IN-VITRO CULTIVATION OF ANAPLASMA-MARGINALE IN BOVINE ERYTHROCYTES COCULTURED WITH ENDOTHELIAL-CELLS

Primary cultures of Anaplasma marginale infected erythrocytes were use d to determine conditions for in vitro cultivation of the rickettsia. The infected erythrocytes that were maintained by regular addition of Glasgow's MEM with fetal calf serum and uninfected erythrocytes showed a 1-5% increase in percent infected erythrocytes on the evaluation of Giemsa stained smears. This increase in parasitemia resulted in up to 70% change in the number of infected erythrocytes. Go-culture of the infected erythrocytes with endothelial cell monolayers allowed for lon ger maintenance with the parasitemia ranging from 5-13% through four p assages over 16 weeks. Examination of cultures using transmission elec tron microscopy showed initial bodies within the erythrocytes at 10 da ys after the initial passage of the primary culture. The endothelial c ell monolayers in the co-cultures contained multiple initial bodies. W e have demonstrated that A. marginale can be grown for a Limited numbe r of passages in the co-culture system, which will facilitate the deve lopment of a continuous culture of the organism. (C) 1997 Elsevier Sci ence B.V.