HUMORAL IMMUNE RESPONSE OF SHEEPS EXPERIMENTALY INFECTED WITH TRYPANOSOMA EVANSI.

P. B. Passos, L. C MARQUES, R. Z. MACHADO, F. A. CADIOLI, L. P. C. T. AQUINO, T. H. C. PATELLI, T. R. ALMEIDA, M. C. A. TEIXEIRA

Abstract


This research investigated the humoral immune response in sheep experimentally infected with Trypanosoma evansi. Ten healthy eight-months-old crossbred ewes were used. The animals were previously tested by fluorescent antibody test (IFAT) and were serum negative for T. evansi. Four of them were kept as non-infected controls; three animals were experimentally infected by intravenous route with approximately 2.4 x 106 and the remaining three with 2.4 x 107 trypomastigotes of T. evansi. Serum samples of the experimentally T. evansi-infected and non-infected sheeps were obtained before inoculation and daily thereafter until 14 days post infection (DPI). Later, the serum samples were obtained weekly and biweekly until the 133rd and 253rd DPI, respectively. No clinical signs were observed. The immune responses started on the 14th DPI and progressive increases in antibodies levels were documented between the 30th and the 90th DPI. After this period the levels of antibodies remained high up to the end of the observation period. Sheeps experimentally infected with 2.4 x 107 trypomastigotes of T. evansi showed the highest IFAT values.
KEY-WORDS: Trypanosoma evansi. Trypanosomiasis. Sheep. Immune response



DOI: http://dx.doi.org/10.15361/2175-0106.2006v22n2p159-164