Serum cytokines of the 20 Krad-irradiated S. mansoni cercariae vaccinated, primary and superinfected Cercopethicus aethiops aethiops

Vaccines for Human Schistosomiasis: Recent Progress, New Developments and Future Prospects

Schistosomiasis, caused by human trematode blood flukes (schistosomes), remains one of the most prevalent and serious of the neglected tropical parasitic diseases. Currently, treatment of schistosomiasis relies solely on a single drug, the anthelmintic praziquantel, and with increased usage in mass drug administration control programs for the disease, the specter of drug resistance developing is a constant threat. Vaccination is recognized as one of the most sustainable options for the control of any pathogen, but despite the discovery and reporting of numerous potentially promising schistosome vaccine antigens, to date, no schistosomiasis vaccine for human or animal deployment is available. This is despite the fact that Science ranked such an intervention as one of the top 10 vaccines that need to be urgently developed to improve public health globally. This review summarizes current progress of schistosomiasis vaccines under clinical development and advocates the urgent need for the establishment of a revolutionary and effective anti-schistosome vaccine pipeline utilizing cutting-edge technologies (including developing mRNA vaccines and exploiting CRISPR-based technologies) to provide novel insight into future vaccine discovery, design, manufacture and deployment.

Proteomic analysis of schistosomiasis japonica vaccine candidate antigens recognized by UV-attenuated cercariae-immunized porcine serum IgG2

Many studies have showed that the radiation-attenuated cercariae (RAC) vaccine could induce the high protection of laboratory animals to resist the schistosoma infection by cellular and humoral mechanism. Here, we aimed to identify possible vaccine antigens by using specific IgG2 antibody from RAC-vaccinated pigs or vaccination and challenge pigs. The antigens from the schistosomal soluble worm antigen preparation (SWAP) recognized by the porcine IgG2 antibody were obtained using immunoprecipitation technique. These antigens were separated by 2-D electrophoresis, and 116 spots were successfully identified by MALDI-TOF MS from about 400 putative spots in gels. Among these spots, 113 spots could match to the Schistosoma japonicum. These identified proteins in four groups were classified by Gene Ontology (Go) database, and the mainly functions of these proteins were involved in binding, catalytic activity (thioredoxin peroxidase-2, et al.), signal transduction class (MAP Kinase, et al.), cell process (the heat shock 70-kDa protein 9B, et al.), and the intracellular component (tektin, et al.). Our methods suggested that it was possible to pull-down the interesting proteins recognized by specific antibodies. Our results may provide new clues for exploring the mechanism of high protection induced by RAC and shed some light on the research for anti-schistosomiasis japonica vaccine.

Levels of certain tumor markers as differential factors between bilharzial and non-biharzial bladder cancer among Egyptian patients

BACKGROUND/OBJECTIVE

Bladder cancer is the commonest type of malignant tumors as a result of schistosomaisis which is a major healthy problem in many subtropical developing countries. The aim of this study is to comparatively elucidate the underlying biochemical tumor markers in schistosomal bladder cancer versus non-schistosomal bladder cancer when compared to normal healthy ones.

METHODS

This work was performed on tissue specimens from total 25 patients and serum samples from total 30 patients versus ten healthy individuals served as control. The investigated parameters in serum are: xanthine oxidase (XO), fructosamine, lactate dehydrogense (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total proteins, essential and non- essential amino acids profile, hydroxyproline, total immunoglobulin E (IgE) and tumor necrosis factor alpha (TNF-α). In addition, the current investigation also extended to study some markers in tumor bladder tissues including, pyruvate kinase enzyme (PK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT).

RESULTS

Results showed that biharzial bladder cancer patients recored more significant elevation in serum XO, fructosamine, LDH, AST, ALT, hydroxyproline, IgE and TNF-α than in bladder cancer patients when compared to control ones. While, in tissues there were significant increase in PK, LDH, AST & ALT activities of schistosomal bladder cancer than in bladder cancer as compared to control healthy patients.

CONCLUSIONS

It could be concluded that, bilharzial and non-bilharzial bladder cancer showed distinct biochemical profile of tumor development and progression which can be taken into consideration in diagnosis of bladder cancer.

Immune events associated with high level protection against Schistosoma japonicum infection in pigs immunized with UV-attenuated cercariae

Background

The vaccination of radiation-attenuated Schistosoma japonicum cercariae can induce effective protection in artiodactyl, but the immune events related to protective immunity are not fully understood. To provide a paradigm for a human recombinant antigen vaccine, we have undertaken a vaccination and challenge experiment in pigs, which was recognized as an appropriate animal model in this type of study because of their similarity to human in immunology, and investigated the relative immune events induced by the radiation-attenuated S. japonicum cercariae.

