Biosafety in embryos and semen cryopreservation, storage, management and transport.

This chapter summarizes pertinent procedures, data and opinions on the potential hazards of disease transmission through liquid nitrogen (LN)-cryopreserved and banked germplasm and tissues for somatic cell nuclear transfer (SCNT) The importance of applying internationally adopted sanitary washing procedures to germplasm as a crucial step towards their successful microbial-free cryopreservation and storage is emphasised. Special attention is given to the survival of pathogens in LN, variety of vitrification methods, sterility of LN, risks associated with the use of straws and cryovials, and LN Dewars including dry shippers. It was experimentally demonstrated that cross-contamination between LN and embryos may occur, when infectious agents are present in LN and if embryos are not protected by use of a sealed container. It is important, therefore, to prevent direct contact of germplasm and reproductive tissues with LN during cryopreservation and their storage as a mandatory measure for reducing the risk of contamination. This includes the usage of hermetically sealed high quality shatter proof freezing containers and/or the application of a secondary enclosure such as "double bagging or straw in straw". A periodic disinfection of cryo-Dewars should be considered as an additional precaution to diminish the potential for inadvertent cross-contamination. It would be advisable to use separate LN Dewars to quarantine embryos derived from infected donors of valuable genotypes or from unknown health status, extinction-threatened species.