الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Schistosomiasis is a neglected tropical disease responsible for significant morbidity and mortality. Globally, WHO in 2019, reported that schistosomiasis infects about 236 million people and is endemic in 51 countries. The latest study carried out in Egypt reported that S. mansoni is mainly prevalent in lower Egypt (17.5% to 42.9 %) while S. haematobium is mainly prevalent in upper Egypt (4.8% to 13.7%).
Currently, PZQ is the drug of choice for the treatment of schistosomiasis. Although it is effective, cheap, and well-tolerated, PZQ does not act on the immature forms of the parasite, and most importantly its effectiveness is declining due to the development of drug resistance. The latter is the main motivation behind the recent increase in research on schistosomes. Moreover, no effective vaccines are available to confer any form of protection against schistosomiasis.
The primary goal of researchers is to devise novel drugs and vaccines against schistosomiasis. To achieve that, it is imperative to understand schistosomes biology by analysing their genome, transcriptome, and proteome. S. mansoni genome was published in 2009 which further facilitated its transcriptomic profiling. In the process of gene expression, the genome is transcribed into transcriptomes (mRNA) which is in turn translated into proteomes (proteins necessary for the survival of the parasite). In order to identify possible drug or vaccine targets, researchers focused on the genes expressed in the genome using a variety of post-genomic technologies such as microarray, RNA-seq, SAGE, and RT-qPCR. Such analysis will thoroughly clarify the molecular basis of essential biological processes such as nutrition, immune evasion, and energy metabolism.
Our motivation to conduct the current study was based on the desire to investigate the expression of specific genes within the mammalian life cycle stages of the Egyptian strain of S. mansoni. We compared the expression of genes encoding lactate dehydrogenase, metalloprotease, aspartic protease, and tegumental phosphodiesterase SmNPP-5 in different developmental stages of S. mansoni namely cercariae, 7-days old schistosomulae, juvenile worms, 38-days and 48-days old adult males and females. The analysis of gene expression was performed using SYBR green RT-qPCR. Interestingly, to our knowledge, the Egyptian strain was not a candidate for research in the gene expression profiling of the selected genes in the previously reported literature.
The four selected genes in the current study were chosen based on the function of the proteins they encode. Lactate dehydrogenase catalyses the interconversion of lactate to pyruvate in the process of glycolysis essential for providing the parasites with the energy needed to survive. Metalloproteases act as both endo and exopeptidase and hence mediate a variety of physiological processes such as proliferation, migration, and peptide processing. Aspartic protease is a digestive enzyme that catalyses the degradation of human haemoglobin ingested by the schistosomes and hence it is a representative of the internal host-parasite interface. Finally, tegumental phosphodiesterase SmNPP-5 is a representative of the external host-parasite interface and was previously reported as being a potential virulence factor in schistosomes.