Abstract
BackgroundSchistosomiasis remains an important global public health problem, as millions of people are at risk of acquiring infection. An ideal method for sustainable control of schistosomiasis would be to develop an efficient vaccine. Schistosomes can survive in the host vascular system by immune evasion, regulating the host complement cascade. Schistosoma japonicum tetraspanning orphan receptor (SjTOR) is a complement regulator, which is a tegument membrane protein. To date there is no experimental evidence to explain the function of SjTOR.ResultsWe cloned the first extracellular domain of the SjTOR (SjTOR-ed1) gene and expressed the gene in Escherichia coli. The expression level of SjTOR in different developmental stages of S. japonicum was assessed by quantitative real-time RT-PCR. Western blotting showed that recombinant SjTOR-ed1 (rSjTOR-ed1) could be recognised by schistosome-infected mouse serum. Immunolocalization indicated that the protein was mainly distributed on the tegument of the parasite. Haemolytic assays and ELISA revealed that rSjTOR-ed1 could inhibit complement hemolysis and bind to complement C2. Purified rSjTOR-ed1 emulsified with ISA206 adjuvant could induce a significant reduction of worm burden from 24.51 to 26.51%, and liver egg numbers from 32.92 to 39.62% in two independent trials in mice.ConclusionsThe results of this study indicated that rSjTOR-ed1 could inhibit complement hemolysis and bind to complement C2, and it is a potential vaccine candidate that protects against S. japonicum infection.
Highlights
Schistosomiasis remains an important global public health problem, as millions of people are at risk of acquiring infection
A comparison of amino acid sequences showed that Schistosoma japonicum tetraspanning orphan receptor (SjTOR) was 77.0, 72.0, and 75.0% identical to orthologs from S. mansoni, S. haematobium, and T. cruzi, respectively
The sequence of this domain of SjTOR shares a high level of sequence identity with other Tetraspanning orphan receptor (TOR), there are four amino acid differences compared with the TORs of other Schistosoma species (Fig. 1)
Summary
Schistosomiasis remains an important global public health problem, as millions of people are at risk of acquiring infection. Schistosomes can survive in the host vascular system by immune evasion, regulating the host complement cascade. Schistosomiasis is a neglected tropical disease in humans, and it remains a serious global public health problem that affects over 200 million people in 74 developing countries and causes hundreds of thousands of deaths annually [1, 2]. Ma et al Parasites & Vectors (2017) 10:288 schistosomiasis is difficult to control To control this disease, there is an urgent need to develop alternative therapies and effective vaccines [8] that could reduce the release of eggs and restrict parasite transmission or induce which kind of activity against schistosome infection. Schistosomal proteins on the surface of the tegument and some regulatory proteins that impede the complement cascade might represent ideal molecules for the discovery of vaccine candidates [9, 12,13,14]
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