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Infectious complications are one of the main causes of morbidity and mortality in kidney transplantation and, to a large extent, will depend on the net state of immunosuppression achieved with treatment.
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 Anellovirus 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 a 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.
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). The study include iKTPs defined as those who required hospitalization at the time of infection, sKTPs defined as patients under outpatient control, and HIs defined as healthy without comorbidities. A plasma sample from each of the study groups was used.
Forty-seven patients were studied, TTV positivity was 90%. Only the positive ones were analyzed, so 42 patients were included, 14 iKTPs, 14 sKTPs and 14 HIs. Women were 28,6%, 28,6% and 57,1% for iKTPs, sKTPs and HIs respectively.
The average age was 43,3 years with no differences between the two transplant groups, while the group of healthy people were younger (35.07 years, P<0.05). The transplant time was 93 months (12-204) with no difference between the two groups.
Twenty-two infections were detected in the 14 iKTPs, which were: 6 CMV disease, 3 cryptococcosis, 1 disseminated chickenpox with pneumonitis, 1 urosepsis, 4 UTI, 1 pyelonephritis, 2 skin and soft tissue infections, 1 pulmonary nocardiosis, 1 cutaneous aspergillosis , 1 COVID-19 and 1 strongyloidiasis.
The average Ct values observed were 23,93 for the iKTPs group, 30.03 for sKTPs, and 32,35 for HIs.
When comparing the Ct values for iKTPs vs. sKTPs and for iKTPs vs. HIs, we obtained P =<0.05 and <0.05 respectively.
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. This could be an indication of decreasing immunosuppression without risk of rejection Further studies with a larger number of patients are required to check the utility of this determination when monitoring the immunosuppressive state.