Pythium insidiosum is a zoosporic fungi living in flooded areas which can infect humans and animals. Natural infection in these species results in clinical pythiosis, a granulomatous disease of difficult treatment. Immunotherapy with antigens obtained from cultures of the agent is a promising alternative therapy. In order to evaluate the effect of adjuvants in the immunologic response to P. insidiosum antigens, 24 rabbits were assigned to four groups and immunized with mycelian mass antigen with each of there adjuvants. Group I: aluminum hydroxide; group II: Freund’s adjuvant; group III: mineral oil and group IV: distilled water-control. The effects of the adjavants were evaluated by measuring the levels of anti-pythium imunoglobulin G (IgG) produced by the immunized rabbits at different time-points after immunization, using an ELISA test. During phase 1, the animals were immunized three times (days zero, 14 and 28) and serologically tested at days 14, 21, 28 and 35. The oil adjuvants (groups II and III) were statistically superior to groups I and IV. During phase 2 (from day 42 to 120) each group was subdivided in two, with one subgroup having additional immunizations at days 42, 56, 68 and 82 and the other having the treatment interrupted. Among the rabbits with continued immunizations, groups I, II and III (adjuvants) had statistically higher IgG levels than GIV. Among rabbits with interrupted treatment, GI, GII and presented stable IgG levels and were statistically superior to the control group, that presented decrease in the levels. These results demonstrated that the adjuvants were capable of inducing stronger and longer imunologic responses (IgG) to P. insidiosum antigens. Therefore, the use of adjuvants associated with P. insidiosum antigens may increase the recovery rates obtained through immunotherapy.
Pythium insidiosum; immunotherapy; adjuvants; rabbits
