Climate change influences on global distributions of dengue and chikungunya virus vectors

Numerous recent studies have illuminated global distributions of human cases of dengue and other mosquito-transmitted diseases, yet the potential distributions of key vector species have not been incorporated integrally into those mapping efforts. Projections onto future conditions to illuminate potential distributional shifts in coming decades are similarly lacking, at least outside Europe. This study examined the global potential distributions of Aedes aegypti and Aedes albopictus in relation to climatic variation worldwide to develop ecological niche models that, in turn, allowed anticipation of possible changes in distributional patterns into the future. Results indicated complex global rearrangements of potential distributional areas, which—given the impressive dispersal abilities of these two species—are likely to translate into actual distributional shifts. This exercise also signalled a crucial priority: digitization and sharing of existing distributional data so that models of this sort can be developed more rigorously, as present availability of such data is fragmentary and woefully incomplete.     

High concentrations of circulating interleukin-6 and monocyte chemotactic protein-1 with low concentrations of interleukin-8 were associated with severe chikungunya fever during the 2009-2010 outbreak in Thailand

The recent outbreak of Chikungunya virus in Thailand caused a rheumatic fever associated with considerable morbidity and fatalities. Thus, it is important to identify biomarker(s) of severe disease induced by this threatening arbovirus. Putative biomarkers in cases of chikungunya fever during an outbreak in the southern part of Thailand in 2009-2010 were identified. Sixty-two patients who had developed fever and myalgia, with or without arthralgia/arthritis, were enrolled and grouped into severe chikungunya fever (CHIKF) (n= 15), mild CHIKF (n= 20) and non-CHIKF (n= 27) to investigate circulating immunological mediators that might serve as markers of severity. Blood samples were taken at presentation (day 1) and 30 days later (day 30) and plasma concentrations of interleukin (IL)-1β, IL-6, IL-8, IL-17, tumor necrosis factor-alpha, monocyte chemotactic protein-1 (MCP-1), matrix metalloproteinase-1, tissue inhibitor of matrix metalloproteinase-1 and viral load were measured by ELISA. On day 1, severe CHIKF and mild CHIKF groups had viral loads of 10(8.5) and 10(8.3) of RNA copies/mL, respectively. At presentation, all CHIKF patients had circulating concentrations of IL-6 and MCP-1 higher than did non-CHIKF patients, whereas amongst the CHKF patients, the severe CHIKF patients had higher IL-6 concentrations than did mild CHIKF patients. Interestingly, severe CHIKF patients had significantly lower concentrations of circulating IL-8 than the other groups of patients, suggesting that high concentrations of IL-6 and MCP-1 with low concentrations of IL-8 may be a determinant of severe chikungunya virus infection.     

Comparative sequences of two type 1 dengue virus strains possessing different growth characteristics in vitro

The complete genome sequences of two dengue-1 virus strains having different growth characteristics (Mochizuki and A88) were compared with other published strains. The sequence analysis indicated several unique amino acid changes throughout the coding region of Mochizuki strain, mostly in envelope (E) protein. A unique amino acid, Ile-69 for Mochizuki strain at E protein resulted in the loss of an Asn-67-linked glycosylation site. A Thr substitution for Ala-114 at C protein and amino acid changes found in E, non-structural NS3, NS4a, and NS5 proteins were unique for A88 strain. These substitutions might be correlated to their different growth characteristics in vitro.     

Extensive evolution analysis of the global chikungunya virus strains revealed the origination of CHIKV epidemics in Pakistan in 2016

Chikungunya virus (CHIKV) is a mosquito-borne virus that causes epidemics widely in the world especially in the tropical and subtropical regions. Phylogenetic analysis has found that the CHIKV lineages were associated with the spatial and temporal distributions, which were related to the virus adaption to the major mosquito species and their distributions. In this study, we reported the complete genome sequences of eight CHIKV isolates from the outbreak in Pakistan last year. Then we reviewed the evolutionary history using extensive phylogenetic analysis, analyzed lineage-specific substitutions in viral proteins, and characterized the spreading pathway of CHIKV strains including the Pakistani strains. The results showed that the Pakistani stains belonged to the ECSA.IOL sub-lineage and derived from India. The genetic properties of the Pakistani strains including the adaptive substitution to vectors were further characterized, and the potential risks from the occurrence of CHIKV infection in Pakistan were discussed. These results provided better understanding of CHIKV evolution and transmission in the world and revealed the possible origination of the CHIKV outbreak and epidemic in Pakistan, which would promote the disease prevention and control in the identified countries and territories with the history of CHIKV infections as well as new regions with potential risk of CHIKV outbreaks.

