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Vaccines based on recombinant Bm86 gut antigen from Boophilus microplus are a useful component of integrated control strategies against B. microplus infestations of cattle. The capacity of such vaccines to control heterologous infestations by two African tick species was investigated. The mean weight of engorged female ticks and mean egg mass per tick were significantly reduced in B. decoloratus infestations, but there was no effect of the vaccine against adult Rhipicephalus appendiculatus. We cloned, sequenced and expressed two Bm86 homologues (Bd86) from B. decoloratus. Amino acid sequence identity between Bd86 homologues (Bd86-1 and Bd86-2) and Bm86 was 86% and 85%, respectively, compared to 93% identity between the variants. Native Bd86 protein in B. decoloratus tick mid-gut sections and recombinant Bd86-1 reacted strongly with sera from TickGARD vaccinated cattle. TickGARD can therefore protect against a heterologous tick species with multiple antigen sequences. Epitope mapping using sera from TickGARD-vaccinated cattle identified two linear peptides conserved between the Bd86 homologues and Bm86. These epitopes represent candidate synthetic peptide vaccines for control of Boophilus spp. and the pathogens transmitted by these tick vectors.

As a first step in developing compartment-specific markers for protein trafficking within Theileria parva, we have isolated cDNAs encoding homologues of the small GTP binding proteins Rab1 and Rab4. The T. parva homologue of Rab1 (TpRab1), a protein which regulates vesicular transport between the endoplasmic reticulum and cis golgi in other organisms, was unusual in that it contained a unique 17 amino acid C-terminal extension. The C-terminal motif sequence KCT (XCX) contrasted with the CXC or XCC motifs which act as as signals for isoprenylation by geranylgeranyl in most Rab proteins, including all known Rab1 homologues, in containing only a single cysteine. [C14]mevalonic acid lactone and [H3]geranylgeranyl pyrophosphate were specifically incorporated into recombinant TpRab1 in vitro, demonstrating that the novel motif was functional for isoprenylation. Recombinant TpRab1 bound radiolabeled GTP, and this binding was inhibited by excess unlabeled GTP and GDP and also partially by ATP. The TpRab1 gene contained four short (34–67 bp) introns with a distinct pattern of occurrence within the protein sequence as compared to the introns of other lower eukaryote Rab1 genes. Immunofluorescence microscopy using antiserum specific for the novel C-terminal peptide in combination with labelling of cells using the nucleic acid-staining dye DAPI, indicated that TpRab1 was located in the vicinity of the schizont nucleus within the infected lymphocyte.

DNAs of Theileria parva parva, T. p. lawrencei, T. p. bovis and Theileria mutans stocks, from Kenya, Uganda, Zanzibar and Zimbabwe were digested with either Sfi I or Not I and analysed using contour-clamped homogeneous electric field (CHEF) and field-inversion gel electrophoresis (FIGE). The Sfi I-digested T. parva genomic DNA resolved into approximately 30 fragments while the Not I digestion produced between 4–7 bands. The summation of the sizes of Sfi I fragments gave an estimate of 9–10×10 6 base pairs for the size of the T. parva genome. Heterogeneity within T. p. parva Muguga, Pemba/Mnarani and Mariakani stocks was detected. All the T. parva stocks analysed showed Sfi I and Not I restriction fragment length polymorphisms (RFLP). Hybridisation of 5 Sfi I-digested T. parva DNAs with a Plasmodium berghei telomeric repeat probe suggested that most of the polymorphisms and heterogeneity occurred in the telomeric or sub-telomeric regions of the genome. The recognition by the Plasmodium telomeric probe of 7–8 strongly hybridising Sfi I bands indicates that the T. parva genome may possess at least 4 chromosomes. The T. mutans genome was cut frequently with the above enzymes resulting in large numbers of fragments predominantly below 50 kb, thus suggesting either a much higher G+C content than T. parva or the presence of highly reiterated G+C-rich regions.

Palmer G. H., Barbet A. F., Musoke A. J., Katende J. M., Rurangirwa F., Shkap V., Pipano E., Davis W. C. and Mcguire T. C. 1988. Recognition of conserved surface protein epitopes on Anaplasma centrale and Anaplasma marginale isolates from Israel, Kenya and the United States. International Journal for Parasitology18: 33–38. Field isolates of A. marginale from Israel, Kenya and the United States and Anaplasma centrale were shown to be antigenically distinct using a panel of 1:1 isolaterestricted monoclonal antibodies. One monoclonal antibody reacted with all A. marginale isolates but not A. centrale and may be species-specific. A second panel of seven antibodies detected epitopes common to all isolates and both species. These common epitopes were present on two major Anaplasma surface proteins of Mr 36,000 and Mr 105,000. Monoclonal antibodies capable of neutralizing heterologous A. marginale isolate infectivity recognized 100% of the organisms in each isolate including A. centrale. In addition, immune sera from cattle recovered from infection with each of the isolates contained high titer antibodies to the isolated surface proteins bearing the common epitopes. These results demonstrate that antigenically distinct Anaplasma isolates and species contain common surface epitopes that may be important in developing effective immunoprophylaxis.