Evidence of porcine endogenous retroviruses in porcine factor VIII and evaluation of transmission to recipients with hemophilia

Since 1984, unheated porcine clotting factor VIII (Hyate:C) has been used t o treat severe bleeding episodes in persons with hemophilia who have antibo dies to human clotting factor. We document the presence of porcine endogeno us retrovirus (PERV) in plasma samples of pigs and in clinical lots of Hyat e:C. Both gag and pol PERV RNA sequences were detected by reverse-transcrip tase (RT) polymerase chain reaction in 13 of 13 lots of Hyate:C tested. Amo ng 10 of these lots, RT activity also was detected, which confirms the pres ence of retroviral particles. To assess the transmission of PERV to Hyate:C recipients, we tested serum specimens from 88 recipients of Hyate: C and 2 3 noninfused control subjects for anti-PERV antibodies by using a Western b lot assay. None of the samples was positive. Our data document that PERV pa rticles are a common contaminant of Hyate:C products and suggest that the r isk of PERV transmission from these percutaneous exposures is very low.