Human rhinovirus species C (HRV-C) was recently discovered using molecular diagnostic techniques and is associated with lower respiratory tract disease, particularly in children. HRV-C cannot be propagated in immortalized cell lines, and currently sinus organ culture is the only system described that is permissive to HRV-C infection ex vivo. However, the utility of organ culture for studying HRV-C biology is limited. Here, we report that a previously described HRV-C derived from an infectious cDNA, HRV-C15, infects and propagates in fully differentiated human airway epithelial cells but not in undifferentiated cells. We demonstrate that this differentiated epithelial cell culture system supports infection and replication of a second virus generated from a cDNA clone, HRV-C11. We show that HRV-C15 virions preferentially bind fully differentiated airway epithelial cells, suggesting that the block to replication in undifferentiated cells is at the step of viral entry. Consistent with previous reports, HRV-C15 utilizes a cellular receptor other than ICAM-1 or LDLR for infection of differentiated epithelial cells. Furthermore, we demonstrate that HRV-C15 replication can be inhibited by an HRV 3C protease inhibitor (rupintrivir) but not an HRV capsid inhibitor previously under clinical development (pleconaril). The HRV-C cell culture system described here provides a powerful tool for studying the biology of HRV-C and the discovery and development of HRV-C inhibitors.

Dihydroartemisinin (DHA) is an important derivative of an herb medicine Artemisia annua L., used in ancient China. DHA is currently used world-wide to treat malaria by killing malaria-causing parasites. In addition to this prominent effect, DHA is suggested to regulate cellular functions, such as angiogenesis, tumor cell growth and immunity. Nonetheless, how DHA affects T cell function remains poorly understood. We found that DHA potently suppressed Th cell differentiation in vitro. Unexpectedly however, DHA greatly promoted Treg cell generation, in a manner dependent on TGF-βR:Smad signal. In addition, DHA treatment effectively reduced EAE onset and ameliorated ongoing EAE in mice. Administration of DHA significantly decreased Th but increased Treg cells in EAE-inflicted mice without apparent global immune suppression. Moreover, DHA modulated mTOR pathway, because mTOR signal was attenuated in T cells upon DHA treatment. Importantly, enhanced Akt activity neutralized DHA-mediated effects on T cells in an mTOR dependent fashion. This study therefore reveals a novel immune regulatory function of DHA to reciprocally regulate Th and Treg cell generation through modulating mTOR pathway. It addresses how DHA regulates immune function and suggests a new type of drug for treating diseases where mTOR activity to be tempered.

Human rhinoviruses (HRV) cause the majority of common colds and acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Effective therapies are urgently needed, but no licensed treatments or vaccines currently exist. Of the 100 identified serotypes, ∼90% bind domain 1 of human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor, making this an attractive target for development of therapies; however, ICAM-1 domain 1 is also required for host defence and regulation of cell trafficking, principally via its major ligand LFA-1. Using a mouse anti-human ICAM-1 antibody (14C11) that specifically binds domain 1 of human ICAM-1, we show that 14C11 administered topically or systemically prevented entry of two major groups of rhinoviruses, HRV16 and HRV14, and reduced cellular inflammation, pro-inflammatory cytokine induction and virus load in vivo. 14C11 also reduced cellular inflammation and Th2 cytokine/chemokine production in a model of major group HRV-induced asthma exacerbation. Interestingly, 14C11 did not prevent cell adhesion via human ICAM-1/LFA-1 interactions in vitro, suggesting the epitope targeted by 14C11 was specific for viral entry. Thus a human ICAM-1 domain-1-specific antibody can prevent major group HRV entry and induction of airway inflammation in vivo.

