The Immunological Properties of Recombinant Multi-Cystatin-Like Domain Protein From Trichinella Britovi Produced in Yeast

Immunomodulatory in vitro effects of Trichinella cystatin-like protein on mouse splenocytes

Trichinella parasites have developed specific mechanisms allowing successful completion of their life cycle. These mechanisms are in a great part involved in immunomodulation and studying them may provide a valuable insight into the functioning of the immune system. Trichinella products may be also used as potential therapeutic agents to treat immune diseases. This study investigates the immunomodulatory potential of recombinant multi cystatin-like protein (CLP) derived from T. britovi to determine whether CLP has anti-inflammatory properties in vitro. CLP is a highly antigenic glycoprotein present in Trichinella excetory-secretory (ES) products. AlphaFold structure prediction confirms that it consists of three type-two cystatin-like domains. Mouse splenocytes were stimulated in vitro with lipopolysaccharide (LPS) and co-stimulated with recombinant CLP. The culture supernatants were collected and tested for secreted cytokine levels using ELISA. CLP was found to reduce LPS-induced secretion of inflammatory cytokines TNFα and IL-6. On the contrary, in some experimental groups, co-stimulation with CLP resulted in increased secretion of the regulatory cytokine IL-10. The obtained results indicate that CLP has anti-inflammatory properties and future research on its function is advisable, specifically in the context of the therapy of inflammatory disorders.

Th1 and Th2 epitopes of Cowdria polymorphic gene 1 of Ehrlichia ruminantium

Cowdria polymorphic gene 1 (cpg1, Erum2510, ERUM_RS01380) has been shown to induce 30% and 100% protection in sheep immunised by deoxyribonucleic acid (DNA) prime combined with DNA boost and DNA prime combined with protein boost, respectively, against heartwater infection via needle challenge. To localise its antigenic regions for inclusion in a multi-epitope DNA vaccine against heartwater, Erum2510 was cleaved into five overlapping subfragments. These subfragments were expressed individually in an Escherichia coli host expression system and evaluated for their ability to induce proliferative responses, Th1 and Th2 cytokines (interferon gamma [IFN-γ] and interleukin 4 [IL-4]) via enzyme-linked immunospot (ELISpot), quantitative real time polymerase chain reaction (qRT-PCR) and flow cytometry. Recombinant (r)proteins 3 and 4 were shown to induce immunodominant Th1 and Th2 immune responses characterised by the secretion of effector cytokines IFN-γ and IL-4 in addition to differential messenger ribonucleic acid (mRNA) expression of tumour necrosis factor (TNF), IL-2, IL-1, IL-18, IL-10, transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and inducible nitric oxide synthase (iNOS). Thirty-seven overlapping synthetic peptides (16 mer) spanning the lengths of these immunodominant rproteins were synthesised and assayed. A peptide pool comprising p9 and p10 derived from rprotein 3 induced a Th1-biased immune response. A peptide pool comprising p28 and p29 derived from rprotein 4 induced a mixed Th1 and Th2 immune response characterised by secretion of IFN-γ and differential mRNA expression of IL-1, IL-2, IL-10, IL-12, iNOS, TGF, TNF and GM-CSF. Only one of the peptides (p29) induced secretion of IL-4. Phenotypic analysis showed significant activation of cluster of differentiation 8+ (CD8+), cluster of differentiation 4+ (CD4+) and B+ lymphocyte populations. Findings suggest that Erum2510 rproteins and synthetic peptides can induce both cellular and humoral immune responses, thereby implicating their importance in protection against heartwater.Contribution: This study will facilitate the design of an effective multi-epitope DNA vaccine against heartwater that will contribute to control this economically important disease in sub-Saharan Africa and beyond.

