Caprine arthritis encephalitis: an example of risk assessment for embryo trading.

The risk of transmission of caprine arthritis encephalitis virus (CAEV) during embryo transfer has been demonstrated in vivo through the detection of CAEV proviral DNA in: (1) flushing media for embryo collection; (2) cells of the cumulus oophorus surrounding the oocytes, ovarian follicle, oviduct and uterine tissues; and (3) testis, epididymis, vas deferens and vesicular glands. Experimentally infected embryos without a zona pellucida (ZP), washed 10 times with Minimum Essential Media (MEM) and 5% Fetal Calf Serum (FCS) solution, were capable of transmitting CAEV. In vitro we demonstrated that granulosa, oviductal, epididymal and embryo cells are fully susceptible to CAEV infection and allow active replication.