格特隐球菌基因组学研究进展

格特隐球菌属于新生隐球菌复合体,既往被认为是新生隐球菌复合体的变种,但最终被确立为独立的物种。与新生隐球菌不同,格特隐球菌多感染免疫力正常人群,目前致病机制尚未明确。格特隐球菌的基因组学研究不仅可全面了解其基因组成、分子进化、毒力因子以及致病机制等特点,还可对致病相关基因和重要蛋白进行预测,为疫苗和新型抗生素的研发提供分子基础,并进一步为高效治疗和防控隐球菌病提供理论依据。本文就格特隐球菌的基因组测序和基本特征、基因组进化、重要毒力基因以及比较基因组研究予以概述。

Role of dup A in virulence of Helicobacter pylori

Helicobacter pylori(H. pylori) is a gastric human pathogen associated with acute and chronic gastritis, 70% of all gastric ulcers, 85% of all duodenal ulcers, and both forms of stomach cancer, mucosal-associated lymphoid tissue(MALT) lymphoma and adenocarcinoma. Recently, attention has focused on possible relationship between presence of certain virulence factor and H. pylori-associated diseases. Some contradictory data between this bacterium and related disorders has been observed since not all the colonized individuals develop to severe disease. The reported diseases plausibility related to H. pylori specific virulence factors became an interesting story about this organism. Although a number of putative virulence factors have been identified including cytotoxin-associated gene a(cag A) and vac A, there are conflicting data about their actual participation as specific risk factor for H. pylori-related diseases. Duodenal ulcer promoting gene a(dup A) is a virulence factor of H. pylori that is highly associated with duodenal ulcer development and reduced risk of gastric cancer. The prevalence of dup A in H. pylori strains isolated from western countries is relatively higher than in H. pylori strains from Asian countries. Current confusing epidemiological reports will continue unless future sophisticated and molecular studies provide data on functional and complete dup A cluster in H. pylori infected individuals. This paper elucidates available knowledge concerning role of dup A in virulence of H. pylori after a decade of its discovery.

Cytomegalovirus enteritis mimicking Crohn's disease in a lupus nephritis patient:A case report

Cytomegalovirus(CMV)infection of the gastrointestinal (GI)tract has been reported in both immunocompetent and,more frequently,in immunocompromised patients.We describe a case of a 19-year-old male who developed CMV infection of the terminal ileum while receiving immunosuppression for lupus nephritis. This was a distinctly unusual site of infection which clinically mimicked Crohn's ileitis.We note that reports of terminal ileal CMV infection have been infrequent. Despite a complicated hospital course,ganciclovir therapy was effective in resolving his symptoms and normalizing his ileal mucosa.This report highlights the importance of accurate histological diagnosis and clinical follow-up of lupus patients with GI symptoms undergoing intense immunosuppression.

The Parasitoid Factor in the Virulence and Spread of Lepidopteran Baculoviruses

Insect parasitoids and baculoviruses play important roles in the natural and strategic biological control of insects. The two parasites are frequent competitors within common hosts and much research has focused on the negative impact that baculoviral host infections have on parasitoids. This review summarizes the impacts that parasitoids may have on the virulence and spread of lepidopteran baculoviruses. By changing host behavior and development, parasitoids have been shown to decrease baculovirus virulence and productivity within parasitized baculovirus-susceptible hosts; however, studies of the tools used by hymenopteran parasitoids to overcome their hosts'immune systems, suggest that parasitoids may, in some cases, facilitate baculoviral infections in less susceptible hosts. Laboratory and field research have demonstrated that parasitoids can mechanically transmit baculoviruses between insects, and in this way, increase the efficacy of the viruses. Instances of new, more virulent isolates of baculoviruses have been recorded from specifically parasitoid-targeted hosts suggesting other possible benefits from the transmission or activation of baculoviruses by parasitoids.

High affinity mouse-human chimeric Fab against Hepatitis B surface antigen

AIM： Passive immunotherapy using antibody against hepatitis B surface antigen （HBsAg） has been advocated in certain cases of Hepatitis B infection. We had earlier reported on the cloning and expression of a high affinity scFv derived from a mouse monoclonal （5S） against HBsAg. However this mouse antibody cannot be used for therapeutic purposes as it may elicit anti-mouse immune responses. Chimerization by replacing mouse constant domains with human ones can reduce the immunogenicity of this antibody.METHODS： We cloned the VH and V, genes of this mouse antibody, and fused them with CH1 domain of human IgG1 and C, domain of human kappa chain respectively. These chimeric genes were cloned into a phagemid vector. After initial screening using the phage display system, the chimeric Fab was expressed in soluble form in E. coli.RESULTS： The chimeric Fab was purified from the bacterial periplasmic extract. We characterized the chimeric Fab using several in vitro techniques and it was observed that the chimeric molecule retained the high affinity and specificity of the original mouse monoclonal. This chimeric antibody fragment was further expressed in different strains of E. coli to increase the yield.CONCLUSION： We have generated a mouse-human chimeric Fab against HBsAg without any significant loss in binding and epitope specificity. This chimeric Fab fragment can be further modified to generate a fulllength chimeric antibody for therapeutic uses.

