No evidence for infection of target cell lines with porcine endogenous retrovirus (PERV) from islet cells
Background The increasing interest in the use of pig tissue for xenotransplantation has stimulated an intensive microbiological study of pigs. It has been shown that pig endogenous retrovirus (PERV) is present and actively transcribed in most porcine tissues and can produce mature viral particles capable of infecting human cells in vitro. Islet cells have the lowest level of PERV expression compared with other pig tissues, although both neonatal and adult islet cells have been shown to infect target cell lines or SCID mice in the experimental setting. Islets isolated from certain pig phenotypes have not been infectious. The possibility of different infectivities of PERV from different pig breeds and from individual pigs is extensively discussed in the literature on xenotransplant safety.
Aim The aim of the present study was to look for evidence of PERV transmission in vitro into target cell lines and to examine the infectivity of tissues obtained from a specific donor pig herd.
Materials and methods The following cell lines were used in the experiments: HEK293, MV1LU, SC11, MDCK, Jurkat, LLCMK2, Hep 2, PK15, PHA-stimulated pig PBMC, pig islet cells. Nested PCR and RT-PCR were used for PERV detection. To exclude microchimerism, cytochrome oxidase (COII) was assayed by nested PCR and RT-PCR.
Results We established that the PK15 cell line was unable to infect MDCK, SC11, LLCMK2, Jurkat or Hep2 cell lines. We showed that islet cells expressed all three PERV env classes. However, primary islet cell cultures from newborn piglets were not able to infect the standard target cell lines HEK293 or MV1LU as well as other tested cell lines such as MDCK, SC11, LLCMK2, Jurkat or Hep2. Similar results were obtained with PHA-stimulated pig PBMC from adults and neonatal pigs.
Conclusions Primary cultures of islets cells and PHA-stimulated PBMC from the source herd were unable to infect target cell lines despite the prolonged viability of islet cell cultures and the expression of all three classes of PERV.