Purpose: EBV and other herpesviruses are associated with a variety of malignancies. The EBV thymidine kinase (TK) is either not expressed or is expressed at very low levels in EBV-associated tumors. However, EBV-TK expression can be induced in vitro with several chemotherapeutic agents that promote viral lytic induction. The goal of this study is to image EBV-associated tumors by induction of viral TK expression with radiolabeled 2′-fluoro-2′-deoxy-β-d-5-iodouracil-arabinofuranoside (FIAU). Experimental Design: Immunoblot, luciferase reporter assay, and in vitro assay with [¹⁴C]FIAU were used to show the effects of bortezomib on the induction of lytic gene expression of EBV-associated tumor cells. In vivo imaging and ex vivo biodistribution studies with [¹²⁵I]FIAU on EBV-associated tumors were done to visualize and confirm, respectively, the EBV(+) tumor–specific effects of bortezomib. Results:In vitro assays with [¹⁴C]FIAU and ex vivo biodistribution studies with [¹²⁵I]FIAU showed that uptake and retention of radiolabeled FIAU was specific for cells that express EBV-TK. Planar gamma imaging of EBV(+) Burkitt's lymphoma xenografts in severe combined immunodeficient mice showed [¹²⁵I]FIAU localization within tumors following treatment with bortezomib. Conclusions: These results indicate the feasibility of imaging chemotherapy-mediated viral lytic induction by radiopharmaceutical-based techniques such as single photon emission computed tomography and positron emission tomography.

Tuberculous meningitis (TB meningitis) is the most severe form of tuberculosis (TB), requiring 12 months of multidrug treatment for cure, and is associated with high morbidity and mortality. High-dose rifampin (35 mg/kg/d) is safe and improves the bactericidal activity of the standard-dose (10 mg/kg/d) rifampin-containing TB regimen in pulmonary TB. However, there are conflicting clinical data regarding its benefit for TB meningitis, where outcomes may also be associated with intracerebral inflammation. We conducted cross-species studies in mice and rabbits, demonstrating that an intensified high-dose rifampin-containing regimen has significantly improved bactericidal activity for TB meningitis over the first-line, standard-dose rifampin regimen, without an increase in intracerebral inflammation. Positron emission tomography in live animals demonstrated spatially compartmentalized, lesion-specific pathology, with postmortem analyses showing discordant brain tissue and cerebrospinal fluid rifampin levels and inflammatory markers. Longitudinal multimodal imaging in the same cohort of animals during TB treatment as well as imaging studies in two cohorts of TB patients demonstrated that spatiotemporal changes in localized blood-brain barrier disruption in TB meningitis are an important driver of rifampin brain exposure. These data provide unique insights into the mechanisms underlying high-dose rifampin in TB meningitis with important implications for developing new antibiotic treatments for infections.

DO (HLA-DO, in human; murine H2-O) is a highly conserved nonclassical major histocompatibility complex class II (MHC II) accessory molecule mainly expressed in the thymic medulla and B cells. Previous reports have suggested possible links between DO and autoimmunity, Hepatitis C (HCV) infection, and cancer, but the mechanism of how DO contributes to these diseases remains unclear. Here, using a combination of various in vivo approaches, including peptide elution, mixed lymphocyte reaction, T-cell receptor (TCR) deep sequencing, tetramer-guided naïve CD4 T-cell precursor enumeration, and whole-body imaging, we report that DO affects the repertoire of presented self-peptides by B cells and thymic epithelium. DO induces differential effects on epitope presentation and thymic selection, thereby altering CD4 T-cell precursor frequencies. Our findings were validated in two autoimmune disease models by demonstrating that lack of DO increases autoreactivity and susceptibility to autoimmune disease development.

Whole body PET/CT imaging was performed using ¹²⁴I-iodo-DPA-713, a radioligand for the 18-kDa translocator protein (TSPO), to determine biodistribution and radiation dosimetry. Methods. Healthy subjects ages 18-65 years underwent whole body PET/CT imaging at either 4, 24 and 48 hours or 24, 48 and 72 hours after intravenous injection with ¹²⁴I-iodo-DPA-713. Time-activity curves were generated and used to calculate organ time-integrated activity coefficients for each subject. The resulting time-integrated activity coefficients provided input data for calculation of organ absorbed doses and effective dose for each subject using OLINDA. Subjects were genotyped for the TSPO polymorphism, rs6971, and plasma protein binding of ¹²⁴I-iodo-DPA-713 was measured. Results. Three male and three female adults with mean age of 40 ± 19 years were imaged. The mean administered activity and mass were 70.5 ± 5.1 (range, 62.4-78.1) MBq and 469 ± 34 (range, 416-520) ng respectively. There were no adverse or clinically detectable pharmacologic effects in any of the six subjects. No changes in vital signs, laboratory values or electrocardiograms were observed. ¹²⁴I-Iodo-DPA-713 cleared rapidly (4 hours post-injection) from the lungs with hepatic elimination and localization to the gastrointestinal tract. The mean effective dose over six subjects was 0.459 ± 0.127 mSv/MBq with the liver being the dose-limiting organ (0.924 ± 0.501 mGy/MBq). The percentage of free radiotracer in blood was ~30% at 30 and 60 minutes post-injection. Conclusion. Iodo-DPA-713 is cleared rapidly from the lungs with predominant hepatic elimination. It is safe and well-tolerated in healthy adult subjects.