INVASION AND REPLICATION OF BRUCELLA-ABORTUS IN 3 DIFFERENT TROPHOBLASTIC CELL-LINES

This study was performed to compare the replication of the pathogenic strain Brucella abortus 2308 in three trophoblastic cell lines derived bovine placentas at different gestational stages. The trophoblastic c ell lines were obtained from a 13-15 day embryo, from 5-month placento mal tissue and from an 8-month extra-placentomal portion of the placen ta. The infection rate was similar in all cell lines at 4 h. Colony-fo rming Units were counted at 4, 8, 12, 24 and 30 h post-inoculation. At 12, 16, 24 and 30 h B. abortus rapidly replicated within the 5-month and 8-month trophoblastic cell lines, but grew slowly within trophobla stic cells derived from embryonic tissue. Electron microscopic studies consistently showed clusters of B. abortus in trophoblastic cells der ived from 5- and 8-month placentas, while few cells of the embryonic l ine were infected and these contained only 1-2 bacteria per cell. It w as concluded that B. abortus can infect trophoblastic cells throughout the gestational period but bacterial multiplication does not occur in these cells before middle or late gestation.