el Ridi, R., A. Mahrous, A. Afifi, M. Montash, J. Velek, and J. Jezek,
"Human and murine humoral immune recognition of multiple peptides from Schistosoma mansoni glyceraldehyde 3-P dehydrogenase is associated with resistance to Schistosomiasis",
Scandinavian journal of immunology, vol. 54, issue 5, England, pp. 477 - 485, 2001/11/.
AbstractSchistosoma mansoni glyceraldehyde 3-phosphate dehydrogenase (SG3PDH) is a target of cellular and humoral immune responses of Brazilian and Egyptian subjects putatively resistant to reinfection with S. mansoni. In an aim to develop a safe, stable and effective vaccine based on this promising molecule, six peptides derived from its primary sequence were selected based on the lowest homology to human G3PDH. The synthetic peptides were tested by ELISA against plasma of humans putatively susceptible or resistant to reinfection with S. mansoni or S. haematobium following chemotherapeutic cure of previous infection. Repeat experiments indicated that the six peptides bear human B-cell epitopes that bind immunoglobulin (Ig)M, IgG1 and IgG3 antibodies. Resistance to reinfection appeared to be significantly associated with humoral immune responses to multiple peptides. This contention was supported by studies in the murine model, whereby we examined the B cell immune responses of Swiss and inbred BALB/c and C57BL/6 mice immunized with recombinant SG3PDH (rSG3PDH) to the six SG3PDH-derived peptides. The serum antibodies of rSG3PDH-immunized Swiss mice were directed to only one of the six peptides tested by ELISA. Antibodies from rSG3PDH-immunized C57BL/6 and BALB/c mice bound, respectively, to four and six out of six peptides. In contrast to Swiss mice, immunization of C57BL/6 and BALB/c mice with rSG3PDH induced protection against challenge cercariae which reached the level of significance (P < 0.05) for BALB/c mice. The data together indicate that host recognition of multiple peptides of a candidate vaccine antigen is necessary for the expression of its ability to contribute to protective immunity against Schistosomiasis.
el Ridi, R., C. B. Shoemaker, F. Farouk, N. H. El Sherif, and A. Afifi,
"Human T- and B-cell responses to Schistosoma mansoni recombinant glyceraldehyde 3-phosphate dehydrogenase correlate with resistance to reinfection with S. mansoni or Schistosoma haematobium after chemotherapy",
Infection and immunity, vol. 69, issue 1: American Society for Microbiology, pp. 237 - 244, 2001/01/.
AbstractRecently we reported that human T- and B-cell recognition of a 42-kDa protein (p42) in soluble extracts of adult Schistosoma mansoni worms correlates with resistance to reinfection with S. mansoni or S. haematobium. Amino acid microsequencing of p42 revealed that it consists predominantly of schistosome glyceraldehyde 3-phosphate dehydrogenase (SG3PDH). We have expressed SG3PDH in Escherichia coli and purified the recombinant protein in a soluble and enzymatically active form. Recombinant SG3PDH (rSG3PDH) reacted with human monospecific antibodies to p42. Lymphoproliferation and production of interleukin-4 and gamma interferon (IFN-gamma) after in vitro stimulation with rSG3PDH and serum isotype responses to rSG3PDH were examined in individuals with extremes of resistance and susceptibility to reinfection after treatment of previous S. mansoni or S. haematobium infection. Lymphoproliferation and IFN-gamma production in response to rSG3PDH and the presence of serum immunoglobulin G1 (IgG1), IgG3, and IgA antibodies to rSG3PDH generally characterized individuals who are resistant to reinfection after chemotherapy. The data indicate that T- and B-cell immune reactivity to rSG3PDH correlates with resistance to reinfection, confirming previous studies identifying SG3PDH as a target of protective immunity in humans, and suggest that SG3PDH should be investigated as a possible vaccine for human schistosomiasis.
el Ridi, R., S. Ragab, S. Lewis, and A. Afifi,
"Role of IgE in primary murine Schistosomiasis mansoni",
Scandinavian journal of immunology, vol. 53, issue 1, England, pp. 24 - 31, 2001/01/.
AbstractSchistosoma mansoni infection proceeds in normal mice in the absence of detectable levels of polyclonal or specific immunoglobulin (Ig)E until worms mature and deposit eggs. Hence, the course of a primary S. mansoni infection is not expected to vary appreciably in mice with defects in the IgE production. Experimental increase of IgE production early after infection may, however, influence worm development. In the first approach towards this goal, BALB/c mice were injected with interleukin(IL)4 to raise the level of endogenously synthesized IgE. A significant increase in serum polyclonal IgE and antischistosome IgG1 during the prepatent period was not associated with significant changes in worm and egg burden or liver pathology. During the second approach, mice were injected with IgE which was affinity purified from serum of BALB/c mice infected for 16 weeks with S. mansoni. The purified IgE bound to carbohydrate-independent epitopes of soluble antigens from 3 h larvae, adult worms and eggs and recognized the schistosomular surface membrane. No differences in worm and egg load or granuloma number and size were noted between untreated and exogenous IgE-injected mice. Together, the data demonstrate that by itself IgE does not influence the outcome of infection in primary murine S. mansoni.