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Impact of Chikungunya Virus on Aedes albopictus Females and Possibility of Vertical Transmission Using the Actors of the 2007 Outbreak in Italy  [PDF]
Romeo Bellini, Anna Medici, Mattia Calzolari, Paolo Bonilauri, Francesca Cavrini, Vittorio Sambri, Paola Angelini, Michele Dottori
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0028360
Abstract: We investigated the impact of CHIKV strains on some Aedes albopictus (Skuse) reproductive parameters and the possibility of vertical transmission. Two strains were collected in the area where the epidemic occurred in 2007, one isolated from mosquitoes, the other one isolated from a viraemic patient. Different types of blood meals, either infected or non-infected, were offered to Ae. albopictus females, that were then analyzed at increasing time post infection. The virus titre, measured by two RT-PCR methods in the blood meals, influenced the rate of infection and the rate of dissemination of CHIKV in Ae. albopictus body. We found individual variability with respect to the infection/dissemination rates and their latency both considering the female's body and appendages. The hatching rate was significantly lower for the eggs laid by the infected females than for the control eggs, while the mortality during the larval development (from first instar larva to adult emergence) was similar among the progeny of infected and non-infected female groups. Our findings seem to support the hypothesis that the vertical transmission is a rare event under our conditions, and that a certain time period is required in order to get the ovarioles infected. Field observations conducted during the Spring 2008 showed no evidence of the presence of infected overwintering progeny produced by Ae. albopictus females infected during the 2007 outbreak.
Spatial and Temporal Clustering of Chikungunya Virus Transmission in Dominica  [PDF]
Elaine O. Nsoesie?,R. Paul Ricketts?,Heidi E. Brown?,Durland Fish?,David P. Durham?,Martial L. Ndeffo Mbah?,Trudy Christian?,Shalauddin Ahmed?,Clement Marcellin?,Ellen Shelly
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0003977
Abstract: Using geo-referenced case data, we present spatial and spatio-temporal cluster analyses of the early spread of the 2013–2015 chikungunya virus (CHIKV) in Dominica, an island in the Caribbean. Spatial coordinates of the locations of the first 417 reported cases observed between December 15th, 2013 and March 11th, 2014, were captured using the Global Positioning System (GPS). We observed a preponderance of female cases, which has been reported for CHIKV outbreaks in other regions. We also noted statistically significant spatial and spatio-temporal clusters in highly populated areas and observed major clusters prior to implementation of intensive vector control programs suggesting early vector control measures, and education had an impact on the spread of the CHIKV epidemic in Dominica. A dynamical identification of clusters can lead to local assessment of risk and provide opportunities for targeted control efforts for nations experiencing CHIKV outbreaks.
Chikungunya Virus Transmission Potential by Local Aedes Mosquitoes in the Americas and Europe  [PDF]
Anubis Vega-Rúa?,Ricardo Louren?o-de-Oliveira?,Laurence Mousson?,Marie Vazeille?,Sappho Fuchs?,André Yébakima?,Joel Gustave?,Romain Girod?,Isabelle Dusfour?,Isabelle Leparc-Goffart
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0003780
Abstract: Background Chikungunya virus (CHIKV), mainly transmitted in urban areas by the mosquitoes Aedes aegypti and Aedes albopictus, constitutes a major public health problem. In late 2013, CHIKV emerged on Saint-Martin Island in the Caribbean and spread throughout the region reaching more than 40 countries. Thus far, Ae. aegypti mosquitoes have been implicated as the sole vector in the outbreaks, leading to the hypothesis that CHIKV spread could be limited only to regions where this mosquito species is dominant. Methodology/Principal Findings We determined the ability of local populations of Ae. aegypti and Ae. albopictus from the Americas and Europe to transmit the CHIKV strain of the Asian genotype isolated from Saint-Martin Island (CHIKV_SM) during the recent epidemic, and an East-Central-South African (ECSA) genotype CHIKV strain isolated from La Réunion Island (CHIKV_LR) as a well-characterized control virus. We also evaluated the effect of temperature on transmission of CHIKV_SM by European Ae. albopictus. We found that (i) Aedes aegypti from Saint-Martin Island transmit CHIKV_SM and CHIKV_LR with similar efficiency, (ii) Ae. aegypti from the Americas display similar transmission efficiency for CHIKV_SM, (iii) American and European populations of the alternative vector species Ae. albopictus were as competent as Ae. aegypti populations with respect to transmission of CHIKV_SM and (iv) exposure of European Ae. albopictus to low temperatures (20°C) significantly reduced the transmission potential for CHIKV_SM. Conclusions/Significance CHIKV strains belonging to the ECSA genotype could also have initiated local transmission in the new world. Additionally, the ongoing CHIKV outbreak in the Americas could potentially spread throughout Ae. aegypti- and Ae. albopictus-infested regions of the Americas with possible imported cases of CHIKV to Ae. albopictus-infested regions in Europe. Colder temperatures may decrease the local transmission of CHIKV_SM by European Ae. albopictus, potentially explaining the lack of autochthonous transmission of CHIKV_SM in Europe despite the hundreds of imported CHIKV cases returning from the Caribbean.
