ULTRASTRUCTURE OF ANAPLASMA-MARGINALE THEILER IN DERMACENTOR-ANDERSONI STILES AND DERMACENTOR-VARIABILIS (SAY)

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (12) , 1966-1976
Abstract
Cattle were inoculated with a Virginia isolate of A. marginale Theiler and served as an infective source for laboratory-reared D. andersoni Stiles and D. variabilis (Say) nymphs. A. marginale was demonstrated by EM in gut tissues of replete nymphal ticks and in unfed, incubated and feeding adult ticks exposed to the organism as nymphs when they fed on an infected cow. The A. marginale organisms in replete nymphs and adult feeding ticks were morphologically similar to A. marginale described previously from infected bovine erythrocytes. Colonies of A. marginale were demonstrated by light microscopy and EM in midgut epithelial cells of unfed adult D. andersoni and D. variabilis that had been incubated at 37.degree. C for 3 days. A. marginale in colonies were very pleomorphic. Small electron-dense particles were demonstrated in all infected tick stages studied, but were most evident in colonies from incubated, unfed ticks. They may represent a reproductive form of A. marginale.