Cristina Toscano Fonseca

Schistosoma Tegument Proteins in Vaccine and Diagnosis Development: An Update

The development of a vaccine against schistosomiasis and also the availability of a more sensitive diagnosis test are important tools to help chemotherapy in controlling disease transmission. Bioinformatics tools, together with the access to parasite genome, published recently, should help generate new knowledge on parasite biology and search for new vaccines or therapeutic targets and antigens to be used in the disease diagnosis. Parasite surface proteins, especially those expressed in schistosomula tegument, represent interesting targets to be used in vaccine formulations and in the diagnosis of early infections, since the tegument represents the interface between host and parasite and its molecules are responsible for essential functions to parasite survival. In this paper we will present the advances in the development of vaccines and diagnosis tests achieved with the use of the information from schistosome genome focused on parasite tegument as a source for antigens.

IL-12 and TNF-α production by dendritic cells stimulated with Schistosoma mansoni schistosomula tegument is TLR4- and MyD88-dependent

Schistosoma mansoni schistosomula are the most susceptible parasite life stage to host immune system attack. Complex host-parasite interactions take place on Schistosoma tegument, which is a unique double membrane structure involved in nutrition and immune evasion. Herein, we have demonstrated that schistosomula tegument (Smteg) activates Dendritic cells to produce IL-12p40, TNF-alpha and also to up-regulate the co-stimulatory molecules CD40 and CD86. Moreover, using DCs derived from MyD88-, TLR2-, TLR4- and TLR9-deficient mice we have shown that the ability of Smteg to activate DCs to produce IL-12 and TNF-alpha involves TLR4/Smteg interaction and MyD88 signaling pathway. Finally, our findings lead us to conclude that TLR4 is a key receptor involved in Smteg induction of pro-inflammatory cytokines.

Immunization with newly transformed Schistosoma mansoni schistosomula tegument elicits tegument damage, reduction in egg and parasite burden

The surface of the schistosomula is an important target for host immune system attack because the tegument represents the interface between host and parasite and thus is a potential candidate for the development of new intervention strategies. In this study, we evaluated the ability of schistosomula tegument (Smteg) to induce protection in mice. Immunization of mice with Smteg together with Freund adjuvant induced a Th1 type of immune response associated with a significant reduction in worm burden (43–48%), eggs trapped in the liver (65%), eggs eliminated in the faeces (59–60%) and granuloma number (41%). Lastly, during an in vitro study, worms from mice immunized with Smteg showed damage in the adult worm tegument and impaired egg laying.

Política, atores e interesses no processo de mudança institucional: a criação do Ministério da Saúde em 1953

This analysis of the 1953 creation of the Ministry of Health identifies the main actors involved, their interests, and the strategies they employed to reach their goals and influence the process of institutional change. Placing the process within the context of the eras specific political characteristics, the article identifies the predominant decision-making arena as well as the political variables that influenced the emergence of this new, autonomous government agency for public health.

Booster dose after 10 years is recommended following 17DD-YF primary vaccination

A single vaccination of Yellow Fever vaccines is believed to confer life-long protection. In this study, results of vaccinees who received a single dose of 17DD-YF immunization followed over 10 y challenge this premise. YF-neutralizing antibodies, subsets of memory T and B cells as well as cytokine-producing lymphocytes were evaluated in groups of adults before (NVday0) and after (PVday30-45, PVyear1-4, PVyear5-9, PVyear10-11, PVyear12-13) 17DD-YF primary vaccination. YF-neutralizing antibodies decrease significantly from PVyear1-4 to PVyear12-13 as compared to PVday30-45, and the seropositivity rates (PRNT≥2.9Log10mIU/mL) become critical (lower than 90%) beyond PVyear5-9. YF-specific memory phenotypes (effector T-cells and classical B-cells) significantly increase at PVday30-45 as compared to naïve baseline. Moreover, these phenotypes tend to decrease at PVyear10-11 as compared to PVday30-45. Decreasing levels of TNF-α+ and IFN-γ+ produced by CD4+ and CD8+ T-cells along with increasing levels of IL-10+CD4+T-cells were characteristic of anti-YF response over time. Systems biology profiling represented by hierarchic networks revealed that while the naïve baseline is characterized by independent micro-nets, primary vaccinees displayed an imbricate network with essential role of central and effector CD8+ memory T-cell responses. Any putative limitations of this cross-sectional study will certainly be answered by the ongoing longitudinal population-based investigation. Overall, our data support the current Brazilian national immunization policy guidelines that recommend one booster dose 10 y after primary 17DD-YF vaccination.

Molecular characterization of the Corynebacterium pseudotuberculosis hsp60-hsp10 operon, and evaluation of the immune response and protective efficacy induced by hsp60 DNA vaccination in mice

BackgroundHeat shock proteins (HSPs) are important candidates for the development of vaccines because they are usually able to promote both humoral and cellular immune responses in mammals. We identified and characterized the hsp60-hsp10 bicistronic operon of the animal pathogen Corynebacterium pseudotuberculosis, a Gram-positive bacterium of the class Actinobacteria, which causes caseous lymphadenitis (CLA) in small ruminants.FindingsTo construct the DNA vaccine, the hsp60 gene of C. pseudotuberculosis was cloned in a mammalian expression vector. BALB/c mice were immunized by intramuscular injection with the recombinant plasmid (pVAX1/hsp60).ConclusionThis vaccination induced significant anti-hsp60 IgG, IgG1 and IgG2a isotype production. However, immunization with this DNA vaccine did not confer protective immunity.

