Expression of porcine endogenous retroviruses (PERV) in different organs of a pig.

Porcine endogenous retroviruses (PERVs) represent a particular risk for xenotransplantation using pig cells, tissues or organs. PERVs are integrated in the genome of all pig strains and can be released as particles that infect human cells. We performed for the first time a systematic analysis of PERV expression in different organs of a miniature pig using in parallel quantitative real-time RT-PCR, Western blot analysis, and immunohistochemistry. All three types of PERV, PERV-A, PERV-B and PERV-C were present in the germ line of the animal. In addition, recombinant PERV-A/C were detected in some tissues, but not in the germ line. Expression of the viral full-length and spliced mRNA and proteins was found in many organs, but at different levels. A high expression was found in lymphoid organs.