Determining the presence of Torque-Teno virus in kidney transplant patients
Romina Bonaventura3, Martin Ajzenszlos4, Raño Julieta2, Cisterna Daniel3, Daniela Beltran2, Michelle Paredes2, Marcelo Carpio2, Lourdes Panelli2, Miguel Raño2, Fernando Margulis2, Elena Maiolo4, Ruben Schiavelli1.
1Chief Of Nephrolgy and Renal transplant, Hospital General de Agudos Cosme Argerich , Caba, Argentina; 2Devision of Nephrology and Renal Transplant , Hospital General de Agudos Cosme Argerich , Caba, Argentina; 3Servicio de Neurovirosis, Departamneto de Virología, Instituto Nacional de Enfermedades Infecciosas, ANLIS “C.G. Malbrán”, Caba, Argentina; 4Unidad de Infectología, Hospital General de Agudos Cosme Argerich , Caba, Argentina
Introduction: Introducing immune monitoring strategies in the clinical practice when following up transplant patients may minimize infectious and immunological events by individualizing treatments. One of the agents explored in this monitoring is torque teno virus (TTV). TTV is a small non-enveloped, circular single-stranded DNA virus and is a member of the Anello virus family. Primary infection occurs at an early age, followed by a latent infection, mainly in peripheral blood mononuclear cells with a prevalence of over 90%. Thus far, it has not been possible to prove any directly attributable pathogenic effect in human beings. Several studies have shown that reactivation of latent infection by anellovirus is more frequent in patients with chronic debilitating diseases, cancer, HIV infection, and in organ transplant recipients. TTV is diagnosed with a real-time PCR assay (rt-PCR), and cycle threshold (Ct) values of an RT‑PCR assay refer to the number of cycles needed to amplify viral DNA to reach a detectable level.
Objective: To describe the behavior of TTV Ct values in kidney transplant patients with infections (iKTPs), using stable kidney transplant patients (sKTPs) and healthy individuals (HIs) as control groups.
Methods: A single plasma sample of each individual from the three groups under study was processed. DNA was extracted with silica columns and the presence of TTV was subsequently determined by means of an rt-PCR using a specific probe (TaqMan chemistry). Student’s t-test was used, analyzing the Ct values for each group; a p-value less than 0.05 was considered statistically significant.
Results: Fifty-seven percent of the Ps studied were women. The average age of iKTPs and sKTPs was 54 and 50 years, respectively. The period of time after transplantation was 27 months (4-57) for iKTPs and 112 months for sKTPs.
The infections of iKTPs were:
A total of 23 plasma samples were processed: 5 iKTPs, 7 sKTPs and 11 HIs. Seventy-eight percent (18 Ps) tested positive for TTV. Positivity for the iKTP group was 100%, for sKTPs, 71% and for HIs, 73%. The average Ct values observed were 22.6 for the iKTP group, 30.1 for sKTPs and 31 for HIs. When comparing the Ct values for iKTPs vs. sKTPs and for iKTPs vs. HIs, we obtained P = 0.013 and 0.003, respectively.
Conclusion: Patients with severe infections, compared to patients from both control groups, had a significantly lower Ct average, which would be associated with a higher TTV viral load. Further studies with a larger number of patients are required to check the utility of this determination when monitoring the immunosuppressive state.