Immunoproteomic Analysis of Trichinella britovi Proteins Recognized by IgG Antibodies from Meat Juice of Carnivores Naturally Infected with T. britovi

Infection with Trichinella nematodes elicits non-specific and specific immune responses; these depend on the dose of infection, the nematode, and the host species. Few studies have examined the presence of specific antibodies against Trichinella spp. in the meat juice of wild animals. The aims of the study were to determine the prevalence of antibodies against Trichinella spp. in meat juice and to identify the specific proteins reacting with the meat juice from free-living carnivores naturally infected with the parasite. Meat juice samples were taken from foxes, badgers, raccoon dogs, and martens and tested with indirect ELISA. Antibodies against Trichinella spp. were detected in 10% of foxes and 46% of raccoon dogs. The ELISA results were confirmed by immunoblot, which revealed different protein patterns in meat juice from red foxes, raccoon dogs, and badgers. The most frequently observed bands were sent for further analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the detection of Trichinella britovi immunogenic proteins. The results confirm the presence of proteins such as serine protease and heat shock proteins associated with Trichinella infection. These findings provide that meat juice is a useful matrix for proteomic analysis.

Trichinella britovi recombinant proteins produced in Pichia pastoris expression system for specific IgG antibody detection in the sera of mice and pigs infected with Trichinella spp

Trichinellosis, a disease caused by infection with Trichinella spp, poses an economic problem in the animal sector and a recurrent health problem for humans. Discovering the new diagnostic tests may be achieved by identification and production of species- and stage-specific recombinant proteins of Trichinella genus which are recognized by the host antibodies after infection. In this study the T. britovi proteins identified earlier in excretory-secretory (ES) products: CTRL, ES21 and HSP20, were cloned and produced using a eukaryotic Pichia pastoris system. Their immunodiagnostic properties were verified by measuring the abundance of specific IgG antibodies in sera from mice and pigs experimentally infected with T. britovi or T. spiralis. The rTbCTRL and the rTbES21 proteins were more effectively produced and stable than rTbHSP20. The most sensitive protein for serodiagnostic purposes occurred to be CTRL; anti-rTbCTRL IgG level increased at 41 days post infection (dpi) in pigs infected with T. britovi and 45 dpi for those infected with T. spiralis. The rTbES21 protein was the most specific for the T. britovi species, as no antibody titers were observed in pigs infected with T. spiralis. Following the multiple-antigen strategy, the combination of rTbCTRL + rTbES21 was applied in ELISA, but no significant difference in IgG level was detected in the tested conditions.

Proteomics of Gnathostomiasis: A Way Forward for Diagnosis and Treatment Development

Gnathostoma spinigerum is the most common cause of gnathostomiasis in humans. It has a complex life cycle, which requires two intermediate hosts and a definitive host, and poses a high risk for zoonosis. Definitive prognosis of gnathostomiasis relies mainly on the isolation of advanced-stage larvae (aL3), which is very challenging especially if the aL3 is sequestered in difficult-to-reach organs. There is also a lack of a confirmatory diagnostic test for gnathostomiasis. With the ongoing advancement of proteomics, a potential diagnostic approach is underway using immunoproteomics and immunodiagnostics. In addition to this, the employment of mass spectrometry could further elucidate not only understanding the biology of the parasite but also determining potential targets of prospective drugs and vaccines. This article reports the past, present, and future application of proteomics in the study of gnathostomiasis.

Exploiting the potential of 2D DIGE and 2DE immunoblotting for comparative analysis of crude extract of Trichinella britovi and Trichinella spiralis muscle larvae proteomes

The Trichinella genus poses an interesting puzzle for researchers, having diverged very early in the evolution of the nematodes. The Trichinella spiralis proteome is a cosmopolitan and well-studied model of Trichinella; however, Trichinella britovi also circulates in the sylvatic environment and both species infect humans, resulting in the development of trichinellosis. Few experiments have examined the proteins belonging to the T. britovi proteome. The aim of the present study was to compare the protein expression profiles of crude extracts of T. spiralis and T. britovi muscle larvae using a highly-sensitive two-dimensional differential in-gel electrophoresis (2D DIGE) technique coupled with 2DE immunoblotting. Selected immunoreactive protein spots were then identified by liquid chromatography coupled with mass spectrometry analysis (LC-MS/MS), and their function in Trichinella and the host-parasite interaction was determined by gene ontology analysis. Spots common to both T. spiralis and T. britovi, spots with different expressions between the two and spots specific to each species were labelled with different cyanine dyes. In total, 196 protein spots were found in both proteomes; of these 165 were common, 23 expressed exclusively in T. spiralis and 8 in T. britovi. A comparative analysis of volume ratio values with Melanie software showed that among the common spots, nine demonstrated higher expression in T. spiralis, and 17 in T. britovi. LC-MS/MS analysis of 11 selected spots identified 41 proteins with potential antigenic characteristics: 26 were specific for T. spiralis, six for T. britovi, and eight were found in both proteomes. Gene Ontology analysis showed that the identified T. spiralis proteins possess hydrolytic endopeptidase, endonuclease and transferase activities. Similarly, most of the T. britovi proteins possess catalytic activities, such as lyase, hydrolase, isomerase and peptidase activity. The applied 2D DIGE technique visualized Trichinella spp. protein spots with different molecular weights or isoelectric point values, as well as those with different expression levels. The identified immunoreactive proteins participate in multiple processes associated with host muscle cell invasion and larval adaptation to the host environment. Their reactivity with the host immune system makes them possible candidates for the development of a novel trichinellosis diagnostic test or vaccine against helminthiasis caused by T. spiralis or T. britovi.

