Epidemiological surveys of camel trypanosomosis in Al-jouf, Saudi Arabia based on PCR and ELISA

Trypanosomosis due to Trypanosoma evansi (surra) is a major enzootic disease of the dromedary camel. The present study was conducted to determine the prevalence of camel trypanosomosis in the northern part of Saudi Arabia with different methods of diagnosis (ELISA, PCR) and to compare the results to whose obtained previously with Card Agglutination Test for Trypanosomiasis (CATT/T.evansi). A total of 195 blood samples and 118 serum samples were used for molecular and serological investigation respectively. After analyses, 25% (49/195) and 3% (4/118) samples were positive using PCR and ELISA respectively. The variability of trypanosomosis was highly significant to the factor moving, location, breed and clinical signs with PCR. The discrepancy between PCR, CATT test and ELISA is likely due to antibodies degradation on spotted papers maintained several weeks at ambient temperature. This is the first molecular diagnosis report which gives a picture of camel trypanosomosis in Al-jouf, Saudi Arabia

Pericentric heterochromatin reprogramming by new histone variants during mouse spermiogenesis

During male germ cell postmeiotic maturation, dramatic chromatin reorganization occurs, which is driven by completely unknown mechanisms. For the first time, we describe a specific reprogramming of mouse pericentric heterochromatin. Initiated when histones undergo global acetylation in early elongating spermatids, this process leads to the establishment of new DNA packaging structures organizing the pericentric regions in condensing spermatids. Five new histone variants were discovered, which are expressed in late spermiogenic cells. Two of them, which we named H2AL1 and H2AL2, specifically mark the pericentric regions in condensing spermatids and participate in the formation of new nucleoprotein structures. Moreover, our investigations also suggest that TH2B, an already identified testis-specific H2B variant of unknown function, could provide a platform for the structural transitions accompanying the incorporation of these new histone variants

Differences in pathogenicity and virulence of Trypanosoma brucei gambiense field isolates in experimentally infected Balb/C mice

Trypanosoma brucei gambiense (T. b. gambiense) is the major causative agent of human African trypanosomiasis (HAT). A great variety of clinical outcomes have been observed in West African foci, probably due to complex host-parasite interactions. In order to separate the roles of parasite genetic diversity and host variability, we have chosen to precisely characterize the pathogenicity and virulence of T. b. gambiense field isolates in a mouse model. Thirteen T. b. gambiense strains were studied in experimental infections, with 20 Balb/C infected mice per isolate. Mice were monitored for 30 days, in which mortality, parasitemia, anemia, and weight were recorded. Mortality rate, prepatent period, and maximum parasitemia were estimated, and a survival analysis was performed to compare strain pathogenicity. Mixed models were used to assess parasitemia dynamics, weight, and changes in Packed Cell Volume (PCV). Finally, a multivariate analysis was performed to infer relationships between all variables. A large phenotypic diversity was observed. Pathogenicity was highly variable, ranging from strains that kill their host within 9 days to a non-pathogenic strain (no deaths during the experiment). Virulence was also variable, with maximum parasitemia values ranging from 42 million to 1 billion trypanosomes/ml. Reduced PCV and weight occurred in the first two weeks of the infection, with the exception of two strains. Finally, the global analysis highlighted three groups of strains: a first group with highly pathogenic strains showing an early mortality associated with a short prepatent period; a second group of highly virulent strains with intermediate pathogenicity; and a third group of isolates characterized by low pathogenicity and virulence patterns. Such biological differences could be related to the observed clinical diversity in HAT. A better understanding of the biological pathways underlying the observed phenotypic diversity could thus help to clarify the complex nature of the host-parasite interactions that determine the resistance/susceptibility status to T. brucei gambiense

