Target fishing reveals PfPYK-1 and PfRab6 as potential targets of an antiplasmodial 4-anilino-2-trichloromethylquinazoline hit compound.

We present investigations about the mechanism of action of a previously reported 4-anilino-2-trichloromethylquinazoline antiplasmodial hit-compound (Hit A), which did not share a common mechanism of action with established commercial antimalarials and presented a stage-specific effect on the erythrocytic cycle of P. falciparum at 8 < t < 16 h. The target of Hit A was searched by immobilising the molecule on a solid support via a linker and performing affinity chromatography on a plasmodial lysate. Several anchoring positions of the linker (6,7 and 3') and PEG-type linkers were assessed, to obtain a linked-hit molecule displaying in vitro antiplasmodial activity similar to that of unmodified Hit A. This allowed us to identify the PfPYK-1 kinase and the PfRab6 GTP-ase as potential targets of Hit A.

Detection of Toxoplasma gondii oocysts in environmental soil samples using molecular methods.

Infections caused by Toxoplasma gondii are prevalent in humans and animals throughout the world. So far, there is no sufficient information concerning T. gondii oocysts prevalence in the environment, especially in soil. Therefore, the aim of this study was to estimate occurrence of T. gondii oocysts in soil and determine the genotype of detected parasites. A total of 101 soil samples were taken from different sites (sand-pits, "farming ground", areas around rubbish dumps) located in the Tri-City (Poland). Oocysts were recovered using the flotation method. Then, PCR reactions targeting the B1 gene were performed for specific T. gondii detection. The positive samples were further confirmed by PCR amplification of a repetitive element (REP) sequence [GenBank accession number AF146527]. Toxoplasma DNA was found in 18 samples. Among them, seven samples were successfully genotyped at the SAG2 locus. They were classified as SAG2 type I (5 samples) and SAG2 type II (2 samples). This is one of the first investigations describing T. gondii oocyst detection in environmental soil samples with rapid molecular detection methods and genotyping. The results of our findings showed that soil contaminated with T. gondii oocysts may play a role in the epidemiology of human toxoplasmosis in Poland.

Serological survey of caprine toxoplasmosis in Ethiopia: prevalence and risk factors.

The study was conducted to determine the prevalence and risk factors of toxoplasmosis in goats in Southern and central Ethiopia between October 2005 and May 2006. A total of 641 goats sera were tested using Modified Direct Agglutination Test (MAT), of which 480 (74.8% CI: 71.3, 78.2) were found to be positive. The highest prevalence was recorded in South Omo zone (82%) while the lowest was observed in East Shewa zone (62.2%). The study revealed that goats raised in southern Ethiopia are at a greater risk of acquiring T. gondii infection (OR = 2.55, CI: 1.726, 3.776; p = 0.000) than those which are raised in central Ethiopia. The prevalence of anti T. gondii antibody was significantly higher in older goats than in kids (OR = 2.33, CI: 1.490, 3.655; p < 0.0002) and in females than in males (p < 0.0007; OR = 0.68, CI: 0.542, 0.849). No significant difference was observed among goats kept under various husbandry practices. The high prevalence of toxoplasmosis in Ethiopian goats suggests a high risk of human infections. Further epidemiological investigation, isolation and genotyping of T. gondii are planned.

Genetic diversity, clonality and sexuality in Toxoplasma gondii.

The majority of Toxoplasma gondii strains from a variety of human and animal sources have been grouped into three highly clonal but closely related lineages. The low occurrence of nucleotide differences among the three predominant lineages and their unusual dimorphic allelic composition suggest that they have arisen from a recent common ancestry. Less than 1% of the previously studied strains contain unique genotypes and high divergence of DNA sequence, and therefore are considered 'exotic' or 'atypical' strains. The seemingly low genetic diversity in T. gondii may have been underestimated because most parasite strains in previous studies were collected from human patients and domestic animals in North America and Europe. To investigate the genetic diversity of T. gondii, we analysed parasite strains isolated from remote geographical regions by multilocus microsatellite sequencing and phylogenetic analysis. The genetic diversity indices, the molecular analysis of microsatellite genotypes and the constructed phylogram considered together suggest that the global T. gondii population is highly diversified and not characteristic of a clonal organism. The most parsimonious hypothesis is that T. gondii presents a complex population structure with a mix of clonal and sexual propagation as a function of the environmental conditions. The comparison between domestic strains data on one hand and wild strains data on the other hand is in favour of more frequent sexual recombinations in wild environment even though Toxoplasma subpopulation in human and domestic animals is largely clonal.