane, while a third antigen was directly associated with the parasite itself.

Utilization of culture-derived soluble antigen in the latex agglutination test for bovine babesiosis and anaplasmosis☆

Abstract A simple lated agglutination test (LAT) for the diagnosis of Babesia bovis and Anaplasma marginale infection in cattle was developed using cell culture-derived soluble antigens to sensitize latex particles. The conditions to perform the test were established as follows: a 2% suspension of polystyrene latex particles (0.8 μm diameter) in 0.15 M glycine buffer pH 8.3 containing 0.2% disodium-EDTA was used to sensitize an equal vlume of antigen at a final antigen concentration between 0.625×–1.25× of the original antigen concentration of the supernatant culture medium. The latex particles were sensitized for 15 min at 56°C, The test, which uses heat-inactivated sera, was performed at room temperature by mixing one drop of each antigen and serum on a glass slide. T he LAT showed a high degree of specificity and sensitivity when compared with the babesiosis indirect fluorescent antibody (IFA) and anaplasmosis capillary tube-agglutination (CA) tests. The LAT possesses appropriate stability and simplicity suitable for field purposes.

An update of the isolation and characterization of culture-derived soluble antigens of Babesia bovis

In this paper recent progress concerning the identification of soluble antigens from cultures of Babesia bovis parasites is reviewed. Soluble antigens present in the supernatant of B. bovis cultures have been shown to be efficient immunogens for induction of protective immunity against bovine babesiosis. Immunochemical analysis of culture supernatants has demonstrated that at least 3 parasite antigens are released in vitro. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that at least 2 of these antigens have molecular weights within the range of 37 000-40 000 daltons. Crossed immunoelectrophoretic studies have further revealed an antigenic spectrum consisting of 1 major and 2 minor antigens with mobilities in the albumin and alpha 1 regions. Within the infected erythrocyte, 2 antigens have been localized on or near the erythrocytic membrane, while the third antigen appears to be directly associated with the parasite.

Hematologic values of normal Bolivian squirrel monkeys (Saimiri sciureus): a comparison between wild-caught and laboratory-bred male animals.

Complete and differential blood counts were conducted on 23 male squirrel monkeys (Saimiri sciureus) of Bolivian origin. The sample included 9 laboratory-bred and 14 wild-caught adult monkeys weighing between 600 and 1,500 g. The means of total white blood cell (WBC) counts, total hemoglobin and hematocrits of laboratory-bred animals were found to be significantly different from those of wild-caught monkeys (p less than 0.01). Other hematologic parameters showed no significant differences between the two experimental groups. 3 of 14 (21.0%) wild-caught animals each had 1 reactive lymphocyte and 7% of the same group had 10 nucleated erythrocytes per 100 WBC. No reactive lymphocytes or nucleated erythrocytes were observed in laboratory-bred animals. The importance of these baseline data and the basis for the differences observed between laboratory and wild-caught monkeys are discussed within the context of experimental studies involving primates in which hematologic parameters are valuable.

Plasmodium berghei: Effect of carrageenan on the course of infection in the A/J mouse

Abstract Seakem-9 calcium carrageenan, a reported anti-macrophage agent, was found to confer partial immunity in mice subsequently challenged with 5 × 10 5 Plasmodium berghei NK65A parasitized erythrocytes. Transient parasitemias and significantly extended survival times were evident in carrageenantreated animals. It was suggested that carrageenan may have enhanced nonspecific cellular immunological mechanisms or affected specific immune reactions through the cytotoxicity to suppressor macrophages.

Immunology of Babesia infections

Immunity to Babesia infection depends on general innate characteristics of the host in addition to its responsiveness to specific babesial antigens. The specific immune response includes both humoral and cellular components. Protective antibodies related to thymus-dependent lymphocyte activity probably damage extracellular merozoites and promote phagocytosis of free parasites and parasitized erythrocytes. There is now evidence that recovery from experimental Babesia infections in rodents is T-lymphocyte dependent with natural killer cells also participating in protective immune responses. Babesia bovis antigens derived from culture supernatant fluids or from infected erythrocyte lysates have recently been characterized as to their immunologic properties. These antigens are being effectively utilized as immunogens for vaccination against bovine babesiosis and also as reagents in newly-developed immunodiagnostic techniques.