Abstract
BackgroundSchistosomiasis continues to be one of the most prevalent parasitic diseases in the world. Despite the existence of a highly effective antischistosome drug, the disease is spreading into new areas, and national control programs do not arrive to complete their tasks particularly in low endemic areas. The availability of a vaccine could represent an additional component to chemotherapy. Experimental vaccination studies are however necessary to identify parasite molecules that would serve as vaccine candidates. In the present work, C57BL/6 female mice were subcutaneously immunized with an n-butanol extract of the adult worm particulate membranous fraction (AWBE) and its protective effect against a S. mansoni challenge infection was evaluated.Methodology and FindingsWater-saturated n-butanol release into the aqueous phase a set of membrane-associated (glyco)proteins that are variably recognized by antibodies in schistosome-infected patients; among the previously identified AWBE antigens there is Alkaline Phosphatase (SmAP) which has been associated with resistance to the infection in mice. As compared to control, a significantly lower number of perfuse parasites was obtained in the immunized/challenged mouse group (P<0.05, t test); and consequently, a lower number of eggs and granulomas (with reduced sizes), overall decreasing pathology. Immunized mice produced high levels of sera anti-AWBE IgG recognizing antigens of ∼190-, 130-, 98-, 47-, 28-23, 14-, and 9-kDa. The ∼130-kDa band (the AP dimer) exhibited in situ SmAP activity after addition of AP substrate and the activity was not apparently inhibited by host antibodies. A preliminary proteomic analysis of the 25-, 27-, and 28-kDa bands in the immunodominant 28–23 kDa region suggested that they are composed of actin.ConclusionsImmunization with AWBE induced the production of specific antibodies to various adult worm membrane molecules (including AP) and a partial (43%) protection against a challenging S. mansoni infection by mechanism(s) that still has to be elucidated.
Highlights
Schistosomiasis is still one of the most prevalent and serious parasitic diseases worldwide; over 200 million persons are currently infected in endemic areas, over 85% of which live in sub-Sahara Africa [1,2]
Immunization with adult worm n-butanol extract (AWBE) induced the production of specific antibodies to various adult worm membrane molecules and a partial (43%) protection against a challenging S. mansoni infection by mechanism(s) that still has to be elucidated
The results showed that immunization with AWBE induced a strong humoral response (IgG) with 43% protection against a challenge infection
Summary
Schistosomiasis is still one of the most prevalent and serious parasitic diseases worldwide; over 200 million persons are currently infected in endemic areas, over 85% of which live in sub-Sahara Africa [1,2]. Schistosomes strain resistance to PZQ has been shown in the laboratory in as few as six generations [6]. In this context, the advent of a schistosomiasis vaccine would be a significant addition to current methods of control of this disease, because in the case of schistosomiasis, a sterilizing vaccine is not essential and partial reduction in worm burdens could reduce morbidity, pathology and limit parasite transmission [7]. C57BL/6 female mice were subcutaneously immunized with an n-butanol extract of the adult worm particulate membranous fraction (AWBE) and its protective effect against a S. mansoni challenge infection was evaluated
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