The effect of high concentrations of cryoprotectants on the passage of bovine viral diarrhea virus through the zona pellucida of in vitro fertilized embryos
A. Bielanski et al., The effect of high concentrations of cryoprotectants on the passage of bovine viral diarrhea virus through the zona pellucida of in vitro fertilized embryos, ANIM REPROD, 55(2), 1999, pp. 83-90
The effect of high concentrations of cryoprotectants on the passage of bovi
ne viral diarrhea virus (BVDV) through the zona pellucida (ZP) of intact bo
vine embryos during the pre-freezing step of cryopreservation was investiga
ted in a series of experiments. In vitro fertilized (IVF) embryos at the bl
astocyst stage were exposed to 10(6) TCID50 BVDV (non-cytopathic NY-1 strai
n) in a 30% suspension of either ethylene glycol, glycerol, DMSO, or 2 M su
crose in physiological saline for 10 min at 20 degrees C. Subsequently, the
embryos were washed free of residual unbound viral particles, and the ZP o
f some embryos were removed by micromanipulation. Groups of ZP-intact embry
os, ZP-free embryonic cells and their respective ZP were then tested separa
tely for the presence of virus. The infectious virus was detected in associ
ation with 81% (17/21) of samples containing non-micromanipulated ZP-intact
embryos which were exposed to the virus and cryoprotectants and then washe
d 10 times and in 83% (43/53) of the samples containing only ZP from microm
anipulated embryos (P > 0.05). The virus was not found in the samples conta
ining the corresponding embryonic cells of embryos exposed previously to th
e virus and cryoprotectants. It was concluded that the transfer of embryos
from the isotonic PBS solution into a highly hypertonic cryoprotectant solu
tion did not cause the passage of BVDV through ZP and its entry to embryoni
c cells. (C) 1999 Elsevier Science B.V. All rights reserved.