Methods and Findings

We found that pigs immunized once with 400 µw UV-irradiated cercariae exhibited 63.84% and 71.82% reductions in worm burden and hepatic eggs respectively. Protective immunity in vaccinated pigs was associated with high level productions of IgM, total IgG, IgG1 and IgG2; IgG2 was significantly increased in the acute infection. IFN-γ levels could be elicited by immunization. At week 6 post-infection, IFN-γ, IL-4 and IL-10 levels also showed a dramatic rise synchronously in vaccinated pigs. Moreover, the granzyme b, nk-lysin, ifnγ, il4 and il10 mRNA levels in early skin-draining lymph nodes of immunized pigs were higher than those in pigs with non-irradiated cercariae infection. In addition, cytotoxicity-related genes in the mesenteric lymph nodes were significantly upregulated in vaccinated pigs in the acute infection.

Conclusion/Significance

Our results demonstrated that IFN-γ and IgG2 antibody production, as well as genes related to cytotoxicity are associated with the high level protection induced by UV-irradiated Schistosoma japonicum vaccine. These findings indicated that optimal vaccination against S. japonicum required the induction of IFN-γ, IgG2 antibody related to Th1 responses and cytotoxicity effect.

Schistosoma japonicum: proteomics analysis of differentially expressed proteins from ultraviolet-attenuated cercariae compared to normal cercariae

Schistosomiasis is considered the most important human helminthiasis in terms of morbidity and mortality. In this study, comparative soluble proteomic analysis of normal cercariae and ultraviolet-irradiated attenuated cercariae (UVAC) from Schistosoma japonicum were carried out in view of the high efficiency of irradiation-attenuated cercariae vaccine. The results revealed that some proteins showed significant differential expression in the parasite after treatment with ultraviolet light. Total 20 protein spots were identified by mass spectrometry, corresponded to five groups according to their functions in the main that were structural and motor proteins (actin, et al.), energy metabolism associated enzymes (glyceraldehydes-3-phosphage dehydrogenase, et al.), signaling transduction pathway-associated molecules (14-3-3 protein, et al.), heat shock protein families (HSP 70 family, et al.), and other functional proteins (20S proteasome). Furthermore, our results indicated that the differential expression of the proteins by ultraviolet irradiation may be, at least partially, acquired by regulating the mRNA levels of corresponding proteins. These results may provide new clues for further exploring the mechanism of protective immunity induced by UVAC and may shed some light on the development of vaccines against schistosomiasis.

Current status of vaccines for schistosomiasis

Schistosomiasis, caused by trematode blood flukes of the genus Schistosoma, is recognized as the most important human helminth infection in terms of morbidity and mortality. Infection follows direct contact with freshwater harboring free-swimming larval (cercaria) forms of the parasite. Despite the existence of the highly effective antischistosome drug praziquantel (PZQ), schistosomiasis is spreading into new areas, and although it is the cornerstone of current control programs, PZQ chemotherapy does have limitations. In particular, mass treatment does not prevent reinfection. Furthermore, there is increasing concern about the development of parasite resistance to PZQ. Consequently, vaccine strategies represent an essential component for the future control of schistosomiasis as an adjunct to chemotherapy. An improved understanding of the immune response to schistosome infection, both in animal models and in humans, suggests that development of a vaccine may be possible. This review considers aspects of antischistosome protective immunity that are important in the context of vaccine development. The current status in the development of vaccines against the African (Schistosoma mansoni and S. haematobium) and Asian (S. japonicum) schistosomes is then discussed, as are new approaches that may improve the efficacy of available vaccines and aid in the identification of new targets for immune attack.

The development of hepatic granulomas in 20 Krad irradiated Schistosoma mansoni cercaria vaccinated grivet monkeys (Cercopithecus aethiops aethiops)

The absence of appropriate animal models is a challenge for those designing anti-schistosome vaccines. In order to observe the development of hepatic granulomata, 20 Krad irradiated cercaria vaccinated grivet monkeys (Cercopithecus aethiops aethiops) were experimentally infected with Schistosoma mansoni. Most human clinical manifestations of schistosomiasis were noted in the infected monkeys. Intraperitonial immunization with 20 Krad irradiated cercaria resulted in a relatively less granulomatous reaction and lower egg mass (P<0.05) than in the controls. The mean total adult worms and egg production was also lower in the vaccinated group. This study underlines the significant role of irradiated cercariae vaccination on the establishment of female adults and consequent reduction of pathology in the grivet Cercopithecus aethiops aethiops.