CRISPR/Cas9 cleavage of viral DNA efficiently suppresses hepatitis B virus

Chronic hepatitis B virus (HBV) infection is prevalent, deadly, and seldom cured due to the persistence of viral episomal DNA (cccDNA) in infected cells. Newly developed genome engineering tools may offer the ability to directly cleave viral DNA, thereby promoting viral clearance. Here, we show that the CRISPR/Cas9 system can specifically target and cleave conserved regions in the HBV genome, resulting in robust suppression of viral gene expression and replication. Upon sustained expression of Cas9 and appropriately chosen guide RNAs, we demonstrate cleavage of cccDNA by Cas9 and a dramatic reduction in both cccDNA and other parameters of viral gene expression and replication. Thus, we show that directly targeting viral episomal DNA is a novel therapeutic approach to control the virus and possibly cure patients.United States. National Institutes of Health (DK085713)National Cancer Institute (U.S.) (P30-CA14051)National Institute of Environmental Health Sciences (P30-ES002109)United States. National Institutes of Health (1K08DK101754

Risk of Stillbirth after Antepartum Hospitalization for Hypertensive Diseases of Pregnancy

Abstract Objective To determine if women with an antepartum admission for hypertensive diseases of pregnancy (HDP) were at increased risk for stillbirth. Study Design This study utilized the 2010 to 2014 Nationwide Readmissions Database. Antepartum admissions with HDP were identified and linked to subsequent delivery hospitalizations. Delivery hospitalizations with HDP without a preceding antepartum HDP admission were also identified. Risk for stillbirth, abruption, or both was compared between these two groups. Results An estimated 382,621 deliveries with an HDP diagnosis were identified of which 14,857 (3.9%) had a preceding antepartum admission for HDP. Stillbirth occurred in 7.8 per 1,000 delivery hospitalizations complicated by HDP with risk higher with a preceding HDP antepartum admission in both unadjusted (1.1 vs. 0.8%, risk ratios [RR] 1.46, 95% confidence interval [CI] 1.24–1.70) and adjusted (adjusted risk ratios [aRR] 1.24, 95% CI 1.06, 1.46) analyses. Abruption occurred in 19.6 per 1,000 delivery hospitalizations complicated by HDP with risk higher with a preceding HDP antepartum admission in both unadjusted (2.5 vs. 1.9%, RR 1.30, 95% CI 1.17–1.44) and adjusted (aRR 1.24, 95% CI 1.11, 1.37) analyses. Risk for combined abruption and stillbirth did not differ significantly. Conclusion In this analysis, prior antenatal hospitalization was associated with increased risk for stillbirth among women with HDP.</jats:p

C2c2 is a single-component programmable RNA-guided RNA-targeting CRISPR effector

The clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated genes (Cas) adaptive immune system defends microbes against foreign genetic elements via DNA or RNA-DNA interference. We characterize the class 2 type VI CRISPR-Cas effector C2c2 and demonstrate its RNA-guided ribonuclease function. C2c2 from the bacterium Leptotrichia shahii provides interference against RNA phage. In vitro biochemical analysis shows that C2c2 is guided by a single CRISPR RNA and can be programmed to cleave single-stranded RNA targets carrying complementary protospacers. In bacteria, C2c2 can be programmed to knock down specific mRNAs. Cleavage is mediated by catalytic residues in the two conserved Higher Eukaryotes and Prokaryotes Nucleotide-binding (HEPN) domains, mutations of which generate catalytically inactive RNA-binding proteins. These results broaden our understanding of CRISPR-Cas systems and suggest that C2c2 can be used to develop new RNA-targeting tools.United States. Dept. of Energy (Computational Science Graduate Fellowship)Massachusetts Institute of Technology. Simons Center for the Social BrainNational Institute of General Medical Sciences (U.S.) (Award T32GM007753)National Institutes of Health (U.S.) (National Institute of Mental Health (U.S.) Grants 5DP1-MH100706 and 1R01-MH110049)National Science Foundation (U.S.)New York Stem Cell FoundationSimons FoundationPaul G. Allen Family FoundationVallee FoundationPoitras FoundationRobert MetcalfeDavid R. Chen