VACCINATION OF PATAS MONKEYS EXPERIMENTALLY INFECTED WITH SCHISTOSOMA-HAEMATOBIUM USING A RECOMBINANT GLUTATHIONE-S-TRANSFERASE CLONED FROMSCHISTOSOMA-MANSONI

The capacity of a recombinant glutathione S-transferase from Schistoso ma mansoni (rSm28GST) to vaccinate primates (Erythrocebus patas) again st a heterologous infection with Schistosoma haematobium has been test ed Two injections of the purified molecule with Muramyl-Di-Peptide (MD P) as adjuvant resulted in a high level antibody response in the five immunized animals and in a significant reduction in worm fecundity com pared to the controls which received adjuvant alone. Mean levels of da ily egg excretion in urine and faeces were reduced by respectively 55% and 74% although perfusion revealed that worm burdens were similar in both groups. The protective effect was long lasting since it was main tained up to the end of the experiment, 42 weeks after infection. Hatc hing rates and the numbers of intra-uterine eggs were also significant ly affected by the vaccination. Tissue eggs were also drastically dimi nished in the urogenital system (-80%) but the reduction was not stati stically significant. One animal was not protected by the immunization . There was a good correlation between parasitological data and the in tensify of bladder lesions assessed by microscopic examination. Polypo id formations together with an intense exudation of the lamina propria were frequently seen in the controls but rarely in the vaccinated gro up where formation of scar tissue was predominant. These results under line the vaccine potential of the recombinant Sm28GST as a possible va luable prophylactic tool for the control of egg-induced pathology and transmission of African schistosomes.