Molecular Characterization of the Gene Encoding SJCHGC 03921 Protein of the Lung Stage of Schistosoma Mansoni (7-Days Schistosomula)

The parasitic helminth Schistosoma mansoni (S. mansoni) is a major public health
concern in many developing countries. Over 200 million people have, and another
600 million are at risk of contracting schistosomiasis which is one of the major
neglected tropical diseases. For this dangerous disease the development of long -
lasting immunity through vaccination may be the real solution to control the spread
of the disease. The molecules on the surface or associated with the tegument of S.
mansoni are a major focus as potential vaccine candidates. In the present study, all
surface and internal proteins of the lung stage of the parasite were screened to
increase the chances for the discovery of a unique protein of the parasite to be
targeted by the immune system of the host. Pooled sera were collected from S.
mansoni chronically infected patients, then, purified over a column made of soluble
extract of the lung stage (7-days schistosomula) of S. mansoni. The eluted antibodies
were used to immunoscreen λgt11 cDNA library of 7-days schistosomula. A number
of cDNA clones were identified after three rounds of immunoscreening and plaques
purification. The phage DNAs of the isolated clones were amplified by polymerase
chain reaction (PCR) using λgt11 forward and reverse primers, then, cloned in
PCRTMII plasmid vector. The isolated clone 4-65 was fully sequenced and was found
encoding the gene of SJCHGC 03921 protein of 7-days schistosomula of S. mansoni.
Also, the 0.9 kb cDNA clone was found to have a single open reading frame (ORF)
encoding 269 amino acids, which exhibited 94% homology with the gene of SJCHGC
03921 protein of Schistosoma japonicum.