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Isolation and characterization of dengue virus serotype 2 from the large dengue outbreak in Guangdong,China in 2014

Dengue has been well recognized as a global public health threat,but only sporadic epidemics and imported cases were reported in recent decades in China.Since July 2014,an unexpected large dengue outbreak has occurred in Guangdong province,China,resulting in more than 40000 patients including six deaths.To clarify and characterize the causative agent of this outbreak,the acute phase serum from a patient diagnosed with severe dengue was subjected to virus isolation and high-throughput sequencing(HTS).Traditional real-time RT-PCR and HTS with Ion Torrent PGM detected the presence of dengue virus serotype 2(DENV-2).A clinical DENV-2 isolate GZ05/2014 was obtained by culturing the patient serum in mosquito C6/36 cells.The complete genome of GZ05/2014 was determined and deposited in Gen Bank under the access number KP012546.Phylogenetic analysis based on the complete envelope gene showed that the newly DENV-2 isolate belonged to Cosmopolitan genotype and clustered closely with other Guangdong strains isolated in the past decade.No amino acid mutations that are obviously known to increase virulence or replication were identified throughout the genome of GZ05/2014.The high homology of Guangdong DENV-2 strains indicated the possibility of establishment of local DENV-2 circulation in Guangdong,China.These results help clarify the origin of this epidemic and predict the future status of dengue in China.     

Molecular evidence of occurrence of Tomato Leaf Curl New Delhi Virus infecting cucurbits in several states in India

Abstract

Tomato Leaf Curl New Delhi Virus (ToLCNDV) is an important begomovirus constraint to the production of cucurbitaceous and other crops in India and its subcontinent. In this study first time, symptomatic samples of different cucurbits were collected from Telangana, Uttar Pradesh (Varanasi) and Madhya Pradesh location in India. The symptomatic samples were associated with begomovirus infection was confirmed by PCR amplification using specific universal primers Deng 540/541. Thirteen out of fifteen samples were amplified with newly designed bipartite specific primers JKR 58?F and JKR 59?R. In eleven out of thirteen bipartite samples contain betasatellite, confirmed by PCR amplification using specific primer CLB36F and CLB37R. The amplified PCR product with JKR58F and 59R of bitter gourd sample collected from Telangana was sequenced. The sequence was share 97.53% similarity with ToLCNDV infecting bottle gourd in Haryana in India (FN645905). Phylogenic analysis revealed that ToLCNDV infecting cucurbits are different, from ToLCNDV infecting tomato.     

The changing epidemiology of dengue in Delhi, India

The distribution of deformed wing virus infection within the honey bee reproductive castes (queens, drones) was investigated by in situ hybridization and immunohistology from paraffin embedded sections. Digoxygenin or CY5.5 fluorochrome end-labelled nucleotide probes hybridizing to the 3' portion of the DWV genome were used to identify DWV RNA, while a monospecific antibody to the DWV-VP1 structural protein was used to identify viral proteins and particles. The histological data were confirmed by quantitative RT-PCR of dissected organs. Results showed that DWV infection is not restricted to the digestive tract of the bee but spread in the whole body, including queen ovaries, queen fat body and drone seminal vesicles.     

Study on immunity of dengue virus and dengue vaccine development

In the study of vaccines for dengue viruses, which are multivalent immunization, genetically and antigenically distinct, we should have more sophisticated understanding of viral immune physiology. Because the immune response to dengue and its role in the pathophysiology of dengue fever and dengue hemorrhagic fever are multifaceted, several different efforts have been made to engineer a protective vaccine. Because of space limitations, this review is focused only on vaccines that have emerged from preclinical studies into clinical trial.     

Study on immunity of dengue virus and dengue vaccine development

In the study of vaccines for dengue viruses,which are multivalent immunization,genetically and antigenically distinct,we should have more sophisticated understanding of viral immune physiology.Because the immune response to dengue and its role in the pathophysiology of dengue fever and dengue hemorrhagic fever are multifaceted,several different efforts have been made to engineer a protective vaccine.Because of space limitations,this review is focused only on vaccines that have emerged from preclinical studies into clinical trial.     