Viral exploitation of actin: force-generation and scaffolding functions in viral infection

As a fundamental component of the host cellular cytoskeleton, actin is routinely engaged by infecting viruses. Furthermore, viruses from diverse groups, and infecting diverse hosts, have convergently evolved an array of mechanisms for manipulating the actin cytoskeleton for efficacious infection. An ongoing chorus of research now indicates that the actin cytoskeleton is critical for viral replication at many stages of the viral life cycle, including binding, entry, nuclear localization, genomic transcription and reverse transcription, assembly, and egress/dissemination. Specifically, viruses subvert the force-generating and macromolecular scaffolding properties of the actin cytoskeleton to propel viral surfing, internalization, and migration within the cell. Additionally, viruses utilize the actin cytoskeleton to support and organize assembly sites, and eject budding virions for cell-to-cell transmission. It is the purpose of this review to provide an overview of current research, focusing on the various mechanisms and themes of virus-mediated actin modulation described therein.

Short mucin 1 alleles are associated with low virulent H pylori strains infection

TO THE EDITORWe read with interest the article published by Nguyen et al in the World Journal of Gastroenterology, showing an association between short MUC6 alleles and H pjloff infection. These results, together with previous observations by Vinall et al, reinforce the role of mucin genes （MUC6 and MUC1） VNTR polymorphisms for the variability in individual susceptibility to H pylori infection that cannot be explained by differences in environmental factors.

An Overview of the Highly Pathogenic H5N1 Influenza Virus

Since the first human case of H5N1 avian influenza virus infection was reported in 1997, this highly pathogenic virus has infected hundreds of people around the world and resulted in many deaths. The ability of H5N1 to cross species boundaries, and the presence of polymorphisms that enhance virulence, present challenges to developing clear strategies to prevent the pandemic spread of this highly pathogenic avian influenza (HPAI) virus. This review summarizes the current understanding of, and recent research on, the avian influenza H5N1 virus, including transmission, virulence, pathogenesis, clinical characteristics, treatment and prevention.

Potency of Nannochloropsis oculata as Antibacterial, Antioxidant and Antiviral on Humpback Grouper Infected by Vibrio alginolyticus and Viral Nervous Necrotic

The aim of this study was to explore the potency of N. oculata extracts as antibacterial, antioxidant and antiviral on grouper Cromileptes altivelis （C. altivelis） infected by Vibrio alginolyticus （V. alginolyticus） and Viral Nervous Necrotic （VNN）. Dilution test was used to measure antibacterial activity of N. oculata extracts. Antioxidant activity of extracts was expressed by levels of MDA （Malondialdehyde） and SOD （superoxide dismutase） in the brain and kidneys of fish. Antiviral capability of N. oculata was determined by the expression of cellular immune cells Major Histocompatibility Complex （MHC） Class I for proliferation and inhibition of VNN in blood cells with immunocytochemistry. The results showed that N. oculata extract was able to suppress the growth of V. alginolyticus at a concentration of 40%. Increasing levels of SOD and reducing level of MDA indicated that N. oculata extracts may serve as an antibacterial and antioxidant. Providing cellular response of MHC class I cell expressed on C. altive/is blood cells, N. oculata demonstrated its antiviral activity.

Stress Granule Formation is One of the Early Antiviral Mechanisms for Host Cells Against Coxsackievirus B Infection

Stress granules(SGs) are intracellular granules formed when cellular translation is blocked and have been reported to be involved in a variety of viral infections. Our previous studies revealed that SGs are involved in the coxsackievirus B(CVB)infection process, but the role of SGs in CVB infection has not been fully explored. In this study, we found that CVB type 3(CVB3) could induce SG formation in the early phase of infection. Results showed that levels of CVB3 RNA and protein were significantly inhibited during the early stage of CVB3 infection by the elevated formation of SGs, while viral RNA and protein synthesis were significantly promoted when SG formation was blocked. Our findings suggest that SG formation is one of the early antiviral mechanisms for host cells against CVB infection.

Effects of combined drug therapy on HIV-1 infection dynamics

Infection of human immunodeficiency virus （HIV） is determined through the decay of healthy CD44- T-cells in a well-mixed compartment, such as a bloodstream. A mathe- matical model is considered to illustrate the effects of combined drug therapy, i.e. reverse transcription plus protease inhibitor, on viral growth and T-cell population dynamics. This model is used to explain the existence and stability of infected and uninfected steady states in HIV growth. An analytical technique, called variational iteration method （VIM）, is used to solve the mathematical model. This method is modified to obtain the rapidly convergent successive approximations of the exact solution. These approximations are obtained without any restrictions or the transformations that may change the physical behavior of the problem. Numerical simulations are computed and exhibited to illustrate the effects of proposed drug therapy on the growth or decay of infection.

Global dynamics of hepatitis C viral infection with logistic proliferation

A modified mathematical model of hepatitis C viral dynamics has been presented in this paper, which is described by four coupled ordinary differential equations. The aim of this paper is to perform global stability analysis using geometric approach to stability, based on the higher-order generalization of Bendixson＇s criterion. The result is also supported numerically. An important epidemiological issue of eradicating hepatitis C virus has been addressed through the global stability analysis.

Dynamics of an infection model with two delays

In this paper, a HTLV-I infection model with two delays is considered. It is found that the dynamics of this model are determined by two threshold parameters R0 and R1, basic reproduction numbers for viral infection and for CTL response, respectively. If R0 〈 1, the infection-free equilibrium P0 is globally asymptotically stable. If R1 〈 1 〈 R0, the asymptomatic-carrier equilibrium P1 is globally asymptotically stable. If R1 〉 1, there exists a unique HAM/TSP equilibrium P2. The stability of P2 is changed when the second delay T2 varies, that is there exist stability switches for P2.