Babesia parasites are major hemoprotozoa in a variety of animals, and the infections cause great economic losses in the livestock or companion animal industry worldwide. In this study, using anti-B. rodhaini immune serum, we examined the immunogenic proteins of B. rodhaini, which is a rodent species of Babesia and has been used as an experimental animal model for other babesioses. Immunological analyses with the immune serum showed wide localization in the parasite body as well as around the surface of infected red blood cells and the existence of at least 15 antigens. In addition, 10 groups of immunoreactive cDNA clones were obtained from a B. rodhaini-cDNA expression phage library by the immunoscreening technique with the immune serum. It is hoped that these results will supply useful materials for the development of babesial subunit vaccines.
Monthly collections were made of all male and female ticks from 10 female cows (Bos taurus crosses) between 18 months and 4 years of age, once a month over a period of 12 months at monthly intervals at Qwa‐Qwa in the Eastern Free State province, South Africa, from May 1998 to April 1999. The most common species were Boophilus decoloratus Koch and Rhipicephalus evertsi evertsi Neumann. Rhipicephalus follis Donitz, R. gertrudae Feldman-Muhsam and R. punctatus Warburton were also present in fewer numbers. Cattle were ranked according to their degree of resistance to the total tick infestations. Tick numbers varied throughout the year on all individuals but some animals consistently tended to have either higher or lower numbers than the mean of the group. Tick burdens on cattle classified as having a relatively low resistance to tick infestations increased eleven-fold, compared to a four-fold increase on cattle with high resistance from August 1998 to April 1999. Thirty-two percent of the cattle in the total study group (n=10) carried 50% of the total tick burden. Farmers in the region can visually assess B. decoloratus and R. evertsi evertsi burdens, the most abundant tick species, and sell or cull the most susceptible cattle. This should eventually result in the direct improvement of the overall tick resistance of their cattle and will help in management and control of tick populations infesting their animals.
The in vitro culture of bovine Theileria orientalis sergenti and the suitability of the Bovine RBC-SCID (Bo-RBC-SCID) mouse model in-aid of parasite cultivation are herein presented. Viable parasites were successfully maintained in culture at low oxygen atmosphere (5% O2,5% CO2 and 90% N2) for one month requiring three subcultures. Supplementation of RPMI 1640 medium with 40% adult bovine serum (ABS) gave the most satisfying 4-14.5% increase in parasitemia. From all indications, parasites in ABS-supplemented cultures, and those obtained from Bo-RBC-SCID mice appeared viable and normal. The parasite-specific p33 gene fragment was amplified in Bo-RBC-SCID mouse blood samples obtained at 30 days post-transfusion. To our knowledge, present data represent the first reported long-term cultivation of T. o. sergenti in vitro in tandem with the in vivo Bo-RBC SCID mouse system.
The physical and chemical treatments for elimination of pathogens from human plasma fraction (HPF) are very important for transfusion therapy. In this study, we evaluated the safety by the sterile filtration, virus removal filtration, heat inactivation and alcohol treatment of human albumin fraction containing Babesia microti. Following treatments, mice were challenged infection to establish a model for detection of B. microti in HPF. We chose the same methods to process the globulin and albumin fractions, as with the treatments of the samples. As a result, we did not detect parasites in mice inoculated with all treated samples when Giemsa-stained thin blood smears from the challenged mice were examined for 51 days.
However, by immunofluorescent antibody assay, we found some parasites in the sample which had been filtrated by a sterility filter (0.2µm). This suggests that B. microti might be able to pass through the routinely employed sterile filter, and babesiosis might occur when the manufacturing process includes the sterile filtration only. It is suggested that blood plasma products which have been introduced with the multiple processes of virus removal and/or inactivation such as alcohol fractionation, pasturization, chemical treatment, virus removal filtration to their manufacturing process, might be safe against protozoa infections.