Susceptibility of porcine preimplantation embryos to viruses associated with reproductive failure.

In the modern biological area, the applications of pig as a laboratory model have extensive prospects, such as gene transfer, IVF, SCNT, and xenotransplantation. However, the risk of pathogen transmission by porcine embryos is always a topic to be investigated, especially the viruses related to reproductive failure, for instance, pseudorabies virus, porcine reproductive and respiratory syndrome virus, porcine parvovirus, and porcine circovirus type 2. It should be mentioned that the zona pellucida (ZP) of porcine embryos can be a barrier against the viruses, but certain pathogens may stick to or even pass through the ZP. With intact, free, and damaged ZP, porcine preimplantation embryos are susceptible to these viruses in varying degrees, which may be associated with the virus-specific receptor on embryonic cell membrane. These topics are discussed in the present review.