Prof Ralf R. Tönjes, Ph.D.
Ralf Reinhard Tönjes (RRT; German) is life scientist and regulator of medicinal products at Paul-Ehrlich-Institut (PEI), Federal Institute for Vaccines and Biomedicines, Division of Haematology, Cell and Gene Therapy, Langen, Germany.
RRT received his M.S. degree in Biology and Germanistics (1983) and his Ph.D. degree in Biology (1986) from Philipps University, Marburg, Germany. His thesis involved molecular cloning and analyses of histone genes and proteins for chromatin studies. As a researcher, he worked at Fraunhofer Institute, Hannover, Germany, and at Rockefeller University, New York, United States (1986-1991). His research interests included the liver specific regulation of genes in mutant as well as genetically modified mice.
At PEI, RRT was head of three sections since 1991. At current, in the restructured organisation at PEI, he became head of subsection “Tissue Preparations, Xenotransplantation”. As such, RRT is in charge of evaluations of medicinal products including human tissue preparations and xenogeneic cell therapeutics according to European and German legislations. Simultaneously, RRT’s area of experimental research is the safety of xenotransplantation. In particular, he concentrates on the characterization of porcine microbes including viruses and zoonotic agents as well as endogenous retroviruses and retroelements. In addition, RRT is involved in the non-clinical testing of xenotransplants using genetically modified animals.
In 1998, RRT founded the German working group for xenotransplantation (DAX) together with Dr. Joachim Denner.
Since 2002, RRT teaches as an adjunct professor and lecturer for biochemistry at Goethe University, Frankfurt/Main, Germany.
Since 2005, RRT is representative of Germany at World Health Organization (WHO) and at European Medicinal Agency (EMA) for global consultations on regulatory requirements for clinical trials of xenotransplantation. Since 2008, RRT is German representative for Tissues & Cells (T&C) at the European Commission, National Competent Authorities, Substances of Human Origin (SoHO). Since 2012, RRT is German representative for T&C at the European Committee on Organ Transplantation (CD-P-TO), EDQM, Council of Europe. Since 2022, RRT is German Member of SoHO Network, SoHO National Focal Point for Blood, Human Organs, MAR and/or Tissues and Cells. Since 2023, RRT is expert for T&C and Member of SoHO Network Coordination Committee (NCC) within the SoHO National Focal Points.
Isolation and functional analysis of an ecotropic porcine endogenous retrovirus PERV-C from a Yucatan SLA D/D haplotype inbred miniature swine
Michael Rodrigues Costa1, Nicole Fischer1, Antonia Gronewold1, Barbara Gulich1, Antonia W Godehardt1, Ralf R Tönjes1.
1Division of Haematology, Cell and Gene Therapy, Paul-Ehrlich-Institut, Federal Institute for Vaccines and Biomedicines, Langen, Germany
Introduction: Yucatan SLAD/D (SLA, swine leukocyte antigen) haplotype inbred miniature swine are candidates as organ donors for xenotransplantation. Porcine endogenous retroviruses (PERV) inherit infectious potential if pig cells, tissues, or organs were transplanted to immunosuppressed human recipients. Particularly, ecotropic PERV-C that could recombine with PERV-A to highly replication-competent human-tropic PERV-A/C should be excluded from pig breeds designed for xenotransplantation. SLAD/D pigs do not bear replication-competent PERV-A and –B, even if they carry PERV-C. Therefore, when using SLAD/D pigs, absence and/or elimination of genomic PERV-C is required to fully guarantee patient infectious safety in pig-to-human xenotransplantation.
Methods: Based upon the hypothesis that SLAD/D pigs inherit a proviral PERV-C, a bacteriophage lambda library of a female pig was generated and screened. PERV-C clone number 561 was isolated. The provirus, truncated in the envelope (env) and missing the 3’-LTR due to cloning in lambda, was complemented by PCR, and the recombinants were functionally characterized. Recombinant clone PERV-C(561) was chromosomally mapped by its 5’-proviral flanking sequences.
Results: Transfection of recombinant clone PERV-C(561) promoted retroviral expression including reverse transcriptase (RT) in ST-IOWA cells. Over time, stable transfectants of recombinant PERV-C(561) confirmed an increased infectivity in vitro compared to other PERV-C. Full-length PCR using 5’-and 3’-flanking primers specific to the genomic PERV-C(561) locus verified that this specific SLAD/D haplotype pig harbors at least one full-length PERV-C provirus. The chromosomal location is different from that of the previously described PERV-C(1312) provirus, which was derived from the porcine cell-line MAX-T.
Conclusion: The sequence data presented here provide further knowledge about PERV-C infectivity and contribute to targeted knockout in order to generate PERV-C-free founder animals.
This work was supported by grant TRR127 TO 117/1-4 from the Deutsche Forschungsgemeinschaft, DFG, Bonn, Germany..
