A Combination of Doxycycline and Ribavirin Alleviated Chikungunya Infection

Lack of vaccine and effective antiviral drugs against chikungunya virus (CHIKV) outbreaks have led to significant impact on health care in the developing world. Here, we evaluated the antiviral effects of tetracycline (TETRA) derivatives and other common antiviral agents against CHIKV. Our results showed that within the TETRA derivatives group, Doxycycline (DOXY) exhibited the highest inhibitory effect against CHIKV replication in Vero cells. On the other hand, in the antiviral group Ribavirin (RIBA) showed higher inhibitory effects against CHIKV replication compared to Aciclovir (ACIC). Interestingly, RIBA inhibitory effects were also higher than all but DOXY within the TETRA derivatives group. Docking studies of DOXY to viral cysteine protease and E2 envelope protein showed non-competitive interaction with docking energy of -6.6±0.1 and -6.4±0.1 kcal/mol respectively. The 50% effective concentration (EC50) of DOXY and RIBA was determined to be 10.95±2.12 μM and 15.51±1.62 μM respectively, while DOXY+RIBA (1:1 combination) showed an EC₅₀ of 4.52±1.42 μM. When compared, DOXY showed higher inhibition of viral infectivity and entry than RIBA. In contrast however, RIBA showed higher inhibition against viral replication in target cells compared to DOXY. Assays using mice as animal models revealed that DOXY+RIBA effectively inhibited CHIKV replication and attenuated its infectivity in vivo. Further experimental and clinical studies are warranted to investigate their potential application for clinical intervention of CHIKV disease.     

Differential Proteome Analysis of Chikungunya Virus Infection on Host Cells

Background

Chikungunya virus (CHIKV) is an emerging mosquito-borne alphavirus that has caused multiple unprecedented and re-emerging outbreaks in both tropical and temperate countries. Despite ongoing research efforts, the underlying factors involved in facilitating CHIKV replication during early infection remains ill-characterized. The present study serves to identify host proteins modulated in response to early CHIKV infection using a proteomics approach.

Methodology and Principal Findings

The whole cell proteome profiles of CHIKV-infected and mock control WRL-68 cells were compared and analyzed using two-dimensional gel electrophoresis (2-DGE). Fifty-three spots were found to be differentially modulated and 50 were successfully identified by MALDI-TOF/TOF. Eight were significantly up-regulated and 42 were down-regulated. The mRNA expressions of 15 genes were also found to correlate with the corresponding protein expression. STRING network analysis identified several biological processes to be affected, including mRNA processing, translation, energy production and cellular metabolism, ubiquitin-proteasome pathway (UPP) and cell cycle regulation.

Conclusion/Significance

This study constitutes a first attempt to investigate alteration of the host cellular proteome during early CHIKV infection. Our proteomics data showed that during early infection, CHIKV affected the expression of proteins that are involved in mRNA processing, host metabolic machinery, UPP, and cyclin-dependent kinase 1 (CDK1) regulation (in favour of virus survival, replication and transmission). While results from this study complement the proteomics results obtained from previous late host response studies, functional characterization of these proteins is warranted to reinforce our understanding of their roles during early CHIKV infection in humans.     

Development of a Hamster Model for Chikungunya Virus Infection and Pathogenesis

Chikungunya virus is transmitted by mosquitoes and causes severe, debilitating infectious arthritis in humans. The need for an animal model to study the disease process and evaluate potential treatments is imminent as the virus continues its spread into novel geographic locations. Golden hamsters (Mesocricetus auratus) are often used as outbred laboratory animal models for arboviral diseases. Here we demonstrate that hamsters inoculated with chikungunya virus developed viremia and histopathologic lesions in their limbs and joints similar to those seen in human patients. The virus disseminated rapidly and was found in every major organ, including brain, within a few days of infection. Hamsters did not manifest overt clinical signs, and the virus was generally cleared within 4 days, followed by a strong neutralizing antibody response. These results indicate that hamsters are highly susceptible to chikungunya virus infection and develop myositis and tenosynovitis similar to human patients followed by a complete recovery. This animal model may be useful for testing antiviral drugs and vaccines.     

Chikungunya Virus Infection of Cell Monolayers by Cell-to-Cell and Extracellular Transmission

Both cell-to-cell and extracellular transmission of chikungunya virus infection was demonstrated in BHK21/C13 cell monolayers. The mode of virus infection may depend on the cell line. Virus transmission in L-929 and guinea pig lung cell lines was extracellular.     

