Project description:Schistosoma mansoni is the causative agent of schistosomiasis, an endemic neglected tropical disease that affects the human population. Recently, newer versions of the genome and transcriptome have been published, with the Sanger Institute leading both the original publication of the genome as well as the further upgrade. However, little is known about the regulatory elements found in the genome, i.e. promoters. Identification of these elements is key for the understanding of mechanisms of regulation of gene expression in this parasitic helminth.
Project description:Background: The parasitic trematode Schistosoma mansoni is one of the major causative agents of human schistosomiasis, which afflicts 200 million people worldwide. Praziquantel is still the only drug used for schistosomiasis treatment and reduction in drug efficiency has prompting the search for new therapeutic compounds against this disease. Our group has demonstrated that heme crystallization into hemozoin (Hz) within S. mansoni gut is a major heme detoxification route involving lipid droplets in this process and acting as a potential chemotherapeutical target. In the present work, we investigated the effects of the antimalarial quinine (QN) in a murine schistosomiasis model by using a combination of biochemical, cell biology and molecular biology approaches. Methodology/Principal Findings: Treatment of S. mansoni-infected female Swiss mice with daily intraperitoneal injections of QN (75mg/kg/day) from 11th to 17th day after infection decreased not only total, males and females worm burden (46.2 %-51.0 %), eggs production, but also the granulomatous reaction to parasite eggs trapped in the liver. These effects correlated with a significant impairment of Hz production (40%) specifically in S. mansoni females, being parallel to remarkable ultrastructural changes in female worms, particularly in the gut epithelium. Microarray gene expression analysis indicated that QN treatment increased the expression of transcripts related to musculature, protein synthesis and repair mechanisms. Conclusions: The overall significant reduction in several disease burden parameters by QN treatment indicates that interference of Hz formation in S. mansoni is a valid chemotherapeutical target for development of new antischistosomal drugs.
Project description:Schistosoma mansoni is the major causative agent of schistosomiasis in the Americas. This parasite takes advantage from host signaling molecules such as cytokines and hormones to complete its development inside the host. TNF-α is the most important cytokine involved in the inflammatory response when cercaria, the infective stage, penetrates the human skin and a severe inflammatory response is started. In this work the authors describe the complete sequence of a possible TNF-α receptor in S. mansoni and detect that the receptor is most highly expressed in cercaria among all life cycle stages. In an attempt to mimic the situation at the site of skin penetration cercariae have been mechanically transformed in vitro into schistosomula and immediately exposed to human TNF-α . Exposure of these early schistosomula to the human hormone caused a large-scale change in the expression of parasite genes. Exposure of adult worms to human TNF-α caused gene expression changes as well, although the set of parasite altered genes was entirely different from that of schistosomula. This work increases the number of known signaling pathways of the parasite, and opens new perspectives into understanding the molecular components of TNF-α response as well as possibly interfering with parasite-host interaction.
Project description:Using a hamster final-host model, we dissected molecular events following Schistosoma mansoni infection in the liver - the organ most severely affected in schistosomiasis patients. Employing Tandem Mass Tag (TMT)-based proteomics, we studied alterations in liver proteins in response to various infection modes and genders.
Project description:Schistosomiasis continues to be a significant public health problem1. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of S. mansoni. Our group recently identified Sm29, an antigen that is predominantly recognized by IgG1 and IgG3 antibodies of resistant patients2. In the present study, we show that Sm29 is located on the surface of adult worms and lung-stage schistosomula. Immunization of mice with recombinant (r) Sm29 engendered 51% reduction in adult worm burdens, 60% reduction in intestinal eggs and 55% reduction in liver granulomas. Protective immunity in mice was associated with high titers of specific IgG1 and IgG2a and elevated production of IFN-γ, TNF-α and IL-12. Further, cellular responses of infected schistosomiasis patients to rSm29 consisted of elevated IFN-γ and an absence of IL-5. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to control mice revealed a significant (q< 0.01) down-regulation of 498 genes, while no up-regulation was detected. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals suggesting that under immune attack schistosomes reduce the expression of critical surface proteins. This study demonstrates that the membrane-bound Sm29 protein is a new molecule that has great potential as a vaccine candidate against schistosomiasis. Keywords: Schistosoma mansoni gene expression in vaccinated mice
Project description:Schistosomiasis is a chronic neglected tropical disease caused by digenetic parasitic flatworms of the genus Schistosoma. The disease is estimated to affect over 206 million people, the majority of whom live in Africa where Schistosoma mansoni and Schistosoma japonicum are the major causative agents. While a number of drugs have been used to treat schistosomiasis, praziquantel (PZQ) is the only one that is widely available, relatively cheap, and easy to use. The reliance on a single drug for the treatment of such a prevalent disease is a cause for concern due to the potential for resistance to render PZQ ineffective. In this study we examine the transcriptome of three generations of a laboratory strain of S. mansoni (PR1) whose susceptibility to PZQ has been diminished across 9 passages through exposure to increasing sub-lethal doses of the drug. Miracidial susceptibility was significantly reduced after exposure to 2 x 50 mg/Kg PZQ during the first passage. Susceptibility of worms in vivo was first assessed during passage 5 when mice infected with PZQ-selected schistosomes were dosed with a lethal dose of 3 x 300 mg/Kg PZQ resulting in only a 10% reduction in worm number compared to control treatment. The emergence of reduced sensitivity was marked by a shift in sex ratio from a predominantly male to female population, a reduction in the length of females and ultimately the loss of the PZQ-selected line after passage 9, perhaps due to a selection induced fitness cost. Analysis of differentially regulated transcripts did not suggest that any particular gene product or pathway was associated with drug resistance suggesting either a loss of function mutation to a single gene or an epistatic interaction of multiple gene products.
Project description:Schistosoma mansoni is the major causative agent of schistosomiasis in the Americas. This parasite takes advantage from host signaling molecules such as cytokines and hormones to complete its development inside the host. TNF-α is the most important cytokine involved in the inflammatory response when cercaria, the infective stage, penetrates the human skin and a severe inflammatory response is started. In this work the authors describe the complete sequence of a possible TNF-α receptor in S. mansoni and detect that the receptor is most highly expressed in cercaria among all life cycle stages. In an attempt to mimic the situation at the site of skin penetration cercariae have been mechanically transformed in vitro into schistosomula and immediately exposed to human TNF-α . Exposure of these early schistosomula to the human hormone caused a large-scale change in the expression of parasite genes. Exposure of adult worms to human TNF-α caused gene expression changes as well, although the set of parasite altered genes was entirely different from that of schistosomula. This work increases the number of known signaling pathways of the parasite, and opens new perspectives into understanding the molecular components of TNF-α response as well as possibly interfering with parasite-host interaction.