Preliminary development of a live drug-controlled vaccine against bovine babesiosis using the Mongolian gerbil, Meriones unguiculatus.

This study investigated the practicality and potential of the gerbil, Meriones unguiculatus, as a source of live Babesia divergens vaccine and also as a model for the use of the vaccine in cattle. A series of experiments with gerbils concerning vaccine infectivity, immunogenicity and safety were carried out. It was concluded that the use of RPMI medium/40% foetal calf serum as a diluent improved vaccine infectivity, but that the parasitaemia of the blood obtained from donor gerbils had little or no effect. The immunostimulants levamisole and killed Corynebacterium parvum improved vaccine immunogenicity and it was also shown that the subcutaneous route of infection resulted in the greatest host response. Control of vaccine virulence with drugs was only possible when drugs with prophylactic properties, such as imidocarb and long-acting oxytetracycline, were used. More studies are required on all these topics, particularly with regard to their applicability to cattle, and also concerning the possible attenuation of the parasite by manipulation in the gerbil host.