A new unconventional HLA-A2-restricted epitope from HBV core protein elicits antiviral cytotoxic T lymphocytes

Cytotoxic T cells (CTLs) play a key role in the control of Hepatitis B virus (HBV) infection and viral clearance. However, most of identified CTL epitopes are derived from HBV of genotypes A and D, and few have been defined in virus of genotypes B and C which are more prevalent in Asia. As HBV core protein (HBc) is the most conservative and immunogenic component, in this study we used an overlapping 9-mer peptide pool covering HBc to screen and identify specific CTL epitopes. An unconventional HLA-A2-restricted epitope HBc141–149 was discovered and structurally characterized by crystallization analysis. The immunogenicity and anti-HBV activity were further determined in HBV and HLA-A2 transgenic mice. Finally, we show that mutations in HBc141–149 epitope are associated with viral parameters and disease progression in HBV infected patients. Our data therefore provide insights into the structure characteristics of this unconventional epitope binding to MHC-I molecules, as well as epitope specific CTL activity that orchestrate T cell response and immune evasion in HBV infected patients

Differential gene expression for carotenoid biosynthesis in a green alga Ulva prolifera based on transcriptome analysis

Abstract Background Carotenoids are widely distributed in plants and algae, and their biosynthesis has attracted widespread interest. Carotenoid-related research has mostly focused on model species, and there is a lack of data on the carotenoid biosynthetic pathway in U. prolifera that is the main species leading to green tide, a harmful plague of floating green algae. Results The carotenoid content of U. prolifera samples, that is the main species leading to green tide, a harmful plague of floating green algae at different temperatures revealed that its terpenoid was highest in the samples subjected to high temperature at 28 °C (H), followed by the samples subjected to low temperature at 12 °C (L). Its terpenoid was lowest in the samples subjected to medium temperature at 20 °C (M). We conducted transcriptome sequencing (148.5 million raw reads and 49,676 unigenes in total) of samples that were subjected to different temperatures to study the carotenoid biosynthesis of U. prolifera. There were 1125–3164 significant differentially expressed genes between L, M and H incubation temperatures, of which 11–672 genes were upregulated and 453–3102 genes were downregulated. A total of 3164 genes were significantly differentially expressed between H and M, of which 62 genes were upregulated and 3102 genes were downregulated. A total of 2669 significant differentially expressed genes were observed between L and H, of which 11 genes were upregulated and 2658 genes were downregulated. A total of 13 genes were identified to be involved in carotenoid biosynthesis in U. prolifera, and the expression levels of the majority were highest at H and lowest at M of incubation temperature. Both the carotenoid concentrations and the expression of the analysed genes were lowest in the normal temperature group, while low temperature and high temperature seemed to activate the biosynthesis of carotenoids in U. prolifera. Conclusions In this study, transcriptome sequencing provided critical information for understanding the accumulation of carotenoids and will serve as an important reference for the study of other metabolic pathways in U. prolifera

The complete chloroplast genome of Chamaesium paradoxum

Chamaesium paradoxum H. Wolff is an endemic species naturally distributed in China. The complete chloroplast genome sequence of C. paradoxum was generated by de novo assembly using whole genome next generation sequencing data. The complete chloroplast genome of C. paradoxum is 153,512 bp in length, consisting of a pair of inverted repeats (IRs, 25,987 bp) separated by a large single-copy region (LSC, 84,162 bp) and a small single-copy region (SSC, 17,376 bp). There are 129 genes annotated, including 84 coding genes, 37 transfer RNA genes (tRNA), and eight ribosomal RNA genes (rRNA)

The complete chloroplast genome of Lilium Lankongense Franchet (Liliaceae)

The complete chloroplast genome sequence of Lilium lankongense Franchet is presented here. It is 152,611 bp in length and divides into four distinct regions: small single copy region of 17,506 bp, large single copy region of 81,995 bp, and a pair of inverted repeat regions (26,555 bp). The L. lankongense chloroplast genome annotation predicted a total of 131 genes, which contains 83 protein-coding genes, 38 transfer RNA genes, and 8 ribosomal RNA genes. In the maximum likelihood tree, all kinds of Lilium were clustered into two monophyletic groups

Increased expression of Gp96 by HBx-induced NF-κB activation feedback enhances hepatitis B virus production.

Elevated expression of heat shock protein gp96 in hepatitis B virus (HBV)-infected patients is positively correlated with the progress of HBV-induced diseases, but little is known regarding the molecular mechanism of virus-induced gp96 expression and its impact on HBV infection. In this study, up-regulation of gp96 by HBV replication was confirmed both in vitro and in vivo. Among HBV components, HBV x protein (HBx) was found to increase gp96 promoter activity and enhance gp96 expression by using a luciferase reporter system, and western blot analysis. Further, we found that HBx-mediated regulation of gp96 expression requires a NF-κB cis-regulatory element on the gp96 promoter, and chromatin immunoprecipitation results demonstrated that HBx promotes the binding of NF-κB to the gp96 promoter. Significantly, both gain- and loss-of-function studies showed that gp96 enhances HBV production in HBV-transfected cells and a mouse model based on hydrodynamic transfection. Moreover, up-regulated gp96 expression was observed in HBV-infected patients, and gp96 levels were correlated with serum viral loads. Thus, our work demonstrates a positive feedback regulatory pathway involving gp96 and HBV, which may contribute to persistent HBV infection. Our data also indicate that modulation of gp96 function may represent a novel strategy for the intervention of HBV infection

Gp96 promotes HBV production in mice.

<p>BALB/c mice were hydrodynamically co-injected with 5 µg pHBV and 1×10⁹ pfu adenovirus ad-gp96 (n = 5) or ad-CMV as a mock (n = 5). Three days later, the HBsAg and HBeAg levels in serum were measured by ELISA (A). HBV DNA levels in the serum (B) and liver (C) were determined by real-time PCR. HBcAg expression in the liver was examined by immunohistochemistry (D). *P<0.05 and **P<0.01 compared to the mock. Three independent experiments were performed with similar results.</p

Gp96 expression in the liver is correlated with viral loads and serum ALT/AST levels in CHB patients.

<p>(A) IHC detection of gp96 expression in healthy and CHB liver tissues. Representative images indicating immunostaining intensities of 0/1+, 2+, and 3+ are shown. Statistical analysis of gp96 expression by Pearson’s χ test is presented in the lower panel. (B) Distribution of serum HBV DNA loads in CHB patients with low, medium, and high gp96 expression in the liver. (C) Distribution of serum ALT and AST levels in CHB patients with low, medium, and high gp96 expression. Student’s t test was used to determine P-values.</p