Sensitive and specific immunological detection methods for porcine endogenous retroviruses applicable to experimental and clinical xenotransplantation

The use of organs from transgenic pigs for xenotransplantation may be assoc iated with the risk of transmission of microorganisms, especially when the transgenic pigs express human proteins influencing complement activation. T he porcine endogenous retroviruses (PERVs) are of particular concern as the y can infect human cells in vitro. However, it is unknown whether PERVs can infect transplant recipients in vivo and, if so, whether they are pathogen ic. It is therefore essential for experimental and clinical xenotransplanta tion procedures that specific and sensitive screening methods for PERVs are established. We developed Western blot and enzyme-linked immunosorbant ass ays (ELISA) based on purified PERVs produced by pig and human cells or reco mbinant viral protein and synthetic peptides corresponding to PERVs' transm embrane envelope protein, respectively. PERV-specific anti-sera generated a gainst purified virus particles, purified viral proteins and synthetic pept ides served as positive controls. Both assays were used for screening the s era of healthy blood donors, pregnant women, patients treated with pig tiss ues, and butchers with extensive contact to living porcine material to dete ct antibodies against PERV. None of the individuals showed an antibody patt ern characteristic for retroviral infections. Some individuals had antibodi es reactive against the major capsid protein p27, against smaller viral pro teins of the group specific antigen (Gag) in Western blot assays, or agains t peptides in the ELISA, probably due to cross-reactivity. Here, we present specific and highly sensitive screening methods applicable for future xeno transplantation procedures, but using these methods we found no evidence of PERV-infection among humans potentially at risk.