Epidemiology and Mutational Analysis of Global Strains of Crimean-Congo Haemorrhagic Fever Virus

Crimean-Congo hemorrhagic fever (CCHF) is a severe illness with high fatality.Cases are reported in several countries in Africa,Europe,the Middle East,and Asia.Phylogenetic analyses based on the virus S (nucleocapsid),M (glycoprotein),and L (polymerase) genome segments sequences indicate distinct geographic lineages exist but their specific genetic characteristics require elucidation.In this work we collected all full length S segment sequences and generated a phylogenetic tree based on the alignment of these 62 samples.We then analyzed the alignment using entries from AAIndex,the Amino Acid Index database,to identify amino acid mutations that performed significant changes in charge,pka,hydropathy and side chain volume.Finally,we mapped these changes back to the tree and alignment to identify correlated mutations or sites that characterized a specific lineage.Based on this analysis we are able to propose a number of sites that appear to be important for virus function and which would be good candidates for experimental mutational analysis studies.     

Recombinant dengue virus type 3 envelope domain III protein from Escherichia coli

Dengue is a public health problem of global significance for which there is neither an effective antiviral therapy nor a preventive vaccine. The envelope protein of dengue virus is the major antigen to elicit neutralizing antibody response and protective immunity in hosts. Optimization of culture media was carried out for enhanced production of recombinant dengue virus type 3 envelope domain III (rDen 3 EDIII) protein in E. coli. Further, batch and fed-batch cultivation process were also developed in optimized medium. After fed-batch cultivation, the dry cell weight was about 22.80 g/L of culture. The rDen 3 EDIII protein was purified using immobilized metal affinity chromatography. This process produced ～649 mg of purified rDen 3 EDIII protein per liter of culture. The purity of the protein was determined by SDS-PAGE analysis and the reactivity was checked by Western blotting as well as ELISA. These results show that the purified protein may be used for the dengue diagnosis or further prophylactic studies for dengue infection.     

Mosquito vectors of the 1998-1999 outbreak of Rift Valley Fever and other arboviruses (Bagaza, Sanar, Wesselsbron and West Nile) in Mauritania and Senegal

Following an outbreak of Rift Valley fever (RVF) in south-eastern Mauritania during 1998, entomological investigations were conducted for 2 years in the affected parts of Senegal and Mauritania, spanning the Sénégal River basin. A total of 92 787 mosquitoes (Diptera: Culicidae), belonging to 10 genera and 41 species, were captured in light traps. In Senegal, Culex poicilipes (41%) and Mansonia uniformis (39%) were the most abundant species caught, whereas Aedes vexans (77%) and Cx. poicilipes (15%) predominated in Mauritania. RVF virus was isolated from 63 pools of Cx. poicilipes: 36 from Senegal in 1998 and 27 from Mauritania in 1999. These results are the first field evidence of Cx. poicilipes naturally infected with RVFV, and the first isolations of this virus from mosquitoes in Mauritania - the main West African epidemic and epizootic area. Additional arbovirus isolates comprised 25 strains of Bagaza (BAG) from Aedes fowleri, Culex neavei and Cx. poicilipes; 67 Sanar (ArD 66707) from Cx. poicilipes; 51 Wesselsbron (WSL) from Ae. vexans and 30 strains of West Nile (WN) from Ma. uniformis, showing differential specific virus-vector associations in the circulation activity of these five arboviruses.     

Proinflammatory factors present in sera from patients with acute dengue infection induce activation and apoptosis of human microvascular endothelial cells: possible role of TNF-alpha in endothelial cell damage in dengue

There is evidence that severe dengue disease is associated with alterations of the microvascular endothelium. We examined the hypothesis that activation and damage of microvascular endothelial cells (EC) could be induced by inflammatory mediators present in dengue patient's sera. We cultured human microvascular EC (HMEC-1) in vitro with sera from patients with acute dengue infection. Sera from patients with acute dengue induced an increase in ICAM-1 expression on HMEC-1. This effect was greater with samples from the acute febrile phase than with samples from the convalescent phase of the disease. Acute dengue sera had elevated levels of TNF-alpha and the endothelial activating effect of acute dengue sera was inhibited up to 80% by pre-treatment with monoclonal antibodies against TNF-alpha. Furthermore, acute dengue sera induced apoptosis in HMEC-1. These findings support the pathophysiologic significance of microvascular EC and serum inflammatory mediators in dengue.     

