Torque Teno Virus: A Biomarker of Immunosuppression

Balancing the adverse effects of over-immunosuppression such as infection and malignancy, to the risk of rejection, remains the central challenge for day-to-day clinical practice in transplantation. A quantitative measure of immunocompetence remains elusive, and in the absence of such markers, immunosuppression drug concentrations and clinical events, such as organ rejection, infection, malignancy etc. are used as surrogate markers of immunocompetence to guide therapy. As demonstrated in several studies, the Torque teno virus is widespread amongst the general population. In theory, if one suppresses the immune system, these viruses should multiply, resulting in a higher DNA level which can be detected by a simple blood test. Hence, the DNA level could be used as an indicator for the level of immunosuppression, along with the available blood tests to measure the level of toxicity of the said drugs. In this research to be done at the Royal London Hospital, the investigators aim to elucidate that the Torque teno virus is widely prevalent in an ethnically diverse East London kidney transplant recipient population by conducting the viral PCR on blood samples already collected during their routine clinic visits. The population will include all kidney transplant recipients in a two-year period. The investigators will measure the correlation between the TTV DNA level and drug concentrations of the immunosuppressive medications which will elucidate how the DNA levels are affected by different drug concentrations. The investigators will then measure the correlation between the TTV DNA levels, and the common adverse outcomes experienced by the transplant recipients, namely, patient death, loss of transplant organs, transplant rejection, rates of infection, and cancers in transplant patients by collecting data from patient records. These tests will help understand whether the Torque teno virus DNA levels can be used as a marker of immunosuppression in the general population in the UK.