To study the effects of ibaraki virus on preimplantation mouse embryos collected from prepubertal ICR and BALB/cByJ mice (30^-40days old) by superovulation, zona pellucidaintact(ZPI) or free(ZPF) embryos(n=7i4) of 4- to E cell and morulae were exposed to 105.8 TCIDso of the virus up to 96 hours. The embryos were examined morphologically by observing the degeneration and hatching rates, and virologica:ay and immunologically by determining the presence of infection with the virus, in addition, the
effect of washing the embryos to remove virus possibly attached to was also investigated.
The ZPI 4- to 8-cell embryos and morulae exposed to the virus showed considerably higher degeneration rate than those not exposed, for 96, and for 72 to 96 hours, respectively(p[0.01).
The ZPF 4- to 8-cell embryos and morulae exposed to the virus showed considerably higher degeneration rates than those not exposed, throughout the whole culture hours in vitro (p[9.01).
The ZPI 4- to 8-cell embryos and morulae not exposed to the virus showed considerably higher rates of hatched blastocyst than those exposed (p<0.01).
The virus infection rates of the ZPF 4- to 8-cell embryos and morulae were significantly higher than those of the ZPI embryos according to cell culture system.
The viral antigen was detected exclusively on the zona pellucida of ZPI embryos, while the antigen was evenly distributed in the blastomeres of ZPF embryos by the immunofluorescent assay.
In the ZPI embryos exposed to ibaraki virus, the virus was detected in the two timeswashing groups, but not in the ten times-washing groups.
The results indicated that zona pellucida of marine embryos would provide an effective protection and that ten times-washing of the ZPI embryos previously exposed to the virus was effective to remove virus from the embryos.
|