Efficacy of the International Embryo Transfer Society (IETS) washing procedure for rendering oocytes matured in vitro free of bovine viral diarrhea virus (BVDV)

Interaction of bovine viral diarrhea virus with bovine cumulus-oocyte complex during IVM: Detection in permissive cells

Structural changes in the zona pellucida (ZP) of bovine oocytes seem to modulate their interaction with various viral agents, facilitating the viral infection in in vitro production systems. To evaluate the susceptibility of bovine oocytes to noncytopathogenic bovine viral diarrhea virus (ncp-BVDV), cumulus-oocyte complexes were exposed to 10(7) ​tissue culture-infective doses (TCID50)/mL of an ncp-BVDV strain during IVM (in vitro maturation). After that, cumulus cells and the ZP were removed by hyaluronidase and pronase treatment, respectively, and the percentages of oocytes with polar body were analyzed as a sign of nuclear maturation. After passage through cell culture, the virus was isolated from granulosa cells, ZP-free mature oocytes, and ZP-intact mature oocytes. These results were confirmed by reverse transcription-polymerase chain reaction. After consecutive washes, the virus remained associated with ZP-free oocytes, maintaining its replication and infectivity in permissive cells. Based on these findings, it is concluded that the classical viral isolation procedure has a predictive value to detect BVDV associated with ZP-free oocytes and that it was novelty demonstrated that both washing and trypsin treatment of oocytes were ineffective to remove BVDV infection.

Shaping the norms that regulate international commerce of embryos

As various embryo technologies in livestock were developed and evolved to a state of usefulness over the past 40 years, scientists with a specific interest in infectious diseases sought to determine the epidemiologic consequences of movement, especially international movement, of increasing numbers of embryos. Many of the foundational studies in this area were reported in Theriogenology, beginning in the 1970s and especially throughout the 1980s and 1990s. Unquestionably, Theriogenology has been a widely used venue for dissemination of basic information on this subject, which ultimately led to the development of the now universally accepted techniques for certification of embryo health. Today it is well-recognized that movement in commerce of embryos, especially in vivo-derived embryos, is a very low-risk method for exchange of animal germ plasm. This paper chronicles the evolution of strategies for health certification of embryos. An overview is provided of the calculated efforts of practitioners, scientists, and regulators to organize, forge necessary partnerships, stimulate needed research, provide purposeful analysis of the results, and, through these processes, guarantee the universal acceptance of efficient protocols for certifying the health of embryos intended for movement in international commerce.