REPLICATION OF CYTOPATHIC AND NONCYTOPATHIC BOVINE VIRAL DIARRHEA VIRUS IN ZONA-FREE AND ZONA-INTACT IN VITRO-PRODUCED BOVINE EMBRYOS AND THE EFFECT ON EMBRYO QUALITY
G. Vanroose et al., REPLICATION OF CYTOPATHIC AND NONCYTOPATHIC BOVINE VIRAL DIARRHEA VIRUS IN ZONA-FREE AND ZONA-INTACT IN VITRO-PRODUCED BOVINE EMBRYOS AND THE EFFECT ON EMBRYO QUALITY, Biology of reproduction, 58(3), 1998, pp. 857-866
The aim of the present study was to determine whether or not cytopathi
c (CP) and noncytopathic (NCP) bovine viral diarrhea virus (BVDV) are
able to replicate within in vitro-produced embryos and to investigate
whether inoculation of embryos with BVDV affects their normal developm
ent. Zona pellucida (ZP)-free oocytes, zygotes, 8-cell-stage embryos,
morulae, and hatched blastocysts (HE) were incubated for 1 h in 1 mi o
f Minimal Essential Medium containing 10(6.00) tissue culture infectio
us dose (TCID)(50)/ml NCP BVDV isolate 22146 or 10(6.25) TCID50/ml CP
BVDV strain Oregon C24V. At 0, 12, 24, 36, 48, 60, and 72 h postinocul
ation (hpi), groups of embryos were collected for virus titration. A s
mall amount of newly produced virus was detected in 8-cell embryos at
60 hpi (10(1.8) TCID50/100 cells), but only for CP BVDV. For ZP-free m
orulae and HE, maximal intracellular virus titers were, respectively,
10(1.47) and 10(2.33) TCID50/100 cells at 48 hpi for the CP biotype an
d 10(0.64) and 10(0.84) TCID50/100 cells at 72 hpi for the NCP biotype
. Only an infection with CP BVDV had a significant inhibitory effect o
n further development of ZP-free morulae. It can be concluded that ZP-
free in vitro-produced embryos are permissive to an infection with BVD
V, with increasing susceptibility of the embryos in accordance with th
eir developmental stage. In contrast to observations in ZP-free in vit
ro-produced embryos, no virus replication or signs of embryonic degene
ration were detected in ZP-intact in vitro-derived embryos.