[Research of porcine endogenous retrovirus in Shaziling pigs]

To provide basic parameters of evaluating the biological safety of xenotransplantation from pig to human, ear tissues from 31 individuals were randomly collected from a Shazi Ling pig population. PCR and RT-PCR were performed to detect porcine endogenous retrovirus (PERV) proviral DNA and mRNA respectively. The sensitivity of the PCR was evaluated using a positive control. To study tissue distribution, RT-PCR of pol, gag and env was performed in the kidney, heart, liver, lung and spleen of 3 individuals. Finally, env-A, env-B and env-C were amplified, sequenced and analyzed using the BLAST software in NCBI (National Center for Biotechnology Information). The results showed PERV proviral DNA and mRNA could be detected in all 31 individuals by PCR and RT-PCR, respectively. env-A, env-B and env-C were only detected in 2 individuals, while in the other 29 individuals, only env-A and env-B but not env-C was detected. The quantity of DNA in PCR amplification of PERV genes should be more than 15 ng. RT-PCR results showed gag, pol, env-A and env-B were expressed in the kidney, heart, liver, lung and spleen of all 3 individuals, but env-C was not. Sequencing of env genes in Shazi Ling pigs revealed that while there was no difference in env-A sequence when compared to other herd in GenBank, there were 2 and 10 bp differences in the sequences of env-B and env-C respectively, suggesting that env gene is polymorphic in different pig strains. PERV exists in the Shazi Ling pig population and the predominant subtype is PERV-A, B. The distribution of PERV displays no significant tissue specificity and env-C is absent in 93.5% (29/31) of the individuals. The results indicate that Shazi Ling pig may have great potential value as a candidate in xenotransplantation.