Immunoprophylactic polypeptides for schistosomiasis

DETAILED DESCRIPTION OF THE INVENTION It has been discovered that epitopes which are common to two glycoproteins (38 kDa and 200 kDa) of schistosomula of S.
mansoni are able to provide protection against infection by S.
mansoni.
The epitope (or epitopes) on the 38 kDa protein are exposed to the surface of the schistosomula.
The epitope on the 200 kDa protein is apparently not exposed to the surface of schistosomula.
The 38 kDa protein is immunologically cross-reactive with antisera to both bovine smooth uterine muscle myosin as well as C.
elegans myosin.
However, the particular epitopes of the present invention which are shared by the 200 and 38 kDa proteins and which are exposed to the surface of schistosomula, are not immunologically cross-reactive with the anti-myosin antisera of cows or C.
elegans.
In addition, other previously known antibodies which are cross-reactive with the 38 kDa glycoprotein, such as monoclonal antibody 128 (Dalton, et al.
, Experimental Parasitology, vol.
63, pp.
215-226, 1987) are not immunologically cross-reactive with the epitopes identified by the present invention.
Previously described antibodies which recognize surface epitopes on the 38 kDa glycoprotein are directed against glycanic moieties.
One benefit of the epitopes identified by the present invention (as compared to the previously identified glycanic epitopes) is that the protein epitopes can be synthesized by means of organisms containing recombinant DNA.
The proteinaceous character of the epitopes identified in the present invention is evident from the following fact: the epitopes are identified by antisera which were raised against lysates of bacteria infected with recombinant phage.
As bacteria do not glycosylate proteins, the epitopes must be protein epitopes rather than glycanic epitopes.
A fusion protein according to the present invention may include portions of any bacterial protein which is well expressed.
Particularly convenient fusion proteins are made using portions of the amino terminal end of the enzyme beta-galactosidase