Trypanosoma vivax Adhesion to Red Blood Cells in Experimentally Infected Sheep.

Trypanosomosis, a globally occurring parasitic disease, poses as a major obstacle to livestock production in tropical and subtropical regions resulting in tangible economic losses. In Latin America including Venezuela, trypanosomosis of ruminants is mainly caused by Trypanosoma vivax. Biologically active substances produced from trypanosomes, as well as host-trypanosome cellular interactions, contribute to the pathogenesis of anemia in an infection. The aim of this study was to examine with a scanning electron microscope the cellular interactions and alterations in ovine red blood cells (RBC) experimentally infected with T. vivax. Ovine infection resulted in changes of RBC shape as well as the formation of surface holes or vesicles. A frequent observation was the adhesion to the ovine RBC by the trypanosome's free flagellum, cell body, or attached flagellum in a process mediated by the filopodia emission from the trypanosome surface. The observed RBC alterations are caused by mechanical and biochemical damage from host-parasite interactions occurring in the bloodstream. The altered erythrocytes are prone to mononuclear phagocytic removal contributing to the hematocrit decrease during infection.

Transcriptome analysis of the bloodstream stage from the parasite Trypanosoma vivax.

BACKGROUND: Trypanosoma vivax is the earliest branching African trypanosome. This crucial phylogenetic position makes T. vivax a fascinating model to tackle fundamental questions concerning the origin and evolution of several features that characterize African trypanosomes, such as the Variant Surface Glycoproteins (VSGs) upon which antibody clearing and antigenic variation are based. Other features like gene content and trans-splicing patterns are worth analyzing in this species for comparative purposes. RESULTS: We present a RNA-seq analysis of the bloodstream stage of T. vivax from data obtained using two complementary sequencing technologies (454 Titanium and Illumina). Assembly of 454 reads yielded 13385 contigs corresponding to proteins coding genes (7800 of which were identified). These sequences, their annotation and other features are available through an online database presented herein. Among these sequences, about 1000 were found to be species specific and 50 exclusive of the T. vivax strain analyzed here. Expression patterns and levels were determined for VSGs and the remaining genes. Interestingly, VSG expression level, although being high, is considerably lower than in Trypanosoma brucei. Indeed, the comparison of surface protein composition between both African trypanosomes (as inferred from RNA-seq data), shows that they are substantially different, being VSG absolutely predominant in T. brucei, while in T. vivax it represents only about 55%. This raises the question concerning the protective role of VSGs in T. vivax, hence their ancestral role in immune evasion.It was also found that around 600 genes have their unique (or main) trans-splice site very close (sometimes immediately before) the start codon. Gene Ontology analysis shows that this group is enriched in proteins related to the translation machinery (e.g. ribosomal proteins, elongation factors). CONCLUSIONS: This is the first RNA-seq data study in trypanosomes outside the model species T. brucei, hence it provides the possibility to conduct comparisons that allow drawing evolutionary and functional inferences. This analysis also provides several insights on the expression patterns and levels of protein coding sequences (such as VSG gene expression), trans-splicing, codon patterns and regulatory mechanisms. An online T. vivax RNA-seq database described herein could be a useful tool for parasitologists working with trypanosomes.

Serological evidence of Anaplasma spp. in small ruminants from Venezuela using recombinant MSP5 in immunoenzymatic assay / Evidencia serológica de Anaplasma spp. en pequeños rumiantes de Venezuela utilizando MSP5 recombinante en ensayos inmunoenzimáticos

Anaplasma marginale causes a disease in cattle characterized by fever, anemia and decrease in milk and meat production. Small ruminants do not show signs of disease when infected, but it has been suggested they could act as reservoirs. Goat and sheep breeding is socially and economically important in arid and semi-arid areas in Venezuela, and these species often share space and food with cattle. The aim of this work was to detect antibodies against Anaplasma spp. in Venezuelan goat and sheep flocks. To accomplish this goal, an indirect ELISA using recombinant MSP5 as antigen of A. marginale was performed. Sera obtained from experimental infection in goat and a hyperimmune sheep serum were used as positive controls. Blood sera were obtained from 45 sheep and 48 goats located in Guárico State, an endemic area to bovine anaplasmosis. After standardization of assay for each species, 80.46% of the sheep and 59.25% of the goat sera showed to have antibodies against MSP5. No signs of clinical disease were detected in sampled animals. These results suggest that small ruminants could harbour A. marginale and consequently may be reservoirs for neighbouring cattle if appropriate vectors are present. The development of clinical diseases caused by A. marginale under stress situations and the existence of other Anaplasma species (e.g. A. ovis) in small ruminants should also be investigated.

Anaplasma marginale ocasiona una enfermedad en los bovinos caracterizada por fiebre, anemia y disminución de la producción de leche y carne. Los pequeños rumiantes generalmente no muestran signos clínicos, por lo que pudieran actuar como reservorio. En Venezuela, los ovinos y caprinos tienen gran importancia económica y socialmente en zonas áridas y semi- áridas e incluso, en muchas ocasiones comparten su espacio y alimento con los bovinos. El objetivo de este trabajo fue detectar anticuerpos contra Anaplasma spp. en rebaños de ovinos y caprinos. Para ello, se estandarizó un ELISA indirecto con la MSP5 recombinante de A. marginale, empleando sueros provenientes de infecciones experimentales en caprinos y un suero hiperinmune ovino como controles positivos. Posteriormente, fueron obtenidos sueros sanguíneos de 45 ovinos y 48 caprinos localizados en una zona endémica a anaplasmosis bovina del estado Guárico. De estos, 80,46% de los ovinos y 59,25% de los caprinos presentaron anticuerpos que reconocieron la MSP5, sin embargo, ninguno de estos animales positivos presentaron signos clínicos de la enfermedad. Estos resultados sugieren que los pequeños rumiantes son portadores de A. marginale y por ende, pueden estar actuando como reservorio de la enfermedad para los bovinos en el caso que se encuentren los vectores apropiados. Por lo tanto, se debe profundizar en los estudios sobre el desarrollo de sintomatología clínica en condiciones de estrés y la existencia de otras especies de Anaplasma (como A. ovis) en los ovinos y caprinos de Venezuela.