Screening for HIV, hepatitis B and C infection in a population seeking assisted reproduction in an inner London hospital

Evaluation of risks of viral transmission to recipients of bovine embryos arising from fertilisation with virus-infected semen

This scientific review was prompted by recent legislation to curtail the use of semen from potentially virus-infected bulls to produce embryos for import into the European Union. From studies in laboratory animals, humans and horses, it is apparent that viruses may sometimes attach to, or be integrated into, spermatozoa, although in domestic livestock, including cattle, this seems to be a rare phenomenon, and carriage of virus through the zona pellucida into the oocyte by fertilising sperm has never been described in these species. Four specific viruses; enzootic bovine leukosis (EBLV), bovine herpesvirus-1 (BoHV-1), bovine viral diarrhoea virus (BVDV) and bluetongue virus (BTV), all of which tend to cause subclinical infections in cattle, but which can occur in bovine semen, are examined with regard to the risks that use of infected semen might lead to production of infected embryos. With regard to in vivo-derived embryos, when internationally approved embryo processing protocols are used, the risks from EBLV- and BTV-infected semen are negligible, and the same is almost certainly true for semen infected with BoHV-1 if the embryos are also treated with trypsin. For BVDV, there is insufficient data on how the virus is carried in semen and how different BVDV strains can interact with sperm, oocytes and embryos. There is a potential, at least, that in vivo-derived embryos resulting from infected semen might carry BVDV, although field studies so far suggest that this is very unlikely. With regard to in vitro-produced embryos, use of semen infected with any of the four viruses, with the probable exception of EBLV, will often lead to contaminated embryos, and virus removal from these embryos is difficult even when the internationally approved embryo processing protocols are used. However, it has never been demonstrated that such embryos have resulted in transmission of infection to recipients or offspring.

Laboratory safety during assisted reproduction in patients with blood-borne viruses

For couples where one or both partners are infected with human immunodeficiency virus or hepatitis C, the doors to receiving fertility care are opening as a result of better antiviral medication, better long-term prognosis and consequent changes in attitude. In line with this, fertility centres electing to treat couples with blood-borne viral (BBV) infection need to re-examine their policies and procedures to ensure the safety of their staff and both non-infected and infected patients during assisted reproduction treatments. At a time when the European Tissue Directive aims to introduce quality standards for assisted reproduction throughout Europe, we highlight the risks involved when treating patients with known BBV infections and argue that safety cannot be met with any certainty unless samples from such patients are handled within a separate high security laboratory or laboratory area, technically adapted to ensure minimal cross-contamination risk to uninfected gametes and embryos.

Transmission virale et assistance médicale à la procréation : le cas des Herpesviridae

Procreation with sperm donation is at present achieved by insemination either in the uterus or in vitro, always from ejaculated and washed spermatozoa. Then, the infectious risk only exists if the donor sperm is capable of transporting the virus or its DNA, either by adhesion or by integration. With CMV, HSV1 and HSV2, medically assisted procreation in couples (AI or IVF-ET) does not increase the risk of viral contamination as compared with natural procreation, except possibly the cases of surgical procedure to pick up testicular sperm to be used in ICSI. Animal experiments show that, even if viral material is introduced in the oocyte, it may be eliminated from the embryo, at least for CMV.