Experimental reproduction of bovine fetal Neospora infection and death with a bovine Neospora isolate.
Studies were conducted to determine the pathogenic potential of the recently isolated bovine Neospora protozoa (BPA-1) for the bovine fetus. Cows chosen for study had Neospora titers < 160 using an indirect immunofluorescent antibody (IFA) test. Four experimental groups were studied. In group 1, 2 fetuses were inoculated in utero at 118 days gestation with culture-derived Neospora tachyzoites. A pregnant control cow was housed in the same pen, observed daily and screened serologically for evidence of exposure to Neospora. In group 2, 2 cows were infected with Neospora tachyzoites at 138 or 161 days gestation, and 1 control cow was given uninfected cell culture suspension simultaneously at 154 days gestation. Groups 3 (85 days gestation) and 4 (120 days gestation) each consisted of 2 cows infected with Neospora tachyzoites and 1 control cow given uninfected material at the same stage of gestation. Dead fetuses were surgically removed from the infected cows in group 1 on postinfection day (PID) 17. The histopathology was compatible with protozoal fetal infection, and protozoa were identified by immunohistochemistry. Viable fetuses were removed surgically from cows in group 2 on PID 28-30. The histopathology was compatible with protozoal fetal infection, protozoa were identified by immunoperoxidase techniques, and Neospora tachyzoites were reisolated in vitro from tissues of the 2 infected fetuses. In groups 3 and 4, the control fetus and 1 infected fetus were removed surgically between PID 26 and PID 33. The remaining infected cows were observed until fetal death or abortion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)
Barr
B C
BC
California Veterinary Diagnostic Laboratory System, School of Veterinary Medicine, University of California, Davis 95616.
Rowe
J D
JD
Sverlow
K W
KW
BonDurant
R H
RH
Ardans
A A
AA
Oliver
M N
MN
Conrad
P A
PA
D000034:Abortion, Veterinary / Q000469:parasitology; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology* / Q000473:pathology; D003044:Coccidia / Q000302:isolation & purification / Q000472:pathogenicity*; D003048:Coccidiosis / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D005260:Female; D005313:Fetal Death / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D005315:Fetal Diseases / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D011247:Pregnancy