Project description:Limited understanding of the immunopathogenesis of human herpesvirus 6B (HHV-6B) has prevented its acceptance as a pulmonary pathogen after hematopoietic cell transplantation (HCT). We conducted a prospective multicenter study of patients undergoing bronchoalveolar lavage (BAL) for pneumonia after allogeneic HCT. We tested blood and BAL fluid (BALF) for HHV-6B DNA and mRNA transcripts associated with lytic infection and performed RNA-seq on paired blood. Among 116 participants, HHV-6B DNA was detected in 37% of BALs, 49% of which had HHV-6B mRNA detection. We established an HHV-6B DNA threshold (≥2.3 log10copies/ml in BALF) that was highly predictive of HHV-6B mRNA detection and increased risk for death from respiratory failure (adjusted HR, 2.35; 95% CI, 1.08-5.11). Participants with HHV-6B DNA in BALF exhibited distinct host gene expression signatures, notable for enriched interferon signaling pathways in participants clinically diagnosed with idiopathic pneumonia. These data implicate HHV-6B as a pulmonary pathogen after allogeneic HCT.
Project description:Tumor induction by Agrobacterium is due to transfer of T-DNA genes. We study the 6b T-DNA oncogene that induces tumors on species like Nicotiana glauca, but for which no precise growth induction mechanism has been found sofar. The 6b gene belongs to a larger group of T-DNA genes including rolB, rolC and orf13, no homologies are known with other genes. In N. tabacum, 6b modifies responses to auxins and cytokinins and induces strong morphological changes including cell enlargement, abnormal division, double flowers, enations and root shortening (Helfer et al., 2003, Grémillon et al., 2004). Others have localized 6b and rolB proteins in the nucleus, where they could modify transcription (Kitakura et al., 2002, Moriuchi et al., 2004). Recently, we developed a system to study early 6b-induced growth changes, using a dexamethasone-inducible 6b gene (dex-T-6b). Leaves of homozygous dex-T-6b plants are infiltrated with a 10 mM MgSO4 solution, with or without 20 micromolar dex. In the presence of dex, a reproducible increase in glucose and fructose concentrations is observed. Such changes are also found in cultured leaf discs and in that case accompanied by an increase in expansion. 6b-induced changes are detected as early as 7 hours after dex infiltration. Western analysis shows that dex-T-6b plants have undetectable 6b protein levels without induction, and rapidly accumulate 6b protein upon induction. We propose to study gene expression in induced and non-induced leaves at different times of induction: 0-3-6-9 and 12 hours. The data will be used to establish whether the 6b gene induces specific genes, and whether these genes are involved in hexose changes and cell expansion. We will also test the effect of infiltrating tobacco leaves with 10 mM MgSO4 by comparison with non-infiltrated leaf tissues in order to correct for changes due to the infiltration procedure. Keywords: Reference design
