Extended microbiological characterization of Göttingen minipigs: porcine cytomegalovirus and other viruses.

Background: To prevent transmission of zoonotic microorganisms from pig transplants to human recipients when performing xenotransplantation using pig cells, tissues, or organs, donor pigs have to be carefully characterized. Göttingen minipigs (GöMP) are often used for various biomedical investigations and are well characterized concerning the presence of numerous bacteria, fungi, viruses, and parasites. Recently, we studied the prevalence and expression of porcine endogenous retroviruses and the prevalence of hepatitis E virus (HEV) in GöMP. Here, we studied the presence of the porcine cytomegalovirus (PCMV) and porcine lymphotropic herpesviruses (PLHV) and extended testing for hepatitis E virus (HEV).

Methods: PCR, nested PCR, real-time PCR, real-time RT-PCR, and Western blot analyses were used to estimate the prevalence of PCMV, PLHV-1, PLHV-2, PLHV-3, and HEV.

Results: Using different PCR methods, and different source materials, PCMV was found in 10 of 26 adult GöMP, which had been derived originally by cesarean section and kept under specified pathogen-free conditions. Only highly sensitive methods gave positive results, not methods of lower sensitivity. The virus load in all positive animals was low (<100-200 copies per mL). PLHV-1, PLHV-2, and PLHV-3 were not detected by PCR; however, an anti-PLHV immune response was found in one of 10 animals tested by Western blot analyses. HEV was detected by RT-PCR in two of nine tested animals, but no anti-HEV immune response was observed.

Conclusion: Using highly sensitive methods, PCMV, HEV, and PLHV were found in some GöMP, suggesting that these viruses may be introduced through the placenta. The results show that highly sensitive methods are required to characterize pigs to be used for xenotransplantation to prevent virus transmission.