Genome editing via CRISPR/Cas9 has become an efficient and reliable way to make precise, targeted changes to the genome of living cells. CXCR4 is a co-receptor for the human immunodeficiency virus type 1 (HIV-1) infection and has been considered as an important therapeutic target for AIDS. CXCR4 mediates viral entry into human CD4+ cells by binding to envelope protein, gp120. Here, we show that human CXCR4 gene is efficiently disrupted by CRISPR/Cas9-mediated genome editing, leading to HIV-1 resistance of human primary CD4+ T cells. We also show that the Cas9-mediated ablation of CXCR4 demonstrated high specificity and negligible off-target effects without affecting cell division and propagation. The precise and efficient genome editing of CXCR4 will provide a new strategy for therapeutic application against HIV-1 infection.

Background As an alternative biomarker of intrahepatic covalently closed circular DNA (cccDNA) transcriptional activity, hepatitis B virus (HBV) RNA may evolve during long-lasting virus-host interactions during chronic hepatitis B viral infection. The distribution pattern of serum HBV RNA levels in the natural course of chronic HBV infection remains unclear. The aim of this study was to evaluate the levels of HBV RNA during the natural course of CHB and the role in distinguishing the natural history of HBV infection. Methods A total of 291 treatment-naïve chronic HBV carriers were enrolled. Based on the clinical, biochemical, serological, and histological data as well as HBV DNA levels, patients were classified into the following four categories: the immune-tolerant phase (IT, n = 35), HBeAg-positive immune-active phase (EPIA, n = 121), inactive chronic hepatitis B(ICH, n = 58) and HBeAg-negative immune reactive hepatitis (ENH, n = 77). The parameters and distribution patterns of serum HBV RNA were evaluated in relation to viral replication status, immune phase, disease category and Child-Pugh class. The relationships between serum HBV RNA and other serum hepatitis B viral markers were also analyzed. Results Serum HBV RNA levels were significantly lower in the HBeAg-negative patients compared to those in the HBeAg-positive patients, with the lowest levels seen in inactive carriers. In HBeAg-negative patients, serum HBV RNA levels increased if there is reactivation to active hepatitis and showed obvious superiority for the combination of serum HBV DNA (cutoff>3.39 Log copies/mL) and HBsAg (cutoff>2.74 Log IU/mL) in discriminating between ‘HBeAg-negative immune reactive’ phase and inactive chronic hepatitis B phases of HBeAg-negative chronic HBV infection. Serum HBV RNA levels were positively correlated with serum HBV DNA and HBsAg levels in all chronic HBV-infected patients. A stratified analysis revealed that a correlation between serum HBV RNA and HBV DNA or HBsAg was present in HBeAg-positive patients; however, in HBeAg-negative patients, serum HBV RNA was positively correlated with HBV DNA only. Conclusion During the natural course of chronic HBV infection, serum HBV RNA levels vary. Serum HBV RNA can act as a biomarker to predict the natural history of disease in chronic hepatitis B patients. In treatment-naïve HBeAg-negative chronic HBV-infected individuals, serum HBV RNA shows superiority in differentiating the ‘HBeAg-negative reactive’ phase.

Background and Purpose Impaired protein homeostasis induced by endoplasmic reticulum (ER) dysfunction is a key feature of a variety of age-related brain diseases including stroke. To restore ER function impaired by stress, the unfolded protein response (UPR) is activated. A key UPR pro-survival pathway is controlled by the ER stress sensor inositol-requiring enzyme-1 (IRE1), downstream X-box binding protein-1 (XBP1), and O-linked b-N-acetylglucosamine (O-GlcNAc) modification of proteins (O-GlcNAcylation). Stroke impairs ER function, which activates UPR. The rationale of this study was to explore the potentials of the IRE1/XBP1/O-GlcNAc axis as a target for neuroprotection in ischemic stroke. Methods Mice with Xbp1 loss- and gain-of-function in neurons were generated. Stroke was induced by transient or permanent occlusion of the middle cerebral artery (MCAO) in young and aged mice. Thiamet-G was used to increase O-GlcNAcylation. Results Deletion of Xbp1 worsened outcome after transient and permanent MCAO. After stroke, O-GlcNAcylation was activated in neurons of the stroke penumbra in young mice, which was largely Xbp1-dependent. This activation of O-GlcNAcylation was impaired in aged mice. Pharmacologic increase of O-GlcNAcylation before or after stroke improved outcome in both young and aged mice. Conclusions Our study indicates a critical role for the IRE1/XBP1 UPR branch in stroke outcome. O-GlcNAcylation is a pro-survival pathway that is activated in the stroke penumbra in young mice but impaired in aged mice. Boosting pro-survival pathways to counterbalance the age-related decline in the brain’s self-healing capacity could be a promising strategy to improve ischemic stroke outcome in aged brains.