Molecular characterization of chikungunya virus from three regions of Cameroon

<正>Dear Editor,Chikungunya virus(CHIKV),a single-stranded RNA virus that belongs to the genus Alphavirus,family Togaviridae,is transmitted by mosquitoes of the genus Aedes(Diptera:Culicidae),predominantly Aedes aegypti and A.albopictus(Staples et al.,2014).CHIKV infection is most often characterized by fever,headache,     

Three-way interactions between mosquito population,viral strain and temperature underlying chikungunya virus transmission potential

Interactions between pathogens and their insect vectors in nature are under the control of both genetic and non-genetic factors, yet most studies on mosquito vector competence for human pathogens are conducted in laboratory systems that do not consider genetic and/or environmental variability. Evaluating the risk of emergence of arthropod-borne viruses (arboviruses) of public health importance such as chikungunya virus (CHIKV) requires a more realistic appraisal of genetic and environmental contributions to vector competence. In particular, sources of variation do not necessarily act independently and may combine in the form of interactions. Here, we measured CHIKV transmission potential by the mosquito Aedes albopictus in all combinations of six worldwide vector populations, two virus strains and two ambient temperatures (20°C and 28°C). Overall, CHIKV transmission potential by Ae. albopictus strongly depended on the three-way combination of mosquito population, virus strain and temperature. Such genotype-by-genotype-by-environment (G × G × E) interactions question the relevance of vector competence studies conducted with a simpler set of conditions. Our results highlight the need to account for the complex interplay between vectors, pathogens and environmental factors to accurately assess the potential of vector-borne diseases to emerge.     

Implications of previous subclinical dengue infection but not virus load in dengue hemorrhagic fever

In a study comparing the virus load and immune reaction between patients with primary and secondary dengue-2 (DEN-2) infections in a hospital-based analysis, we found that 40.7% (55/135) of the 135 patients had secondary DEN-2 infection following a DEN-2 outbreak in southern Taiwan. Most of the secondary infections had subclinical primary dengue infections (78.2%; 43/55). Patients with secondary DEN-2 infections had lower platelet counts, and blood interferon-alpha and virus load, but significantly higher interleukin-10 (P=0.030) and anti-DEN-1 neutralization titers (P=0.013) than those with primary infection. Patients with secondary DEN-2 infection also had a higher rate of dengue hemorrhagic fever (DHF) (61.7% vs. 36.3%). A previous subclinical dengue infection is involved in the secondary DEN-2 infection associated with altered immune reaction and higher DHF rate, but lower blood virus load.     

Molecular epidemiology demonstrates that imported and local strains circulated during the 2014 dengue outbreak in Guangzhou,China

The dengue virus(DENV) is a vital global public health issue. The 2014 dengue epidemic in Guangzhou, China, caused approximately 40,000 cases of infection and five deaths. We carried out a comprehensive investigation aimed at identifying the transmission sources in this dengue epidemic. To analyze the phylogenetics of the 2014 dengue strains, the envelope(E) gene sequences from 17 viral strains isolated from 168 dengue patient serum samples were sequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype Ⅰ strains, including 8genotype Ⅰ and 9 genotype V strains. Additionally, 6 genotype Ⅰ strains that were probably introduced to China from Thailand before 2009 were widely transmitted in the 2013 and 2014 epidemics, and they continued to circulate until 2015, with one affinis strain being found in Singapore. The other 2 genotype Ⅰ strains were introduced from the Malaya Peninsula in 2014. The transmission source of the 9 genotype Ⅴ strains was from Malaysia in 2014. DENVs of different serotypes and genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, not only had DENV been imported to Guangzhou, but it had also been gradually exported, as the viruses exhibited an enzootic transmission cycle in Guangzhou.     

Molecular engineering and plant expression of an immunoglobulin heavy chain scaffold for delivery of a dengue vaccine candidate

In order to enhance vaccine uptake by the immune cells in vivo, molecular engineering approach was employed to construct a polymeric immunoglobulin G scaffold (PIGS) that incorporates multiple copies of an antigen and targets the Fc gamma receptors on antigen‐presenting cells. These self‐adjuvanting immunogens were tested in the context of dengue infection, for which there is currently no globally licensed vaccine yet. Thus, the consensus domain III sequence (cEDIII) of dengue glycoprotein E was incorporated into PIGS and expressed in both tobacco plants and Chinese Ovary Hamster cells. Purified mouse and human cEDIII‐PIGS were fractionated by HPLC into low and high molecular weight forms, corresponding to monomers, dimers and polymers. cEDIII‐PIGS were shown to retain important Fc receptor functions associated with immunoglobulins, including binding to C1q component of the complement and the low affinity Fcγ receptor II, as well as to macrophage cells in vitro. These molecules were shown to be immunogenic in mice, with or without an adjuvant, inducing a high level IgG antibody response which showed a neutralizing potential against the dengue virus serotype 2. The cEDIII‐PIGS also induced a significant cellular immune response, IFN‐γ production and polyfunctional T cells in both the CD4⁺ and CD8⁺ compartments. This proof‐of‐principle study shows that the potent antibody Fc‐mediated cellular functions can be harnessed to improve vaccine design, underscoring the potential of this technology to induce and modulate a broad‐ranging immune response.     