Schistosoma mansoni schistosomula tegument (Smteg) immunization in absence of adjuvant induce IL-10 production by CD4+ cells and failed to protect mice against challenge infection.

The Schistosoma mansoni tegument interaction with the immune system plays a key role in disease establishment or elimination. We have recently demonstrated that S. mansoni schistosomula tegument (Smteg) is able to activate innate immune response and to induce protective immunity in a vaccine formulation with Freunds adjuvant. In this work, we evaluated the ability of Smteg to elicit protection in the absence of adjuvant. Smteg mice immunization resulted in significant antibody production, increased percentage of CD4+IFN-g+ and CD4+IL-10+ cells in spleen and increased production of IFN-g and IL-10 by spleen cells, but failed to reduce parasite burden, female fecundity and morbidity. We also demonstrated that BMDC stimulation with Smteg resulted in significant IL-10 production. Our results demonstrate that Smteg has immune modulatory proprieties.

Antibodies are involved in the protective immunity induced in mice by Schistosoma mansoni schistosomula tegument (Smteg) immunization.

The Schistosoma mansoni schistosomula tegument (Smteg) plays an important role in triggering the host immune response and mice immunization with Smteg formulated with Freunds adjuvant or alum + CpG induce partial protection against S. mansoni infection associated with an increased antibody production. In this study, we investigated the role of these antibodies in parasite killing both in vitro and in vivo. We demonstrated that these antibodies were able to bind to the surface of S. mansoni recently transformed schistosomula and that these antibodies significantly increase the percentage of schistosomula killed in vitro by complement activation. Passive transference of immune sera decreased the parasite burden and the number of eggs trapped in the organs of mice that received sera containing anti‐Smteg antibodies. These results demonstrate that antibodies specific to surface tegumental antigens are involved in parasite elimination in mice immunized with Smteg.

The Use of Reverse Vaccinology and Molecular Modeling Associated with Cell Proliferation Stimulation Approach to Select Promiscuous Epitopes from Schistosoma mansoni

Schistosomiasis remains an important parasitic disease that affects millions of individuals worldwide. Despite the availability of chemotherapy, the occurrence of constant reinfection demonstrates the need for additional forms of intervention and the development of a vaccine represents a relevant strategy to control this disease. With the advent of genomics and bioinformatics, new strategies to search for vaccine targets have been proposed, as the reverse vaccinology. In this work, computational analyses of Schistosoma mansoni membrane proteins were performed to predict epitopes with high affinity for different human leukocyte antigen (HLA)-DRB1. Ten epitopes were selected and along with murine major histocompatibility complex (MHC) class II molecule had their three-dimensional structures optimized. Epitope interactions were evaluated against murine MHC class II molecule through molecular docking, electrostatic potential, and molecular volume. The epitope Sm141290 and Sm050890 stood out in most of the molecular modeling analyses. Cellular proliferation assay was performed to evaluate the ability of these epitopes to bind to murine MHC II molecules and stimulate CD4+ T cells showing that the same epitopes were able to significantly stimulate cell proliferation. This work showed an important strategy of peptide selection for epitope-based vaccine design, achieved by in silico analyses that can precede in vivo and in vitro experiments, avoiding excessive experimentation.

Evaluation of the use of C-terminal part of the Schistosoma mansoni 200 kDa tegumental protein in schistosomiasis diagnosis and vaccine formulation

Schistosoma mansoni tegument is involved in essential functions for parasite survival and represents a target for screening candidates for vaccine and diagnosis. Our group using reverse vaccinology selected six candidates, previously demonstrated by proteomics studies to be expressed in the parasite tegument, among them was Sm200. In this work we have cloned and expressed a recombinant form of Sm200 C-terminal (1069-1520) region. The efficacy of rSm200 (1069-1520) in the diagnosis of schistosomiasis and in the formulation of a vaccine against S. mansoni was assessed respectively in an ELISA based diagnostic assay and immunization protocols in mice. Significant differences between non-infected and acutely infected or chronically infected animals were observed and no cross-recognition was observed with sera from Ascaris suum or Ancylostoma ceylanicum infected mice. rSm200-ELISA test could also discriminate infected individuals from healthy donors not living in endemic area for schistosomiasis but failed to discriminate between individuals from a low endemic area for schistosomiasis known to have positive or negative stools after examination. Recombinant Sm200 also failed to induce protection against schistosomiasis, demonstrating that the C-terminal part of Sm200 is unable to induce protective immune response in mice. Therefore rSm200 (1069-1520)-ELISA represents an important tool to be used in the diagnosis of schistosomiasis.