Evaluation of biosafety of equine amniotic membranes for allogeneic use – a pilot study using PCR pathogens screening on peripheric maternal blood and paired fetal adnexa

International audienceTransplantation of amniotic membranes (AM) is increasingly used for equine tissue reconstruction. However, there is currently no published data on systematic screening of donor mares for infectious diseases, in contrast to human medicine. To minimize the risk of iatrogenic donor‐borne contamination, we questioned the biosafety of equine AM. We hypothesized that the processed amnion layer of AM is less exposed than peripheric maternal blood (PMB) to pathogens, aiming to assess the risk of vertical contamination of AM from mares potentially carrying common equine infectious agents. The study was conducted on 6 fetal membrane collections during foaling seasons 2016–2017. Systematic Coggins test and PCR screening for B. caballi, T. equi, A. phagocytophilum, B. burgdorferi, Leptospira spp, Mycoplasma spp, R. equi, equine arteritis virus, equine herpesviruses type 1, 2, 4 and 5 were performed on PMB. The amnion layer was isolated, processed and frozen down at −80°C. Mycoplasma PCR screening and bacteriological and fungal cultures were performed to exclude environmental contamination. In case of one or more positive PCR result(s) on PMB, a PCR analysis for the detected pathogen(s) was conducted on a biopsy sample of the associated AM. All PMB samples were PCR positive for at least one pathogen: 3 for EHV2, 3 for EHV2 and EHV5. All AM samples were negative for these specific pathogens. In conclusion of this pilot study, processed equine AM appear free of donor‐borne contamination, even for vertically communicable pathogens such as gammaherpesviruses. More data is needed to assess the residual risk of contamination of amnion tissue when the mare is positive for one or more infectious agent(s). Also, emerging pathogens like hepaciviruses should be included in the future