Utilization of an Eilat Virus-Based Chimera for Serological Detection of Chikungunya Infection

In December of 2013, chikungunya virus (CHIKV), an alphavirus in the family Togaviridae, was introduced to the island of Saint Martin in the Caribbean, resulting in the first autochthonous cases reported in the Americas. As of January 2015, local and imported CHIKV has been reported in 50 American countries with over 1.1 million suspected cases. CHIKV causes a severe arthralgic disease for which there are no approved vaccines or therapeutics. Furthermore, the lack of a commercially available, sensitive, and affordable diagnostic assay limits surveillance and control efforts. To address this issue, we utilized an insect-specific alphavirus, Eilat virus (EILV), to develop a diagnostic antigen that does not require biosafety containment facilities to produce. We demonstrated that EILV/CHIKV replicates to high titers in insect cells and can be applied directly in enzyme-linked immunosorbent assays without inactivation, resulting in highly sensitive detection of recent and past CHIKV infection, and outperforming traditional antigen preparations.     

Native Wolbachia from Aedes albopictus Blocks Chikungunya Virus Infection In Cellulo

Wolbachia, a widespread endosymbiont of terrestrial arthropods, can protect its host against viral and parasitic infections, a phenotype called "pathogen blocking". However, in some cases Wolbachia may have no effect or even enhance pathogen infection, depending on the host-Wolbachia-pathogen combination. The tiger mosquito Aedes albopictus is naturally infected by two strains of Wolbachia, wAlbA and wAlbB, and is a competent vector for different arboviruses such as dengue virus (DENV) and Chikungunya virus (CHIKV). Interestingly, it was shown in some cases that Ae. albopictus native Wolbachia strains are able to inhibit DENV transmission by limiting viral replication in salivary glands, but no such impact was measured on CHIKV replication in vivo. To better understand the Wolbachia/CHIKV/Ae. albopictus interaction, we generated a cellular model using Ae. albopictus derived C6/36 cells that we infected with the wAlbB strain. Our results indicate that CHIKV infection is negatively impacted at both RNA replication and virus assembly/secretion steps in presence of wAlbB. Using FISH, we observed CHIKV and wAlbB in the same mosquito cells, indicating that the virus is still able to enter the cell in the presence of the bacterium. Further work is needed to decipher molecular pathways involved in Wolbachia-CHIKV interaction at the cellular level, but this cellular model can be a useful tool to study the mechanism behind virus blocking phenotype induced by Wolbachia. More broadly, this underlines that despite Wolbachia antiviral potential other complex interactions occur in vivo to determine mosquito vector competence in Ae. albopictus.     

Transformation During Mixed Pneumococcal Infection of Mice

The recent demonstration by others of transformation during peritoneal infection of mice by two genetically distinct pneumococcal strains supports the notion that transformation may be significant in pneumococcal infection in nature. These studies confirm the occurrence of transformation during mixed infection of mice and define some conditions for its occurrence and its significance. Mice were inoculated with deoxyribonucleic acid (DNA) donor (small type III capsule, low virulence, streptomycin-susceptible) and recipient (noncapsulated, low virulence, streptomycin-resistant) pneumococci, and the bacteremia in mice that died was evaluated. Transformants (large type III capsule, virulent, streptomycin-resistant) were isolated from up to 80% of mice that died from mixed peritoneal infection. Transformation occurred in mice that received donor and recipient 6 hr apart; hence, active DNA was released and competence developed during growth in vivo. Transformation was detected only with progressive infection by both strains, and then transformants were few in the blood and apparently were not responsible for the death of the animals. In doubly infected mice treated with streptomycin, transformation was enhanced; transformants numerically dominated the bacteremia and seemed to cause the death of the mice. Transformation was also demonstrated for the first time during infection of the respiratory tract.     

