Humoral immune response to infection with Encephalitozoon cuniculi in rabbits.

Parenteral administration of Encephalitozoon cuniculi induced an antibody response within 7--11 days. Peroral administration was less effective since only 2 of 6 animals showed seroconversion; they became seropositive within 14--21 days. Sera from animals which became seropositive had high antibody titres during the whole test period. Immune sera from 3 animals were fractionated by gel filtration. With the india-ink immunoreaction test, antibodies to E. cuniculi were found only in the 7S fractions, while the indirect fluorescent-antibody test detected them in fractions 19S and 7S. The 7S fractions were identified as IgG and the 19S fractions as IgM. A program for eradication of encephalitozoonosis, based on these results, is discussed.