The Trypanosoma brucei MISP family of invariant proteins is co-expressed with BARP as triple helical bundle structures on the surface of salivary gland forms, but is dispensable for parasite development within the tsetse vector

Trypanosoma brucei spp. develop into mammalian-infectious metacyclic trypomastigotes inside tsetse salivary glands. Besides acquiring a variant surface glycoprotein (VSG) coat, little is known about the metacyclic expression of invariant surface antigens. Proteomic analyses of saliva from T. brucei-infected tsetse flies identified, in addition to VSG and Brucei Alanine-Rich Protein (BARP) peptides, a family of glycosylphosphatidylinositol (GPI)-anchored surface proteins herein named as Metacyclic Invariant Surface Proteins (MISP) because of its predominant expression on the surface of metacyclic trypomastigotes. The MISP family is encoded by five paralog genes with >80% protein identity, which are exclusively expressed by salivary gland stages of the parasite and peak in metacyclic stage, as shown by confocal microscopy and immuno-high resolution scanning electron microscopy. Crystallographic analysis of a MISP isoform (MISP360) and a high confidence model of BARP revealed a triple helical bundle architecture commonly found in other trypanosome surface proteins. Molecular modelling combined with live fluorescent microscopy suggests that MISP N-termini are potentially extended above the metacyclic VSG coat, and thus could be tested as a transmission-blocking vaccine target. However, vaccination with recombinant MISP360 isoform did not protect mice against a T. brucei infectious tsetse bite. Lastly, both CRISPR-Cas9-driven knock out and RNAi knock down of all MISP paralogues suggest they are not essential for parasite development in the tsetse vector. We suggest MISP may be relevant during trypanosome transmission or establishment in the vertebrate's skin.

Early hepatic and peritoneal changes and immune response in goats vaccinated with a recombinant glutathione transferase sigma class and challenged with Fasciola hepatica

Changes and local immune response were evaluated in the peritoneal cell populations, duodenal lamina propria and liver from goats immunized with recombinant glutathione transferase sigma class (rFhGST-S1) during early stages of infection with Fasciola hepatica. Group 1 (n=7) was unimmunized and uninfected; group 2 (n=10) was immunized with adjuvant Quil A and infected; group 3 (n=10) was immunised with rFhGST-S1 and infected. Three goats from each group were killed at 7-9 days post-infection (dpi) to evaluate early changes and immune response. The remaining goats were killed at 15 weeks post-infection (wpi). rFhGST-S1 vaccination induced variable response: three goats showed low fluke burden at 15 wpi and two goats showed low hepatic damage at early infection stages. This response was associated to a severe infiltrate of eosinophils in peritoneal fluid and hepatic necrotic foci, high iNOS expression in peritoneal cells and abundant infiltrate of eosinophils surrounding hepatic migrating flukes. T lymphocyte subsets were found in the vicinity of necrotic areas but they were absent in the vicinity of migrating larvae. No significant variation for T cell subsets, except for CD4 and γδ T lymphocytes, that were higher in the Quil A group compared to the rFhGST-S1 group. Expression of IL4 and IFN-γ in the hepatic inflammatory infiltrates was very occasional.

Proteomic analyses of Caenorhabditis elegans dauer larvae and long-lived daf-2 mutants implicates a shared detoxification system in longevity assurance

The insulin/insulin-like growth factor-1 (IGF-1) signaling system is a public regulator of aging in the model animals Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus. For the first time, proteomic analyses of the environmentally resistant and 'nonaging' C. elegans dauer stage and long-lived daf-2 mutants has provided a unique insight into the protein changes which mediate survival against endogenously produced toxins. These changes support a diversion of energy consumption away from anabolic processes toward enhanced cellular maintenance and detoxification processes as previously described by the 'Green Theory of Aging'. Important components of this enhanced longevity system identified in this proteomics study include the alpha-crystallin family of small heat shock proteins, anti-ROS defense systems and cellular phase II detoxification (in daf-2 only). Among those proteins involved in phase II cellular detoxification that were significantly upregulated was a Pi-class glutathione transferase (GST) CE00302. Targeting this GST with RNAi revealed compensatory regulation within the Pi-class GSTs. Furthermore, a recombinant form of the GST protein was found to detoxify and/or bind short-chain aldehydic natural toxic products of lipid peroxidation and long-chained fatty-acids at physiologically relevant concentrations, which may indicate a role in longevity.

Heme transport and detoxification in nematodes: subproteomics evidence of differential role of glutathione transferases

In contrast to their mammalian hosts, parasitic nematodes are heme auxotrophs and require pathways for the uptake and transport of exogenous heme for incorporation into hemoproteins. Phase II detoxification Nu-class glutathione transferase (GST) proteins have a proposed role as heme-binding ligandins in parasitic nematodes. The genome-verified free-living nematode Caenorhabditis elegans also cannot synthesize heme and is an ideal functional genomics model to delineate the role of individual nematode GSTs in heme trafficking and heme detoxification. In this study, C. elegans was exposed to externally controlled heme concentrations ranging from 20-fold suboptimal growth levels to 10-fold supra-optimal growth levels to mimic fluctuations in blood- and tissue-feeding parasitic cousins from the same nematode group. A new heme-responsive GST (GST-19) was identified by subproteomics approaches. Functional characterization of this and two other C. elegans GSTs revealed that they all have high affinity for heme compounds similar to mammalian soluble heme carrier proteins such as HBP23 ( K d approximately 10 (-8) M). In the genomics-predicted absence of orthologous mammalian soluble heme-binding proteins in nematodes, we propose that Nu-class GSTs are candidates in the cellular processing of heme compounds. Toxic heme binding may be coupled to enzymatic protection from its breakdown as several GSTs possess glutathione peroxidase activity.

A proteomics approach to quantify protein levels following RNA interference: case study with glutathione transferase superfamily from the model metazoan Caenorhabditis elegans

Loss-of-function phenotypic analysis via interference RNA (RNAi) technology is a revolutionary approach to assigning gene function. While transcript-based methodologies commonly validate RNAi gene suppression investigations, protein-based validation is less developed. This report illustrates the potential for two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2-DE) and gel analysis to quantify protein levels following RNAi. This case study involves three glutathione transferase (GST) genes targeted by RNAi from the model organism Caenorhabditis elegans.