Ana Maria Sastre Sacco

Association between microsatellite markers of sheep chromosome 5 and faecal egg counts

Abstract This study analyses the associations between alleles at seven microsatellite markers located at the sheep chromosome 5—where the interleukin IL-3, IL-4 and IL-5 genes were mapped—and faecal egg counts (FEC) in two different flocks. The associations were analysed by estimating the average excess of alleles at each microsatellite marker on FEC. Three of the studied markers (CSRD2138, OarAE129 and TGLA176) showed significant associations with FEC in the Corriedale flock. Seven alleles at these microsatellite loci were associated with FEC and their effects ranged from −28 to +20%, relative to the FEC population mean. On the other hand, four alleles at CSRD2138 and TGLA176 microsatellite markers had significant associations with FEC in the Polwarth mob, with effects varying from −22 to −5%, relative to the FEC population mean. All microsatellites investigated presented high diversity in both flocks. Some alleles were breed specific. The CSRD2138 ∗ A allele was the only marker associated with consistent reductions in FEC for both breeds. These results indicate that markers or genes nearby the interleukin genes, such as the CSRD2138, might enhance host resistance to internal parasites in sheep by probably increasing effector cells and antibody responses.

Molecular and antigenic characterisation of ribosomal phosphoprotein P0 from Babesia bovis

Babesia bovis is a tick-borne pathogen that remains an important constraint for the development of cattle industries in tropical and subtropical regions of the world. Effective control can be achieved by vaccination with live attenuated phenotypes of the parasite. However, these phenotypes have a number of drawbacks, which justifies the search for new, more efficient immunogens based mainly on recombinant protein technology. In the present paper, ribosomal phosphoprotein P0 from a Brazilian isolate of B. bovis was produced and evaluated with regard to conservation and antigenicity. The protein sequence displayed high conservation between different Brazilian isolates of B. bovis and several Apicomplexa parasites such as Theileria, Neospora and Toxoplasma. IgG from cattle experimentally and naturally infected with B. bovisas well as IgG1 and IgG2 from naturally infected cattle reacted with the recombinant protein. IgG from cattle experimentally infected with Babesia bigemina cross-reacted with B. bovis recombinant P0. These characteristics suggest that P0 is a potential antigen for recombinant vaccine preparations against bovine babesiosis.

Cepas atenuadas de Babesia bovis e Babesia bigemina e de Anaplasma centrale como imunógenos no controle da tristeza parasitária bovina

Attenuated strains of Babesia bovis and B. bigemina and a strain of Anaplasma centrale were evaluated as immunogens against tick-borne disease. The immunization process was shown to be inocuous, immunogenic and efficient to protect cattle, at least against the babesias. Vaccinated animals proved to be protected when naturally challenged with heterologous and virulent strains, in contrast to control animals that showed clinical symptoms of the disease and had to be treated. The Anaplasma marginale challenge was not efficient since treatment was not necessary in the control animals, therefore it was not possible to conclude that immunization with A. centrale protected animals against anaplasmosis.