Effects of inoculum route and dose on the immune response of common carp, Cyprinus carpio to the blood parasite, Trypanoplasma borreli.

Carp were inoculated intramuscularly (im) or intraperitoneally (ip) with different doses of live Trypanoplasma borreli. Prepatent period was shortened by using the im route and by increasing the dose. Haematocrit was reduced following im inoculation with 9.5 x 10(5) parasites. Most fish recovered between 8 and 13 weeks post-inoculation (wpi). Neither parasitaemia nor anaemia was detected in any recovered fish following homologous challenge. An enzyme-linked immunosorbent assay was developed to quantitate antibody response elicited by the parasite. Antibody levels rose rapidly during the first 4 wpi. The response elicited by increased dose was significantly higher only at 4 wpi. Route of exposure did not affect antibody response. Peak responses coincided with decline and eventual absence of parasitaemia.