Major 5'terminally deleted enterovirus populations modulate type I IFN response in acute myocarditis patients and in human cultured cardiomyocytes.

Major 5'terminally deleted (5'TD) group-B enterovirus (EV-B) populations were identified in heart biopsies of patients with fulminant myocarditis or dilated cardiomyopathy suggesting that these 5'TD forms are key drivers of host-cell interaction in EV cardiac infections. To date, early emergence of EV-B 5'TD forms and its impact on type 1 IFN response during acute myocarditis remains unknown. Using quantitative RACE-PCR assay, we identified major EV-B 5'TD RNA populations in plasma or heart samples of acute myocarditis cases. Deletions identified within the 5' non-coding region of EV-B populations only affected secondary-structural elements of genomic RNA domain I and were distinguished in two major groups based on the extent of RNA structural deletions. Proportions of these two respective EV-B 5'TD population groups were positively or negatively correlated with IFN-ß levels in plasma samples of myocarditis patients. Transfection of synthetic CVB3/28 RNAs harboring various 5'terminal full-length or deleted sequences into human cultured cardiomyocytes demonstrated that viral genomic RNA domain I possessed essential immunomodulatory secondary-structural elements responsible for IFN-ß pathway induction. Overall, our results highlight the early emergence of major EVB-TD populations which deletions affecting secondary-structures of RNA domain I can modulate innate immune sensing mechanisms in cardiomyocytes of patients with acute myocarditis.

Characterization of quinolone resistance mechanisms in Enterobacteriaceae recovered from diseased companion animals in Europe.

ComPath is a European monitoring programme dedicated to the collection of bacterial pathogens from diseased dogs and cats to determine their antibiotic susceptibility. The objective was to characterize genetic determinants associated with quinolone resistance among 69 enrofloxacin non-wild type strains selected among 604 non-duplicate Enterobacteriaceae isolates collected in 10EU countries from 2008 to 2010: quinolone resistance determining region (QRDR) and plasmid-mediated quinolone resistance (PMQR). Among them, 17% (12/69) carried at least one PMQR (9/12 qnrB, qnrS or qnrD and 4/12 aac(6')-Ib-cr) and 83% (57/69) no PMQR. All the Klebsiella pneumoniae isolates chromosomally carried oqxAB . No qepA genes were detected. Eight strains did not carry any mutations in QRDR (4 PMQR-positive and 4 PMQR-negative strains). From the 12 PMQR-positive strains, 4 showed enrofloxacin MICs≤2µg/mL, and 8 MICs≥8µg/mL (resistant). These latter strains carried 1-5 mutations in QRDR, including a ParE I529L mutation. qnrD was found in 2 Proteus mirabilis and the plasmids were similar to pDIJ09-518a previously described. For the 57 non-PMQR strains, 29 strains showed MICs≤2µg/mL (4 with no QRDR mutations, 21 with 1 mutation in GyrA, 4 with 2 mutations in GyrA) and 28 showed enrofloxacin MICs≥8µg/mL carrying at least 2 mutations in QRDR, including a ParE I529L mutation for 2 Escherichia coli strains with a total of 5 QRDR mutations. No GyrB mutations were found. qnr was the major PMQR and qnrD was only detected in Proteus spp. Twelve strains carried at least 4 mutations.