Anaplasma marginale PURE ISOLATE OBTAINED IN COLOSTRUM-DEPRIVED NEWBORN CALVES

Abstract

This study was conducted with the objective of obtaining pure autochthonous isolates of Anaplasma marginale from blood samples of bovines that have been raised in the tick-borne disease endemic area of the municipality of Goiânia. The inoculum of A. marginale was prepared from a donor animal, known to be natural carrier of hemoparasite mixed infections, after treatment with a babesicid sterilizing dose of imidocarb dipropionate. A 20 mL blood sample was collected from the donor animal 2 days post-infection and then transferred to a colostrum-deprived and hemoparasite free newborn calf. The receptor animal showed signs of fever and apathy with patent A. marginale parasitemia 30 days after inoculation. Blood sample was then collected and prepared as stabilates to be cryopreserved and to take part of an autochthonous blood parasites isolates library. The isolate purity was assured concomitantly by specific seroconversion tests, by PCR and by finally by the subinoculation of susceptible calves with the cryopreseved stabilates. It was confirmed that the use of colostrum-deprived free newborn calves as susceptible animals may be considered a practical and effective model to obtain pure hemoparasite isolates in endemic areas with additional advantages such as feasibility and low cost.

Key words: Anaplasma marginale, isolates, calves, bovine anaplasmosis.