TTV viral load as a biomarker of immune status in renal transplant patients – detected by home brew PCR and R-Gene® kit (bioMerieux)

REYES, NOELIA SOLEDAD; GARCIA GONZALO; SCHWALD ISABEL; GERVASIO SOLER PUJOL; NATALIA BOCCIA; HERMIDA ELIANA; CARLOS DIAZ; ECHAVARRIA MARCELA; LAHAM GUSTAVO; JARA RAQUEL; RICARTE CARMEN; CARBALLAL, GUADALUPE

Conferencia; 24th Annual Conference of the European Society for Clinical Virology; 2022

TTV viral load as a biomarker of immune status in renal transplant patients – detected by home brew PCRand R-Gene® kit (bioMerieux)N.S. Reyes1, G. Laham2, N. Boccia2, G. García2, R. Jara1, E. Hermida1, C. Ricarte1, C. Diaz2, G. Soler Pujol2,G. Carballal 1ƚ , M. Echavarria 1, 31- Virology Unit (CEMIC‐CONICET), Centro de Educación Médica e Investigaciones Clínicas University Hospital (CEMIC), 2- Departmentof Nephrology, CEMIC University Hospital, 3 Virology Laboratory, CEMICKey Words: TTV, prevalence, viral load, renal transplant, immune statusBackgroundTTV is small non enveloped DNA nonpathogenic virus that is highly prevalent in the general population(90%).The aim of this study was to compare TTV viral load with a homebrew PCR versus a commercial kit (TTV-RGene®, bioMerieux). Prevalence of TTV in plasma samples, viral load kinetics and their relationship withimmune status were also determined.MethodsA total of 647 plasma samples were obtained from 82 patients before and during the first year after renaltransplantation (RTx).TTV was detected and quantified by real time PCR using primers that amplify a highly conserved region of the5´UTR (Maggi et al., 2003), and the TTV R-GENE® KIT (bioMerieux).Qualitative and quantitative analyses were performed for both assays.ResultsTTV was detected with homebrew PCR in 61/77 (79.2%) and with TTV-R-Gene in 59/77 (76.6%) patientsbefore RTx, median viral load was 2.9 Log 10 copies/mL and 2.8 Log 10 copies/mL, respectively. Prevalence post-transplant was 100% with both PCR.TTV median viral load increased until day +90, reaching its maximum value, 6.5 and 6.1 Log 10 copies/mL withTTV homebrew and TTV R Gene PCR, respectively.491/647 (76%) samples were identified concordantly: 475 were positive and 41 were negative in bothmethods. As for the remaining samples, 27 were only positive with home brew PCR, and 11 were onlypositive with R-gene (Sensibility: 95.4% and Specificity: 81.4%).The correlation between the assays (R 2 : 0.80, p< 0.0001) was statically significant.Median viral load +180 days post-RTx were significantly lower in those patients who rejected compared tothose who did not, 3.2 vs. 6.0 Log 10 copies/mL (p=0.0305). Same trend was observed at +90 days, 6.5 vs. 6.1Log 10 copies/mL but not statistical significant.On day +90, TTV median viral load was higher in those patients with BKV infection compared to patientswithout infection (7.1 and 6.5 Log 10 copies/mL, respectively). Similar results were found at day +90 in patientswith CMV infection and without infection (6.9 and 6.5 Log 10 copies/mL, respectively). These differences werenot statistically significant.The median age of the cohort was 50.3 years old and 48% were male. 67 patients received a deceased donorgraft, 91,5% had thymoglobulin for immunosuppression induction and 100% received steroids, tacrolimusand mycophenolic acid for maintenance. No patient lost the graft a year after RTx.ConclusionsTTV prevalence before transplantation was lower than after transplantation. TTV prevalence during thisperiod may represent general TTV prevalence in Argentina.The correlation between TTV homebrew and TTV R Gene was high.