Description
Besnoitia besnoiti was in vitro isolated during the first recorded outbreak of bovine
besnoitiosis in Germany. Molecular characterization of the new isolate, named Bb-GER1,
revealed almost 100% identity with other B. besnoiti isolates obtained in Portugal, Spain,
Israel or South Africa, when partial sequences of the 18S ribosomal RNA gene, of the
internal transcribed spacer 1 and of the 5.8S RNA gene were compared. Cystozoites
obtained from skin tissue of one bull were infectious for g-interferon knockout (GKO) mice
by intraperitoneal (ip) inoculation. Tachyzoites were detected in the peritoneal cavity,
spleen, liver and lung of the mice 5 days post-infection. The parasite could be maintained
in GKO mice by ip inoculation for at least 5 passages. Peritoneal washings containing
tachyzoites were obtained from infected mice and used to infect five cell lines (Vero,
MARC-145, NA42/13, BHK21, KH-R). The best growth of tachyzoites was observed in BHK21
cells, but replication occurred to a smaller extent also in MARC-145, NA42/13 and KH-R
cells. Subsequent comparative analyses revealed that after direct infection of these cell
lines with cystozoites derived from bovine skin, the growth was best in NA42/13 cells.
Considerable replication was also observed in the BHK21 and KH-R cell lines. Our
observations on the growth characteristics of Bb-GER1 partially contrast those for other
isolates. The preferential growth in particular cell linesmay be characteristic for particular
B. besnoiti isolates. A potential association between growth properties and differences in
virulence remains to be established. This is the first in vitro isolation of B. besnoiti from
cattle in Germany.
; Basso, W. 
