Three-Dimensional Reconstruction of the Hepatitis C Virus Envelope Glycoprotein E1E2 Heterodimer by Electron Microscopic Analysis.

Despite the development of highly effective hepatitis C virus (HCV) treatments, an effective prophylactic vaccine is still lacking. HCV infection is mediated by its envelope glycoproteins, E1 and E2, during the entry process, with E2 binding to cell receptors and E1 mediating endosomal fusion. The structure of E1E2 has only been partially resolved by X-ray crystallography of the core domain of E2 protein (E2c) and its complex with various neutralizing antibodies. Structural understanding of the E1E2 heterodimer in its native form can advance the design of candidates for HCV vaccine development. Here, we analyze the structure of the recombinant HCV E1E2 heterodimer with the aid of well-defined monoclonal anti-E1 and E2 antibodies, as well as a small-molecule chlorcyclizine-diazirine-biotin that can target and cross-link the putative E1 fusion domain. Three-dimensional (3D) models were generated after extensive 2D classification analysis with negative-stain single-particle data sets. We modeled the available crystal structures of the E2c and Fabs into 3D volumes of E1E2-Fab complexes based on the shape and dimension of the domain density. The E1E2 heterodimer exists in monomeric form and consists of a main globular body, presumably depicting the E1 and E2 stem/transmembrane domain, and a protruding structure representing the E2c region, based on anti-E2 Fab binding. At low resolution, a model generated from negative-stain analysis revealed the unique binding and orientation of individual or double Fabs onto the E1 and E2 components of the complex. Cryo-electron microscopy (cryo-EM) of the double Fab complexes resulted in a refined structural model of the E1E2 heterodimer, presented here. IMPORTANCE Recombinant HCV E1E2 heterodimer is being developed as a vaccine candidate. Using electron microscopy, we demonstrated unique features of E1E2 in complex with various neutralizing antibodies and small molecule inhibitors that are important to understanding its antigenicity and induction of immune response.

Chronic Administration of Diethylnitrosamine and 2-Acetylaminofluorene Induces Hepatocellular Carcinoma in Wistar Rats.

This study aimed to analyze the biochemical, histological, and gene expression alterations produced in a hepatocarcinogenesis model induced by the chronic administration of diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF) in Wistar rats. Thirteen rats weighing 180 to 200 g were divided into two groups: control and treated. Rats in the treated group were administered an intraperitoneal (i.p.) injection of DEN (50 mg/kg/week) and an intragastric (i.g.) dose of 2-AAF (25 mg/kg/week) for 18 weeks. The treated group had significant increases in their total cholesterol, HDL-C, AST, ALT, ALKP, and GGT levels. Furthermore, a histological analysis showed the loss of normal liver architecture with nuclear pleomorphism in the hepatocytes, atypical mitosis, and fibrous septa that were distributed between the portal triads and collagen fibers through the hepatic sinusoids. The gene expressions of 24 genes related to fibrosis, inflammation, apoptosis, cell growth, angiogenesis, lipid metabolism, and alpha-fetoprotein (AFP) were analyzed; only TGFß, COL1α1, CYP2E1, CAT, SOD, IL6, TNF-α, and ALB showed significant differences when both groups were compared. Additionally, lung histopathological alterations were found in the treated group, suggesting metastasis. In this model, the chronic administration of DEN+2-AAF induces characteristic alterations of hepatocellular carcinoma in Wistar rats without AFP gene expression changes, highlighting different signatures in hepatocellular carcinoma heterogeneity.

High frequency of the risk allele of rs4132601 and rs11978267 from the IKZF1 gene in indigenous Mexican population.

BACKGROUND: IKZF1 is a relevant gene associated with the pathogenesis of acute lymphoblastic leukemia, and the rs4132601 (T>G) and rs11978267 (A>G) polymorphisms have been associated with the development of this disease in several populations. The aim of this study was to determine the allelic and genotypic frequencies of the rs4132601 and rs11978267 polymorphisms in two indigenous Mexican groups (Cora and Huichol) and Mestizo populations from Nayarit, Mexico, and compare them with the frequencies of both polymorphisms in other populations of the world. METHODS: One hundred, 116, and 100 subjects from the Mestizo, Huichol, and Cora populations, respectively, all of them residents of the state of Nayarit, Mexico, were analyzed. The frequencies of rs4132601 and rs11978267 were determined by allelic discrimination using TaqMan assays. RESULTS: The allelic frequencies of rs4132601 were as follows: Mestizo group T = 0.74, G = 0.26; Cora T = 0.745, G = 0.255; and Huichol T = 0.47, G = 0.53. In the case of the rs11978267 polymorphism, the allelic frequencies were Mestizo A = 0.745, G = 0.255; Cora A = 0.735, G = 0.265; and Huichol A = 0.457, G = 0.543. For each population, both polymorphisms were in Hardy-Weinberg equilibrium. CONCLUSION: The Huichol population from Nayarit presented the highest frequencies of the risk allele reported to date in the whole world for both rs4132601 and rs11978267 polymorphisms.