TTV VIRAL LOAD WITH R-GENE® KIT VS HOME BREW PCR IN PLASMA PRE-TRANSPLANT AND FIRST YEAR POST-TRANSPLANTATION

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

Simposio; 36th Clinical Virology Symposium.; 2022

BackgroundTTV is small non enveloped DNA nonpathogenic virus that is highly prevalent in the general population(90%). TTV has been postulated as a surrogate marker of immunosuppression in transplant patients. TTVstandardization is needed to determine comparable viral loads between different assays.The aim of this study was to compare viral load of TTV with a homebrew PCR versus a commercial PCR(TTV-R Gene®, Biomerieux) and determine the prevalence of TTV in plasma samples from patients beforeand after a year of renal transplantation.MethodsFrom November 2018 to July 2020, 100 renal transplantations were performed at CEMIC UniversityHospital Buenos Aires, Argentina.A total of 510 plasma samples were obtained before and during the first year after transplantation of 68patients. TTV was detected by real time PCR using primers that amplify a highly conserved region of the5´non-coding region from all TTV species (Maggi et al., 2003) and using the TTV R-GENE® KIT(Biomerieux).The viral load was calculated using a quantified plasmid.ResultsTTV was positive with homebrew PCR in 47/63 (74.6%) patients and with TTV-R Gene in 49/63 (77.6%)patients before transplantation, median viral load was 2.9 Log 10 copies/mL and 2.8 Log 10 copies/mLrespectively. Prevalence post-transplant was 100%.Median viral load +30, +90, +180, +270 and +365 days after transplantation with homebrew PCR was 4.6,6.5, 5.6, 4.5 and 5.0 Log 10 copies/mL, respectively and with TTV R Gene was 3.6, 6.1, 5.3, 4.2 and 4.8 Log 10copies/mL, respectively.The median age of 63 patients was 50.3 years old and 41% were male. A total of fifty five patientsreceived a graft from a deceased donor, 94% received thymoglobulin for induction of immunosuppressionand 100% received steroids, tacrolimus and mycophenolic acid for maintenance. No patient lost the grafta year after transplantation.The correlation between both assays was statically significant (R 2 : 0.83, p< 0.0001) and the difference inmedian of viral load were statically significant in +90, +270 and +365 days (p< 0.0001, <0.001 and 0.043,respectively).ConclusionsTTV prevalence before transplantation was lower than after transplantation. TTV prevalence during thisperiod may represent general TTV prevalence in Argentina.The range of TTV viral load detected during de post-transplantation period varied from 4 to 8 Logs.The correlation between TTV homebrew and TTV R Gene was high.Standard quantify control is critical and necessary for comparison among different assays.