Analysis of Theileria parva immunodominant schizont surface antigen by two-dimensional polyacrylamide gel electrophoresis and immunoblotting

Gene gun DNA immunization of cattle induces humoral and CD4 T-cell-mediated immune responses against the Theileria parva polymorphic immunodominant molecule

Theileria parva kills over one million cattle annually in sub-Saharan Africa. Parasite genetic complexity, cellular response immunodominance, and bovine MHC diversity have precluded traditional vaccine development. One potential solution is gene gun (GG) immunization, which enables simultaneous administration of one or more DNA-encoded antigens. Although promising in murine, porcine, and human vaccination trials, bovine GG immunization studies are limited. We utilized the model T. parva antigen, polymorphic immunodominant molecule (PIM) to test bovine GG immunization. GG immunization using a mammalian codon optimized PIM sequence elicited significant anti-PIM antibody and cell-mediated responses in 7/8 steers, but there was no difference between immunized and control animals following T. parva challenge. The results suggest immunization with PIM, as delivered here, is insufficient to protect cattle from T. parva. Nonetheless, the robust immune responses elicited against this model antigen suggest GG immunization is a promising vaccine platform for T. parva and other bovine pathogens.

Tick-borne diseases in cattle: applications of proteomics to develop new generation vaccines

Tick-borne diseases (TBDs) affect 80% of the world's cattle population, hampering livestock production throughout the world. Livestock industry is important to rural populations not only as food supply, but also as a source of income. Tick control is usually achieved by using acaricides which are expensive, deleterious to the environment and can induce chemical resistance of vectors; the development of more effective and sustainable control methods is therefore required. Theileriosis, babesiosis, anaplasmosis and heartwater are the most important TBDs in cattle. Immunization strategies are currently available but with variable efficacy. To develop a new generation of vaccines which are more efficient, cheaper and safer, it is first necessary to better understand the mechanisms by which these parasites are transmitted, multiply and cause disease; this becomes especially difficult due to their complex life cycles, in vitro culture conditions and the lack of genetic tools to manipulate them. Proteomics and other complementary post-genomic tools such as transcriptomics and metabolomics in a systems biology context are becoming key tools to increase knowledge on the biology of infectious diseases. Herein, we present an overview of the so called "Omics" studies currently available on these tick-borne pathogens, giving emphasis to proteomics and how it may help to discover new vaccine candidates to control TBDs.

Expression of a major piroplasm surface protein of Theileria sergenti in sporozoite stage

A 32 kilodalton major piroplasm surface protein (MPSP) is expressed abundantly on the surface of intraerythrocytic piroplasms of Theileria sergenti and is considered to be a candidate antigen for vaccine development against piroplasmosis. In this study, transcripts of MPSP gene were detected in an expression cDNA library prepared from T. sergenti-infected tick salivary glands. Expression of MPSP in the sporozoite stage was also confirmed by immunoblot analysis. Its expression at the sporozoite and intraerythrocytic stages gives scope for possible induction of protective immunity being targeted at both stages by immunization with recombinant MPSP.

Humoral immune responses to Theileria parva in cattle as measured by two-dimensional western blotting

Humoral immune responses to schizont antigens from six stocks of Theileria parva were compared by two-dimensional Western blotting using sera from cattle that had been infected with a T. parva stock or a clone. Isoelectric points of a polymorphic immunodominant molecule (PIM) of schizonts that induces strong antibody responses in cattle ranged from acidic to basic. Molecular masses (Mr) of the PIM of the respective T. parva stocks were as follows: T. parva Muguga, 86 kDa; Mariakani, 83 kDa; Marikebuni, 83 kDa; Uganda, 83 kDa; T. parva Boleni, 83 kDa; and T. parva 7014, 100 kDa. Among nine cattle infected with T. parva Muguga, four produced antibodies to a basic antigen having an Mr of 32 kDa. The PIM of T. parva Muguga, T. parva Boleni, and T. parva 7014 reacted strongly with serum obtained from an animal that had been infected with T. parva Muguga. Two-dimensional Western blotting using antischizont monoclonal antibodies enabled us to differentiate between stocks of T. parva.

Characterisation of a glutamine- and proline-rich protein (QP protein) from Theileria parva

We have isolated a clone from a Theileria parva infected lymphocyte cDNA library which has the potential to encode a protein of 480 amino acids. This protein is particularly rich in glutamine and proline and has some short repeated amino acid motifs based on the sequences QPXP and QPXQ. We have called it the 'QP protein'. Southern blotting suggests that the QP protein gene is present as a single copy in the T. parva Muguga genome. Northern blotting revealed that the gene is transcribed in both schizonts and piroplasms. We have expressed part of the QP protein as a fusion with glutathione S-transferase in Escherichia coli and used this product to raise an anti-QP protein serum. Western blots of T. parva lysates using this serum showed a major polypeptide of approximately 100 kDa and two further polypeptides of approximately 67 and 72 kDa. Indirect immunofluorescence assays using the anti-QP protein serum on infected cells showed that the protein is associated with the schizont. The pattern of staining in the indirect immunofluorescence assays and the structure of the protein suggest that it is a component of the schizont membrane.