登革病毒衣壳蛋白在大肠杆菌中的表达及其自组装活性的研究

采用高保真RT-PCR自登革2型病毒43株基因组RNA中扩增全长C基因及缺失羧基端Cv片段,分别构建可表达C及Cv的重组质粒pLEX—C和pLEX—Cv,转化E．coliGI724后用色氨酸诱导表达。经SDS—PAGE分析,表达的C及Cv蛋白相对分子质量分别约为12000和10000,分别约占菌体蛋白总量的19％和13％。Western印迹检测表明重组表达的C蛋白均可被特异识别登革病毒衣壳蛋白的单克隆抗体特异识别。表达的蛋白经过硫酸铵沉淀和蔗糖密度梯度离心后,通过琼脂糖凝胶电泳和负染电镜均未能检测到衣壳样颗粒的存在,说明登革病毒衣壳蛋白可能不具体外自组装活性。     

Incidence of lab-confirmed dengue fever in a pediatric cohort in Delhi,India

BackgroundOur aim was to estimate the overall and age-specific incidence of lab-confirmed dengue fever using ELISA based assays among children 6 months to 15 years in Delhi.MethodsWe enrolled a cohort of 984 children aged 6 months to <14 years in South Delhi and followed-up weekly for fever for 24 months or till 15 completed years of child-age. Households of the enrolled children were geo-tagged. NS1, IgM and IgG assays were conducted using ELISA method to confirm dengue fever in children with ≥3 consecutive days of fever. Molecular typing was done in a subset of NS1 positive cases to identify the circulating serotypes.Principal findingsWe had a total of 1953 person-years (PY) of follow up. Overall, there were 4208 episodes of fever with peaks during June to November. The overall incidence (95%CI) of fever was 215/100 PY (209 to 222). A total of 74/1250 3-day fever episodes were positive for acute dengue fever (NS1 and/or IgM positive). The overall incidence (95%CI) of acute dengue fever was 37.9 (29.8 to 47.6) per 1000 PY; highest among children aged 5 to 10 years (50.4 per 1000 PY, 95% CI 36.5 to 67.8). Spatial autocorrelation analysis suggested a clustering pattern for the dengue fever cases (Moran’s Index 0.35, z-score 1.8, p = 0.06). Dengue PCR was positive in 16 of the 24 specimens tested; DEN 3 was the predominant serotype identified in 15/24 specimens.ConclusionsWe found a high incidence of dengue fever among under 15-year children with clustering of cases in the community. DEN 3 was the most commonly circulating strain encountered. The findings underscore the need for development of affordable pre-vaccination screening strategy as well as newer dengue vaccines for young children while continuing efforts in vector control.     

Molecular docking studies of chloroquine and its derivatives against P23pro-zbd domain of chikungunya virus: Implication in designing of novel therapeutic strategies

The arthropod-transmitted chikungunya virus has emerged as an epidemic menace that causes debilitating polyarthritis. With this life-threatening impact on humans, the possible treatment requires to cure the viral infectivity. But, devoid of any vaccine against the chikungunya virus (CHIKV), there is a need to develop a novel chemotherapeutic strategy to treat this noxious infection. CHIKV carries highly compact P23^pro-zbd structure that possesses potential RNA-binding surface domains which extremely influences the use of RNA template during genome replication at the time of infection and pathogenesis. Therefore, computational approaches were used to explore the novel small molecule inhibitors targeting P23^pro-zbd domain. The tertiary structure was modeled and optimized using in silico approaches. The results obtained from PROCHECK (93.1% residues in favored regions), ERRAT (87.480 overall model quality) and ProSA (Z-score: −11.72) revealed the reliability of the proposed model. Interestingly, a previously reported inhibitor, chloroquine possesses good binding affinities with the target domain. In-depth analysis revealed that chloroquine derivatives such as didesethyl chloroquine hydroxyacetamide, cletoquine, hydroxychloroquine exhibited a better binding affinity. Notably, MD simulation analysis exhibited that Thr1312, Ala1355, Ala1356, Asn1357, Asp1364, Val1366, Cys1367, Ala1401, Gly1403, Ser1443, Tyr1444, Gly1445, Asn1459, and Thr1463 residues are the key amino acid responsible for stable ligand-protein interaction. The results obtained from this study provide new insights and advances the understanding to develop a new approach to consider effective and novel drug against chikungunya. However, a detailed in vivo study is required to explore its drug likeliness against this life-threatening disease.