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Immune response of sheep (ovis aries) to two venezuelan trypanosoma vivax isolates

Abstract:

Bovine trypanosomosis caused by Trypanosoma vivax, has a significant negative impact on livestock. Due to the limited information on the immune response against this parasite in ruminants, the present investigation was undertaken with the aim to evaluate and compare the immune response of sheep experimentally infected with two T. vivax isolates. The isolates were obtained from different geographic areas of Venezuela (TvLIEM176 from Trujillo State and TvMT1 from Monagas State). Three sheep were inoculated with each isolate and three others were used as controls for a total of nine animals. Every three days (d), during a period of 60 d, blood and serum samples were taken to determine anti-Trypanosoma spp. antibodies (by iELISA), parasitemia, white blood cell count and a leukocyte profile. TvMT1-inoculated animals showed higher levels of antibodies than TvLIEM176-infected animals, although parasitaemia behaved inversely. The TvLIEM176 isolate produced higher levels of parasitemia than the TvMT1 isolate. In addition, lymphopenia was observed in TvLIEM176-infected sheep from day 12 to 36 postinfection, while lymphopenia was not shown in TvMT1-infected animals. It was demonstrated that the humoral immune response against both T. vivax isolates in sheep was different, which may be related to immunosuppression caused by TvLIEM176 isolate due to production of lymphopenia.