Review: Hyperthermia and fever during pregnancy

An episode of hyperthermia is not uncommon during pregnancy. The consequences depend on the extent of temperature elevation, its duration, and the stage of development when it occurs. Mild exposures during the preimplantation period and more severe exposures during embryonic and fetal development often result in prenatal death and abortion. Hyperthermia also causes a wide range of structural and functional defects. The central nervous system (CNS) is most at risk probably because it cannot compensate for the loss of prospective neurons by additional divisions by the surviving neuroblasts and it remains at risk at stages throughout pre- and postnatal life. In experimental animals the most common defects are of the neural tube, microphthalmia, cataract, and micrencephaly, with associated functional and behavioral problems. Defects of craniofacial development including clefts, the axial and appendicular skeleton, the body wall, teeth, and heart are also commonly found. Nearly all these defects have been found in human epidemiological studies following maternal fever or hyperthermia during pregnancy. Suggested future human studies include problems of CNS function after exposure to influenza and fever, including mental retardation, schizophrenia, autism, and cerebral palsy.     

Designing cyclic peptide inhibitor of dengue virus NS3-NS2B protease by using molecular docking approach

Peptides are preferred for designing inhibitors because of their high activity and specificity. Seven cyclopentapeptide inhibitors were designed in this study against dengue virus type 2 (DEN-2) NS3-NS2B protease: CKRRC, CGRRC, CRGRC, CRTRC, CTRRC, CKRKC and CRRKC. Docking analysis was performed to study the enzyme-inhibitor binding interactions. The free energy binding and estimated Ki values for all the inhibitors were found to be small (within micromolar range), indicating that the inhibitors bind considerably well to the binding site. The results showed that the cyclopentapeptide CKRKC was the best peptide inhibitor candidate with estimated free binding energy of -8.39 kcal/mol and Ki of 0.707 μM when compared to the standard inhibitor Bz-Nle-Lys-Arg-Arg-H that has been experimentally tested and shown to exhibit Ki value of 5.8 μM. Several modes of weak interactions were observed between the cyclopentapeptide CKRKC and the active site of DEN-2 NS3-NS2B protease. Thus, the cyclopentapeptide is proposed as a potential inhibitor to the NS3-NS2B protease activities of DEN-2. While these preliminary results are promising, further experimental investigation is necessary to validate the results.     

埃博拉出血热动物模型研究进展

埃博拉出血热是由埃博拉病毒引起的一种急性出血性传染病,具有极高的传染性,致死率高达50%～88%,目前对埃博拉出血热的预防还极为困难,暂无有效的抗病毒药物和疫苗。构建埃博拉出血热的动物模型,对于病毒致病机理的了解和深入研究,以及治疗药物及疫苗的研发具有至关重要的作用。     

Engineering the genomes of wild insect populations: Challenges, and opportunities provided by synthetic Medea selfish genetic elements

Advances in insect transgenesis and our knowledge of insect physiology and genomics are making it possible to create transgenic populations of beneficial or pest insects that express novel traits. There are contexts in which we may want the transgenes responsible for these traits to spread so that all individuals within a wild population carry them, a process known as population replacement. Transgenes of interest are unlikely to confer an overall fitness benefit on those who carry them. Therefore, an essential component of any population replacement strategy is the presence of a drive mechanism that will ensure the spread of linked transgenes. We discuss contexts in which population replacement might be desirable and the requirements a drive system must satisfy to be both effective and safe. We then describe the creation of synthetic Medea elements, the first selfish genetic elements synthesized de novo, with the capability of driving population replacement, in this case in Drosophila. The strategy used to create DrosophilaMedea is applicable to a number of other insect species and the Medea system satisfies key requirements for scientific and social acceptance. Finally, we highlight several challenges to implementing population replacement in the wild.     

Secondary heterologous dengue infection risk: Disequilibrium between immune regulation and inflammation?

Increased serum levels of cytokines released by cells of the immune response have been detected in patients suffering from dengue disease. Likewise, secondary infections by a different dengue virus serotype result in a highest risk of development of the severe dengue disease. Both findings suggest that the memory immune response is one of the key players in the pathogenesis of this disease. Here we take advantage of the particular Cuban epidemiological situation in dengue to analyze a broad spectrum of cell-mediated immune response mediators at mRNA and protein level. Evidences for a regulatory immune pattern in homologous (TGF-β, IL-10) vs. pro-inflammatory pattern (IFN-γ, TNF-α) in heterologous dengue virus re-challenge were found, suggesting a possible association with the higher incidence of severe dengue cases in the latter case.     

Epidemiology of relapsing fever borreliosis in Europe

Tick-borne relapsing fever is a bacterial infection caused by spirochetes of the genus Borrelia. This zoonotic disease is transmitted to humans through the bite of soft ticks of the genus Ornithodoros. It is responsible for recurring fever access associated with spirochetemia. We present here an overview of tick-borne relapsing fever occurring in Europe, as well as of the potential threat to travellers.