Amelioration of virulent Babesia bovis infection in calves by administration of the nitric oxide synthase inhibitor aminoguanidine

Calves undergoing initial infection with a virulent strain of the haemoprot ozoan parasite Babesia bovis were treated with aminoguanidine (AG), an inhi bitor of the inducible form of nitric oxide synthase (iNOS). The mean maxim um parasitaemia of the AG treated calves was significantly lower than that of the control cattle. In addition, the febrile response and decrease in pa cked cell volume (PCV) observed during acute infection were significantly a meliorated in the AG treated cattle relative to the controls. However, AG h ad no effect on the multiplication of B. bovis in the microaerophilous stat ionary-phase (MASP) in-vitro culture system, These results provide evidence of a role for nitric oxide (NO) produced in response to acute infection in the pathology of bovine babesiosis.