Cross-Inhibition of Chikungunya Virus Fusion and Infection by Alphavirus E1 Domain III Proteins

Alphaviruses are small enveloped RNA viruses that include important emerging human pathogens, such as chikungunya virus (CHIKV). These viruses infect cells via a low-pH-triggered membrane fusion reaction, making this step a potential target for antiviral therapies. The E1 fusion protein inserts into the target membrane, trimerizes, and refolds to a hairpin-like conformation in which the combination of E1 domain III (DIII) and the stem region (DIII-stem) pack against a core trimer composed of E1 domains I and II (DI/II). Addition of exogenous DIII proteins from Semliki Forest virus (SFV) has been shown to inhibit E1 hairpin formation and SFV fusion and infection. Here we produced and characterized DIII and DI/II proteins from CHIKV and SFV. Unlike SFV DIII, both core trimer binding and fusion inhibition by CHIKV DIII required the stem region. CHIKV DIII-stem and SFV DIII-stem showed efficient cross-inhibition of SFV, Sindbis virus, and CHIKV infections. We developed a fluorescence anisotropy-based assay for the binding of SFV DIII-stem to the core trimer and used it to demonstrate the relatively high affinity of this interaction (K_d [dissociation constant], ∼85 nM) and the importance of the stem region. Together, our results support the conserved nature of the key contacts of DIII-stem in the alphavirus E1 homotrimer and describe a sensitive and quantitative in vitro assay for this step in fusion protein refolding.     

基孔肯雅热

基孔肯雅热(Chikungunya fever,CHIK)是由基孔肯雅病毒(Chikungunya virus,CHIKV)病毒引起的,伊蚊叮咬传播的,以发热、关节疼痛等为主要特征的自限性传染性疾病。1952年在坦桑尼亚发生的暴发流行中首次分离CHIKV[1-2],亚洲地区于     

Impact of Wolbachia on Infection with Chikungunya and Yellow Fever Viruses in the Mosquito Vector Aedes aegypti

Incidence of disease due to dengue (DENV), chikungunya (CHIKV) and yellow fever (YFV) viruses is increasing in many parts of the world. The viruses are primarily transmitted by Aedes aegypti, a highly domesticated mosquito species that is notoriously difficult to control. When transinfected into Ae. aegypti, the intracellular bacterium Wolbachia has recently been shown to inhibit replication of DENVs, CHIKV, malaria parasites and filarial nematodes, providing a potentially powerful biocontrol strategy for human pathogens. Because the extent of pathogen reduction can be influenced by the strain of bacterium, we examined whether the wMel strain of Wolbachia influenced CHIKV and YFV infection in Ae. aegypti. Following exposure to viremic blood meals, CHIKV infection and dissemination rates were significantly reduced in mosquitoes with the wMel strain of Wolbachia compared to Wolbachia-uninfected controls. However, similar rates of infection and dissemination were observed in wMel infected and non-infected Ae. aegypti when intrathoracic inoculation was used to deliver virus. YFV infection, dissemination and replication were similar in wMel-infected and control mosquitoes following intrathoracic inoculations. In contrast, mosquitoes with the wMelPop strain of Wolbachia showed at least a 10⁴ times reduction in YFV RNA copies compared to controls. The extent of reduction in virus infection depended on Wolbachia strain, titer and strain of the virus, and mode of exposure. Although originally proposed for dengue biocontrol, our results indicate a Wolbachia-based strategy also holds considerable promise for YFV and CHIKV suppression.     

基孔肯亚假病毒模型的建立及其在模拟检测中的应用

目的:构建含基孔肯亚病毒核酸序列的重组慢病毒载体,以之转染细胞以分泌含基孔肯亚病毒核酸序列的假病毒,利用该病毒建立基孔肯亚病毒的模拟检测方法。方法:人工合成基孔肯亚病毒部分保守性核酸序列,连入慢病毒载体,构建含基孔肯亚病毒核酸序列的重组慢病毒质粒pLenti-chik,该质粒连同辅助质粒pLP1、pLP2、pLP/VSVG共转染293FT细胞;72 h后收集上清,用特异引物进行荧光定量RT-PCR检测。结果:建立了一个仅能进行一次复制、高度安全的基孔肯亚假病毒模型;同时采用荧光定量RT-PCR建立了较灵敏的检测病毒分泌的方法。结论:假病毒可以模拟基孔肯亚病毒分泌,但较真病毒安全性更高;用荧光定量的方法可以很灵敏地检测病毒的分泌,为突发基孔肯亚病毒感染的检测做好准备。     

