Analysis of mixed parasite populations ofTheileria sergentiusing cDNA probes encoding a major piroplasm surface protein

Abstract

The gene for the 32 kDa surface protein (p32) of Theileria sergenti was cloned into lambda gt11 and its nucleotide sequence was determined. The gene encodes a protein of 283 amino acids as deduced from its nucleotide sequence with a 22 residue N-terminal signal peptide. Using this cDNA as a probe we have isolated another two clones from a cDNA library with a CDM8 vector system derived from the same parasite stock. Comparison with three cDNA clones revealed differential polyadenylation and differences in sequences of non-coding regions. Within the coding regions, there were nucleotide transitions which affected the Pst I-restriction site, and one of the transitions was also accompanied by an amino acid substitution (Ala to Gly). Southern blot analysis showed hybridization pattern changes among the parasites isolated from individual calves at different times after infection. From these results, we conclude that at least 3 genetically different parasite populations may coexist, and the transition to predominant parasite populations might occur during persistent infections in a host, possibly to evade the host immune responses.

Survey of Theileria Parasite Infection in Cattle in Taiwan.

“…Previously, we developed the polymerase chain reaction (PCR) technique to specifically amplify a gene of a major piroplasm surface protein, p32 of T. sergenti, and it is significantly more sensitive than the serological test [7]. Among T. sergenti isolated from different areas in Japan, genetic diversities were detected by Southern blotting using probes of genomic DNA clones [9] and cDNA clones encoding a p32 [8]. Most parasite stocks and field isolates consisted of mixed populations [12] of genetically and antigenically different parasites.…”

“…After amplification, 5-10 µl of each sample were subjected to agarose gel electrophoresis. Southern blotting of PCR product was carried out as described previously [8] using 32 P-labelled cDNA clone L9-1 probe derived from C type parasite of T. sergenti [8].…”

Molecular Characterization of Theileria orientalis Piroplasm Protein Encoded by an Open Reading Frame (To ORF2) in a Genomic Fragment

“…However, little is known on stage specific expression of T. orientalis proteins. Only two piroplasm proteins, the major piroplasm surface protein (MPSP) [12,15] and P23 [29] have been reported although the erythrocytic stage is responsible for the pathology associated with theileriosis caused by T. orientalis. For other stages such as sporozoite or schizont, no specific genes have been identified so far.…”

Expression of a Major Piroplasm Surface Protein of Theileria sergenti in Sporozoite Stage.

“…The cDNA library was prepared from infected tick salivary glands and immunoscreened with a serum from infected cattle which mainly contained antibodies against MPSP, essentially as described by Matsuba et al [9]. The nucleotide sequences of two positive cDNA clones were determined.…”