Immunoproteomic analysis of Trichinella spiralis and Trichinella britovi excretory-secretory muscle larvae proteins recognized by sera from humans infected with Trichinella

The present study compares the immunogenic patterns of muscle larvae excretory-secretory proteins (ML E-S) from T. spiralis and T. britovi recognized by Trichinella-infected human sera. Samples were analyzed using two-dimensional electrophoresis (2-DE) coupled with 2D-immunoblot and liquid chromatography-tandem mass spectrometry LC-MS/MS analysis, two ELISA procedures and a confirmatory 1D-immunoblot test. Sera were obtained from nine patients with a history of ingestion of raw or undercooked meat who presented typical clinical manifestations of trichinellosis and from eleven healthy people. Specific anti-Trichinella IgG antibodies were detected in all samples tested with the Home-ELISA kits, but in only four samples for the commercially-available kit. The 1D-immunoblot results indicated that all nine serum samples were positive for T. spiralis ML E-S antigens, expressed as the presence of specific bands. In contrast, eight of the serum samples with T. britovi E-S ML antigens were positive, with one serum sample taken from a patient at 33dpi (days post infection) being negative. To identify immunoreactive proteins that are specifically recognized by host antibodies, both species of ML E-S proteins were subjected to 2D-immunoblotting with human serum taken at 49 dpi. The sera recognized 22 protein spots for T. spiralis and 18 for T. britovi in 2D-immunoblot analysis. Their molecular weights (MW) ranged from 50 to 60 kDa. LC-MS/MS analysis identified both common and specifically-recognized immunoreactive proteins: transmembrane serine protease 9, serine protease, antigen targeted by protective antibodies and Actin-1 partial were shared for both Trichinella species; hypothetical protein T01_7775 and P49 antigen, partial those specific to T. spiralis; deoxyribonuclease-2-alpha and hypothetical protein T03_17187/T12_7360 were specific to T. britovi. Our results demonstrate the value of 2-DE and 2D-immunblot as versatile tools for pinpointing factors contributing to the parasite-host relationship by comparing the secretomes of different Trichinella species.

Immunization with a Recombinant Protein of Trichinella britovi 14-3-3 Triggers an Immune Response but No Protection in Mice

14-3-3 proteins are present in all eukaryotic organisms and are ubiquitously expressed in a broad range of tissues and cellular compartments. They are regulatory adapter proteins that play key roles in a variety of signaling pathways, and have been proposed as suitable targets for the control and detection of certain parasites. Trichinella britovi is a widely-distributed parasitic nematode, transmitted through ingestion of meat products containing invasive larvae. The present study describes the cloning and expression of Tb14-3-3, and investigates the immunological and protective potential of the recombinant protein. Immunization of mice with rTb14-3-3 triggered an IgG response, and significant differences, in the profiles of secreted cytokines observed in vitro, between experimental groups. Nonetheless, neither specific antibodies, nor increased secretion of IFNγ, IL-4, and IL-10 cytokines, conferred greater protection against infection. No reduction in larval burden was observed during recovery at 48 dpi. Additionally, rTb14-3-3 was not recognized by sera from the infected control mice, except for one, suggesting some mismatch between native and recombinant Tb14-3-3 antigenic sites. Therefore, before 14-3-3 can be considered a potential tool for Trichinella detection and vaccination, more research regarding its target proteins, and actual specific function, is needed.