1Université Grenoble Alpes IBS, HIV & Persisting viruses, Grenoble Cedex, France, 2University, Hospital, Université Grenoble Alpes, Unit of Virology, Grenoble Cedex, France, 3University Hospital, Université Grenoble Alpes, Unit of Virology, Grenoble Cedex, France, 4Hôpital Saint-Louis, AP-HP, Université Paris-Diderot, Unit of Clinical Hematology, Paris, France, 5University Hospital, Université de Nantes, Unit of Nephrology & Clinical Immunology, Nantes, France
Background: The ZEBRA immediate-early protein (IE encoded by the BZLF1 gene), is the major transcription factor of EBV, expressed upon EBV lytic cycle activation. An increasing body of studies highlighted the critical role of EBV lytic infection as a risk factor for lymphoproliferative disorders like post-transplant lymphoproliferative disease (PTLD). Moreover, Several experiments highlighted the role of the IE lytic viral protein expression in the lymphomagenesis in immunocompromised mice.The current report describes the quantification of the circulating EBV ZEBRA protein (sZEBRA) in serum samples from transplanted patients, the comparison with the EBV qPCR and its clinical significance.
Methods: We studied 66 transplanted patients (35 PTLD and 31 controls) retrospectively selected patients from different hospitals in France: 26 with kidney, 6 with HSC, 3 with lung transplants All patients were monitored by means of routine viral testing, resulting in 322 serum specimens. PTLD diagnosis was based on examining histological material, with lesions classified according to the WHO Classification of tumors. Association with EBV was confirmed by in situ staining for EBER. Serum and plasma samples were collected for the sZEBRA ELISA and EBV load, respectively (Habib M et al. Nature Sci Reports 2017).
Results: The majority of PTLD tumors were monomorphic B-cell lymphomas and EBV-positive. Nine patients experienced atypical PTLD forms (3 Hodgkin's lymphomas, 2 T-cell lymphomas, 2 Burkitt's lymphomas, and 2 mantle cell lymphomas). In the patients who developed a pathologically-confirmed PTLD, the mean sZEBRA value in cases, was 399 ng/mL +/− 141 versus 53ng/mL +/− 7 in patients who did not (p < 0,001). Based on their clinico-pathological characteristics, we divided our patients in two groups according to the PTLD occurrence (16 patients with early-onset PTLD versus 19 patients with late onset PTLD). At diagnosis, the mean (+/− SEM) sZEBRA value in patients with early-onset PTLD was 787.9 +/− 271.7 ng/mL versus 51.47 +/− 4.46 ng/mL in the patients with late-onset PTLD (p= 0.0056). All the lymphomas occurring in HSC transplant patients were early-onset PTLD (12 out of 16). We retrospectively followed-up the sZEBRA-positive patients with multiple serum specimens available. The median follow-up was 8 months (range: 1 month −24 months). In these selected patients, it is worth noticing the precocity of sZEBRA compared with EBV DNA (on average within 10 weeks preceding PTLD diagnosis). Concerning patient follow-up, it is interesting to note that sZEBRA protein could be detected during periods in which EBV DNAemia was not detectable when using qPCR.
Conclusions: This is the first report pertaining to the detection of a soluble form of the ZEBRA protein in serum specimens, as well as the first analysis on the replicative nature of EBV by using this putative new biomarker in PTLD patients. In the patients with sZEBRA ≥ 100 ng/mL the test has a positive predictive value of 80% for PTLD. Similar results (sZEBRA detection) were obtained in experiments in the NSG mice model. These results showed that lytic EBV infection can be detected in what has been dogmatically believed to be latent-EBV driven B-cell replication.
Disclosure: Nothing to declare