Treatment of urinary schistosomiasis by chemotherapy remains challenging due to rapid re-infection and possibly to limited susceptibility to praziquantel treatment.
Therefore, therapeutic vaccines represent an attractive alternative control strategy. The objectives of this study were to assess the safety and tolerability profile of the recombinant 28 kDa glutathione S -transferase of Schistosoma haematobium rSh28GST in healthy volunteers, and to determine its immunogenicity. A six-month follow-up was performed with both clinical and biological evaluations.
Immunogenicity of the vaccine candidate was evaluated in terms of specific antibody production, the capacity of sera to inhibit enzymatic activity of the antigen, and in vitro cytokine production. Among the 24 healthy male participants no serious adverse events were reported in the days or weeks after administration. No hematological nor biochemical evidence of toxicity was detected. Immunological analysis showed that rSh28GST was immunogenic. The induced Th2-type response was characterized by antibodies capable of inhibiting the enzymatic activity of rSh28GST.
Together with previous preclinical results, the data of safety, tolerability and quality of the specific immune response provide evidence that clinical trials with rSh28GST could be continued in humans as a potential vaccine candidate against urinary schistosomiasis. Therapeutic vaccines represent an attractive tool in the fight against schistosomiasis. Pre-clinical immunization studies with the schistosome enzyme 28 kDa glutathione S -transferase 28GST has been shown to significantly reduce schistosome egg production and subsequent pathology.
The objective of this study was to assess the safety and immunogenicity of the recombinant 28GST of Schistosoma haematobium rSh28GST in healthy adult volunteers. Some mild adverse events were noted, including minor reactions at the injection site reported for four subjects receiving rSh28GST, but there was no hematological or biochemical evidence of toxicity. Immunological analysis showed that rSh28GST induced a consistent immune response characterized by antibodies endowed with the capacity to inhibit 28GST enzymatic activity.