While nonstructural protein 4B (NS4B) from hepatitis C virus (HCV) is absolutely required for viral propagation, a full understanding of the enzymatic properties of this protein is lacking. Previous studies suggest that NS4B is located at the endoplasmic reticulum and that the protein structure consists of four central transmembrane domains with the N- and C-termini located in the cytoplasm of the host cell. To characterize the enzymatic activity of NS4B, the full-length protein with a C-terminal His tag was expressed in Sf9 insect cells and stabilized with nonionic detergents during purification. Chemical cross-linking experiments using GTP-gamma-azidoanilide and ATP-gamma-azidoanilide and equilibrium binding analyses with GTPgammaS and ATPgammaS show that both GTP and ATP are bound by NS4B, with ATP displaying a higher affinity. Analyses of enzymatic reactions catalyzed by NS4B indicate that the terminal phosphate groups of ATP, GTP, and GDP are removed to produce ADP, GDP, and GMP, respectively. The k(cat) for hydrolysis of GTP by purified NS4B compared favorably with the k(cat) for hydrolysis of GTP by Ras-p21 in the absence of GTPase activating proteins (GAPs). In addition to the hydrolysis of NTP and NDP substrates, adenylate kinase activity was detected in purified preparations of NS4B with the reverse reaction 2ADP --> ATP + ADP, yielding a larger k(cat) compared to that of the forward reaction ATP + AMP --> 2ADP. These studies suggest that HCV NS4B possesses both adenylate kinase activity and nucleotide hydrolase activity. Mutation of amino acids in the Walker A and B motifs of NS4B resulted in decreased affinity for both GTPgammaS and ATPgammaS as well as decreased ATP hydrolysis and AK activity.

Functional brain imaging has tremendous applications. The existing methods for functional brain imaging include functional Magnetic Resonant Imaging (fMRI), scalp electroencephalography (EEG), implanted EEG, magnetoencephalography (MEG) and Positron Emission Tomography (PET), which have been widely and successfully applied to various brain imaging studies. To develop a new method for functional brain imaging, here we show that the dielectric at a brain functional site has a dynamic nature, varying with local neuronal activation as the permittivity of the dielectric varies with the ion concentration of the extracellular fluid surrounding neurons in activation. Therefore, the neuronal activation can be sensed by a radiofrequency (RF) electromagnetic (EM) wave propagating through the site as the phase change of the EM wave varies with the permittivity. Such a dynamic nature of the dielectric at a brain functional site provides the basis for an RF EM wave approach to detecting and imaging neuronal activation at brain functional sites, leading to an RF EM wave approach to functional brain imaging.

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Hepatitis C virus (HCV) research and drug discovery have been facilitated by the introduction of cell lines with self-replicating subgenomic HCV replicons. Early attempts to carry out robust, high-throughput screens (HTS) using HCV replicons have met with limited success. Specifically, selectable replicons have required laborious reverse transcription-PCR quantitation, and reporter replicons have generated low signal-to-noise ratios. In this study, we constructed a dicistronic single reporter (DSR)-selectable HCV replicon that contained a humanized Renilla luciferase (hRLuc) gene separated from the selectable Neo r marker by a short peptide cleavage site. The mutations E1202G, T1280I, and S2197P were introduced to enhance replicative capability. Approximately 170 million people globally test positive for hepatitis C virus (HCV) (9, 11). Infection by HCV results in a high degree of chronic hepatitis. In addition to inducing liver damage, a significant proportion of these infections also result in hepatocellular carcinoma. Although current treatments for hepatitis caused by HCV include interferon in combination with ribavirin (18), approximately 50 to 60% of individuals still are not able to resolve infection (15). Therefore, there is an unmet medical need to develop more effective therapies to treat HCV infection. Until 1999, all cell-based screening efforts for HCV drug discovery relied on surrogate viral systems, such as bovine viral diarrhea virus, and the potential development of assays where activities of specific viral targets could be monitored. In 1999, a significant breakthrough in studying HCV RNA replication occurred when the Bartenschlager laboratory developed the HCV replicon system, a tissue culture system that faithfully mimicked all of the RNA replication events of the HCV life cycle (21). This initiated a phase of intensified research into the mechanisms of HCV RNA translation, replication, and protein processing. It also ushered in a new era for HCV drug discovery, since it was now possible to test the effects of inhibitors of traditional targets, such as NS3 protease, helicase, and NS5B polymerase, in an authentic, in vitro HCV RNA replication system (1).The original replicon system (21) was constructed by replacement of genes from the HCV genome that are not essential for HCV RNA replication, e.g., the structural genes, p7 and NS2, with a genetic cassette carrying an antibiotic resistance gene and the internal ribosomal entry site (IRES) from encephalomyocarditis virus (EMCV). This resulted in the formation of a dicistronic, selectable, subgenomic HCV replicon (2-4, 21) whose replication requires RNA elements in both nontranslated regions as well as the nonstructural proteins, including NS3 protease, helicase, and polymerase. Therefore, the HCV replicon system can be used for identifying inhibitors against all of these components (1).Cell-based screening efforts in a high-throughput format to identify novel inhibitors and viral or host targets have recently been described (6,23,34). The first ...

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