Vaccination with recombinant paramyosin in Montanide ISA206 protects against Schistosoma japonicum infection in water buffalo.

BACKGROUND

Schistosomiasis japonica is a zoonosis and presents significant public health problems in China and the Philippines. Vaccines targeting domestic animals constitute attractive control measures.

METHODS

We conducted three vaccine trials to evaluate the protective efficacy of recombinant full-length paramyosin (rSj97) in water buffalo. Animals were immunized with 3 doses of rSj97 adjuvanted with ISA206 at 250μg/dose or 500μg/dose at 4wk intervals before challenge with 1000 Schistosoma japonicum cercariae. The primary outcome was worm burden assessed by portal perfusion 8-10weeks post challenge. Safety measures included weight, temperature, body condition score, hemogram and routine assays for hepatic and renal function.

RESULTS

The three-dose regimen was well tolerated in all three trials. In the first trial, vaccinated buffalo had 51.5% lower worm burden post challenge compared to controls. In the second trial, buffalo immunized with 500μg/dose of rSj97 had 57.8% lower worm burden compared to controls (p=0.026). A similar but not significant reduction (60.9%) was observed with animals administered with 250ug rSj97/dose. In the third trial, buffalo immunized with a 500μg/dose of rSj97 had 57.8% lower worm burden compared to controls (p=0.014).

CONCLUSIONS

These findings indicated that rSj97 is a safe and promising vaccine candidate for schistosomiasis japonica in water buffalo.