A Spatio-temporal Model of African Animal Trypanosomosis Risk

[b]Background[/b]African animal trypanosomosis (AAT) is a major constraint to sustainable development of cattle farming in sub-Saharan Africa. The habitat of the tsetse fly vector is increasingly fragmented owing to demographic pressure and shifts in climate, which leads to heterogeneous risk of cyclical transmission both in space and time. In Burkina Faso and Ghana, the most important vectors are riverine species, namely Glossina palpalis gambiensis and G. tachinoides, which are more resilient to human-induced changes than the savannah and forest species. Although many authors studied the distribution of AAT risk both in space and time, spatio-temporal models allowing predictions of it are lacking.[b]Methodology/Principal Findings[/b]We used datasets generated by various projects, including two baseline surveys conducted in Burkina Faso and Ghana within PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign) national initiatives. We computed the entomological inoculation rate (EIR) or tsetse challenge using a range of environmental data. The tsetse apparent density and their infection rate were separately estimated and subsequently combined to derive the EIR using a "one layer-one model" approach. The estimated EIR was then projected into suitable habitat. This risk index was finally validated against data on bovine trypanosomosis. It allowed a good prediction of the parasitological status (r(2) = 67%), showed a positive correlation but less predictive power with serological status (r(2) = 22%) aggregated at the village level but was not related to the illness status (r(2) = 2%).[b]Conclusions/Significance[/b]The presented spatio-temporal model provides a fine-scale picture of the dynamics of AAT risk in sub-humid areas of West Africa. The estimated EIR was high in the proximity of rivers during the dry season and more widespread during the rainy season. The present analysis is a first step in a broader framework for an efficient risk management of climate-sensitive vector-borne diseases

Whole blood transcriptome profiles of trypanotolerant and trypanosusceptible cattle highlight a differential modulation of metabolism and immune response during infection by Trypanosoma congolense

Animal African trypanosomosis, caused by blood protozoan parasites transmitted mainly by tsetse flies, represents a major constraint for millions of cattle in sub-Saharan Africa. Exposed cattle include trypanosusceptible indicine breeds, severely affected by the disease, and West African taurine breeds called trypanotolerant owing to their ability to control parasite development, survive and grow in enzootic areas. Until now the genetic basis of trypanotolerance remains unclear. Here, to improve knowledge of the biological processes involved in trypanotolerance versus trypanosusceptibility, we identified bovine genes differentially expressed in five West African cattle breeds during an experimental infection by Trypanosoma congolense and their biological functions. To this end, whole blood genome-wide transcriptome of three trypanotolerant taurine breeds (N’Dama, Lagune and Baoulé), one susceptible zebu (Zebu Fulani) and one African taurine x zebu admixed breed (Borgou) were profiled by RNA sequencing at four time points, one before and three during infection. As expected, infection had a major impact on cattle blood transcriptome regardless of the breed. The functional analysis of differentially expressed genes over time in each breed confirmed an early activation of the innate immune response, followed by an activation of the humoral response and an inhibition of T cell functions at the chronic stage of infection. More importantly, we highlighted overlooked features, such as a strong disturbance in host metabolism and cellular energy production that differentiates trypanotolerant and trypanosusceptible breeds. N’Dama breed showed the earliest regulation of immune response, associated with a strong activation of cellular energy production, also observed in Lagune, and to a lesser extent in Baoulé. Susceptible Zebu Fulani breed differed from other breeds by the strongest modification in lipid metabolism regulation. Overall, this study provides a better understanding of the biological mechanisms at work during infection, especially concerning the interplay between immunity and metabolism that seems differentially regulated depending on the cattle breeds

Cloning, expression, molecular characterization and preliminary studies on immunomodulating properties of recombinant Trypanosoma congolense calreticulin

Trypanosomes are bloodstream protozoan parasites, which are pathogens of veterinary and medical importance. Several mammalian species, including humans, can be infected by different species of the genus Trypanosoma (T. congolense, T. evansi, T. brucei, T. vivax) exhibiting more or less virulent and pathogenic phenotypes. A previous screening of the excreted-secreted proteins of T. congolense demonstrated an overexpression of several proteins correlated with the virulence and pathogenicity of the strain. Of these proteins, calreticulin (CRT) has shown differential expression between two T. congolense strains with opposite infectious behavior and has been selected as a target molecule based on its immune potential functions in parasitic diseases. In this study, we set out to determine the role of T. congolense calreticulin as an immune target. Immunization of mice with recombinant T. congolense calreticulin induced antibody production, which was associated with delayed parasitemia and increased survival of the challenged animal. These results strongly suggest that some excreted-secreted proteins of T. congolense are a worthwhile target candidate to interfere with the infectious process