Mixed Infection and the Genesis of Influenza Virus Diversity

The emergence of viral infections with potentially devastating consequences for human health is highly dependent on their underlying evolutionary dynamics. One likely scenario for an avian influenza virus, such as A/H5N1, to evolve to one capable of human-to-human transmission is through the acquisition of genetic material from the A/H1N1 or A/H3N2 subtypes already circulating in human populations. This would require that viruses of both subtypes coinfect the same cells, generating a mixed infection, and then reassort. Determining the nature and frequency of mixed infection with influenza virus is therefore central to understanding the emergence of pandemic, antigenic, and drug-resistant strains. To better understand the potential for such events, we explored patterns of intrahost genetic diversity in recently circulating strains of human influenza virus. By analyzing multiple viral genome sequences sampled from individual influenza patients we reveal a high level of mixed infection, including diverse lineages of the same influenza virus subtype, drug-resistant and -sensitive strains, those that are likely to differ in antigenicity, and even viruses of different influenza virus types (A and B). These results reveal that individuals can harbor influenza viruses that differ in major phenotypic properties, including those that are antigenically distinct and those that differ in their sensitivity to antiviral agents.Influenza viruses (family Orthomyxoviridae) possess a negative-strand segmented RNA genome and enveloped virions. Genetic diversity in influenza virus is the result of a high rate of mutation associated with replication using low-fidelity RNA polymerase and of the reshuffling (or reassortment) of segments among coinfecting strains. Although the 13.5-kb genome of influenza A virus is composed of eight segments coding for 11 known proteins, these viruses are typically categorized by their two surface antigens, hemagglutinin (HA), of which there are 16 subtypes (H1 to H16), and neuraminidase (NA), of which there are 9 (N1 to N9) (9). All known subtypes are present in aquatic birds of the orders Anseriformes and Charadriformes, and a smaller number circulate in some mammalian species. The HA plays a major role in the attachment of the virus to the host cell surface by binding to the sialic acid moiety of host receptors and facilitating the fusion of the viral envelope with host cell membranes. It is also the major viral antigen against which neutralizing antibodies are directed. The NA is important for mobility of the virions by cleaving the sialic acid residues from the viral hemagglutinin, which facilitates both entry of the virus into the cell and release of the viruses during budding (11).Most discussions of influenza virus evolution have focused on the process of antigenic drift in which mutations accumulate—most likely by natural selection—in the antigenic sites of the HA and NA, thereby allowing evasion of the host populations’ acquired immunity to previously circulating strains. Such antigenic variation occurs primarily in the HA1 domain and is clustered into five main epitope regions (19, 20, 22). Although antigenic drift clearly plays a key role in the seasonal evolution of influenza A virus, recent studies making use of large data sets generated by the Influenza Genome Sequencing Project (IGSP) suggest that reassortment may also be important in the generation of antigenically novel isolates by placing diverse HAs in compatible genetic backgrounds (6, 8, 10, 14).Segment reassortment is also central to the process of cross-species transmission and emergence of pandemic influenza virus. In particular, the segmented nature of the influenza virus genome allows reassortment of gene segments to occur between diverse influenza A virus strains when they coinfect a single host, including those derived from different species. This can result in subtle changes within a subtype, or dramatic changes that occur when different subtypes mix, leading to the generation of novel viruses expressing surface glycoproteins to which a specific host immune system has little if any serological cross-reactivity. Such antigenic shift is believed to have led to the emergence of global human influenza A virus pandemics in 1957 (A/H2N2) and in 1968 (A/H3N2), with new segments ultimately derived from the avian reservoir pool reassorting into human influenza viruses (17).Given the potential for emerging viruses such as influenza virus to adversely affect the health of human and other animal populations, it is essential to determine the factors that allow viruses to acquire the mutations they need to adapt to new host populations. As a large number of point mutations are thought to be required for an avian influenza virus such as A/H5N1 to evolve sustained transmission in human populations (5), one likely scenario for successful emergence is through the acquisition of genetic material from a viral subtype already adapted to humans, such as A/H1N1 or A/H3N2. This would require that viruses of both subtypes coinfect the same cells, thereby generating a mixed infection, and then exchange genomic segments through reassortment, as was the case in 1957 and 1968. As a consequence, it is crucial to determine the frequency with which mixed infection naturally occurs in influenza A virus as well as its phenotypic consequences. To address these questions we undertook, for the first time, in-depth sequencing of multiple viral genome sequences sampled from individual influenza patients. These studies were performed with approval of the New York State (study numbers 04-103 and 02-054) and University of Pittsburgh (08-110400) institutional review boards.