To better understand the molecular events involved in the origin of new pathogenic bacteria, we studied the evolution of a highly virulent clone of serotype M1 group A Streptococcus (GAS). Genomic, DNA-DNA microarray, and single-nucleotide polymorphism analyses indicated that this clone evolved through a series of horizontal gene transfer events that involved (1) the acquisition of prophages encoding streptococcal pyrogenic exotoxin A and extracellular DNases and (2) the reciprocal recombination of a 36-kb chromosomal region encoding the extracellular toxins NAD+-glycohydrolase (NADase) and streptolysin O (SLO). These gene transfer events were associated with significantly increased production of SLO and NADase. Virtual identity in the 36-kb region present in contemporary serotype M1 and M12 isolates suggests that a serotype M12 strain served as the donor of this region. Multiple horizontal gene transfer events were a crucial factor in the evolutionary origin and emergence of a very abundant contemporary clone of serotype M1 GAS.

BACKGROUND. Hepatitis C virus (HCV) infects approximately 170 million people worldwide and may lead to cirrhosis and hepatocellular carcinoma in chronically infected individuals. Treatment is rapidly evolving from IFN-α-based therapies to IFN-α-free regimens that consist of directly acting antiviral agents (DAAs), which demonstrate improved efficacy and tolerability in clinical trials. Virologic relapse after DAA therapy is a common cause of treatment failure; however, it is not clear why relapse occurs or whether certain individuals are more prone to recurrent viremia. METHODS.We conducted a clinical trial using the DAA sofosbuvir plus ribavirin (SOF/RBV) and performed detailed mRNA expression analysis in liver and peripheral blood from patients who achieved either a sustained virologic response (SVR) or relapsed. RESULTS.On-treatment viral clearance was accompanied by rapid downregulation of IFN-stimulated genes (ISGs) in liver and blood, regardless of treatment outcome. Analysis of paired pretreatment and end of treatment (EOT) liver biopsies from SVR patients showed that viral clearance was accompanied by decreased expression of type II and III IFNs, but unexpectedly increased expression of the type I IFN IFNA2. mRNA expression of ISGs was higher in EOT liver biopsies of patients who achieved SVR than in patients who later relapsed. CONCLUSION.These results suggest that restoration of type I intrahepatic IFN signaling by EOT may facilitate HCV eradication and prevention of relapse upon withdrawal of SOF/RBV. TRIAL REGISTRATION. ClinicalTrials.gov NCT01441180. FUNDING. Intramural Programs of the National Institute of Allergy and Infectious The Journal of Clinical Investigation C l i n i C a l M e d i C i n e3 3 5 3 jci.orgVolume 124 Number 8 August 2014We next evaluated on-treatment serum protein levels of select chemokines and cytokines and observed similar expression at baseline and during treatment comparing patients who achieved SVR versus those who relapsed (Supplemental Table 3). Serum levels of the IFN-inducible cytokine IP-10, the protein product of the CXCL10 gene that was downregulated in liver (Figure 2A), correlated significantly with baseline viral load ( Figure 3A). Expression decreased rapidly on-treatment, regardless of treatment outcome, and increased with relapse ( Figure 3B). Viral kinetic and IP-10 decline were significantly correlated ( Figure 3C and Table 1). IL-10 and IFN-γ decreased modestly during treatment, while expression of most other proteins did not change, including TGF-β1 and TIMP1, which are associated with hepatic fibrosis (Supplemental Table 3 and ref. 25).To assess whether a similar pattern of gene expression changes could be observed in the periphery, we performed microarray mRNA analysis in PBMCs collected before treatment, early in treatment (day 6-11), and at EOT (week 24) and identified a significant decrease of IFN signaling during treatment (Supplemental Figure 2 and Supplemental Table 4). qRT-PCR analysis in PBMCs confirmed rapid and sustained downregulation of I...

A microorganism (Dermacantor andersoni symbiont [DAS]) infecting Rocky Mountain wood ticks (D. andersoni) collected in the Bitterroot Mountains of western Montana was characterized as an endosymbiont belonging to the genus Francisella. Previously described as Wolbachia like, the organism's DNA was amplified from both naturally infected tick ovarial tissues and Vero cell cultures by PCR assay with primer sets derived from eubacterial 16S ribosomal DNA (rDNA) and Francisella membrane protein genes. The 16S rDNA gene sequence of the DAS was most similar (95.4%) to that of Francisella tularensis subsp. tularensis. Through a combination of Giménez staining, PCR assay, and restriction fragment length polymorphism analysis, 102 of 108 female ticks collected from 1992 to 1996 were infected. Transovarial transmission to female progeny was 95.6%, but we found no evidence of horizontal transmission.