Background: GDP-fucose and other sugar nucleotide biosynthetic pathways are conserved in the P. falciparum genome. Results: These pathways are active in the intraerythrocytic life cycle of the parasite. Conclusion:The parasite biosynthesizes GDP-fucose and other sugar nucleotides not related to the glycosylphosphatidylinositol structures Significance: Their presence strongly suggests that they are involved in the biosynthesis of glycans not yet characterized.

No abstract

No abstract

The disappearance of lytic, protective antibodies (Abs) from the serum of patients with Chagas disease is accepted as a reliable indicator of parasitological cure. The efficiency of a chemiluminescent enzyme-linked immunosorbent assay based on a purified, trypomastigote-derived glycosylphosphatidylinositol-anchored mucin antigen for the serologic detection of lytic Abs against Trypanosoma cruzi was evaluated in a nonendemic setting using a panel of 92 positive and 58 negative human sera. The technique proved to be highly sensitive {100%; 95% confidence interval (CI) = 96-100} and specific (98.3%; 95% CI = 90.7-99.7), with a kappa score of 0.99. Therefore, this assay can be used to detect active T. cruzi infection and to monitor trypanosomicidal treatment.

Glycosylation is an important posttranslational protein modification in all eukaryotes. Besides glycosylphosphatidylinositol (GPI) anchors and N-glycosylation, O-fucosylation has been recently reported in key sporozoite proteins of the malaria parasite. Previous analyses showed the presence of GDP-fucose (GDP-Fuc), the precursor for all fucosylation reactions, in the blood stages of Plasmodium falciparum. The GDP-Fuc de novo pathway, which requires the action of GDP-mannose 4,6-dehydratase (GMD) and GDP-L-fucose synthase (FS), is conserved in the parasite genome, but the importance of fucose metabolism for the parasite is unknown. To functionally characterize the pathway we generated a PfGMD mutant and analyzed its phenotype. Although the labelling by the fucose-binding Ulex europaeus agglutinin I (UEA-I) was completely abrogated, GDP-Fuc was still detected in the mutant. This unexpected result suggests the presence of an alternative mechanism for maintaining GDP-Fuc in the parasite. Furthermore, PfGMD null mutant exhibited normal growth and invasion rates, revealing that the GDP-Fuc de novo metabolic pathway is not essential for the development in culture of the malaria parasite during the asexual blood stages. Nonetheless, the function of this metabolic route and the GDP-Fuc pool that is generated during this stage may be important for gametocytogenesis and sporogonic development in the mosquito.

Thrombospondin type I repeat (TSR) domains are commonly O -fucosylated by protein O -fucosyltransferase 2 (PoFUT2), and this modification is required for optimal folding and secretion of TSR-containing proteins. The human malaria parasite Plasmodium falciparum expresses proteins containing TSR domains, such as the thrombospondin-related anonymous protein (TRAP) and circumsporozoite surface protein (CSP), which are O -fucosylated. TRAP and CSP are present on the surface of sporozoites and play essential roles in mosquito and human host invasion processes during the transmission stages. Here, we have generated PoFUT2 null-mutant P. falciparum and Plasmodium berghei (rodent) malaria parasites and, by phenotyping them throughout their complete life cycle, we show that PoFUT2 disruption does not affect the growth through the mosquito stages for both species. However, contrary to what has been described previously by others, P. berghei PoFUT2 null mutant sporozoites showed no deleterious motility phenotypes and successfully established blood stage infection in mice. This unexpected result indicates that the importance of O -fucosylation of TSR domains may differ between human and RODENT malaria parasites; complicating our understanding of glycosylation modifications in malaria biology.

Objective: To assess the agreement between two rapid detection tests (RDT) for antibodies against SARS-CoV-2 infection. Materials and methods: This was a cross-sectional study that used a random sample of nonhospitalized patients from the primary care management division of the Healthcare Area of Leon (58 RT-PCR-positive cases and 52 RT-PCR-negative cases). Information regarding symptoms was collected and all patients were simultaneously tested using two RDTs (Combined -cRDT and Differentiated -dRDT). The results of both tests were evaluated using the chi-square test and, for degree of agreement, the kappa coefficient. Results: About 52% of the participants were women (mean age: 48.2 ± 11.0 years). A total of 58.2% were positive for d-RDT and 41.2% were positive for c-RDT. In the subjects who were RT-PCR-positive, d-RDT was positive in 72.4% and c-RDT in 55.2%; in those who were RT-PCRnegative, the percentages were 42.3% and 26.9%, respectively. The kappa coefficient observed between the two RDTs was 0.644, and was higher in patients without a fever or anosmia (0.725) and lower in those with a fever or anosmia (0.524).

No abstract