Simultaneous Effects of Control Measures on the Transmission Dynamics of Chikungunya Disease
Applied Mathematics , 2012, DOI: 10.5923/j.am.20120204.05
Abstract: Chikungunya is a vector borne communicable disease which is transmitted in human population through the bite of an infected Aedes-Aegeypti mosquito. In order to study the spread of Chikungunya disease a model has been proposed and analyzed in this paper. In the proposed model the human population and the mosquito population have been divided into three and two classes respectively. For controlling the disease, vector control measures such as, reduction in the breeding of vector population, killing of mosquitoes and isolation of infected humans have been also taken in to account in the model. Linear and non-linear stability analysis of the model has been carried out. From the analysis we have derived a threshold condition involving control reproductive number, and we have found that the disease free equilibrium point is locally asymptotically stable whenand unstable when.We have also proved that a unique endemic equilibrium point exists and is locally asymptotically stable when. Thus, we have concluded from the analysis of the model that the disease will either die out or will remain endemic depending on the value of control reproductive number. This study will assist the health department in controlling the spread of Chikungunya disease by introducing the control measures such as increasing the awareness in the society, killing of mosquitoes and isolating the infected individuals.
Modelling the Effects of Vertical Transmission in Mosquito and the Use of Imperfect Vaccine on Chikungunya Virus Transmission Dynamics  [PDF]
Martins O. Onuorah, Emmanuel I. Obi, Bala G. Babangida
Applied Mathematics (AM) , 2019, DOI: 10.4236/am.2019.104019
Abstract: In this paper, a deterministic mathematical model for Chikungunya virus (Chikv) transmission and control is developed and analyzed to underscore the effect of vaccinating a proportion of the susceptible human, and vertical transmission in mosquito population. The disease free, and endemic equilibrium states were obtained and the conditions for the local and global stability or otherwise were given. Sensitivity analysis of the effective reproductive number,Rc(the number of secondary infections resulting from the introduction of a single infected individual into a population where a proportion is fairly protected) shows that the recruitment rate of susceptible mosquito (ΛM) and the proportion of infectious new births from infected mosquito (β)?are the most sensitive parameters. Bifurcation analysis of the model using center manifold theory reveals that the model undergoes backward bifurcation (coexistence of disease free and endemic equilibrium when Rc< 1 ). Numerical simulation of the model shows that vaccination of susceptible human population with imperfect vaccine will have a positive impact and that vertical transmission in mosquito population has a negligible effect. To the best of our knowledge, our model is the first to incorporate vaccinated human compartment and vertical transmission in (Chikv) model.
Evidence of Experimental Vertical Transmission of Emerging Novel ECSA Genotype of Chikungunya Virus in Aedes aegypti  [PDF]
Ankita Agarwal,Paban Kumar Dash ,Anil Kumar Singh,Shashi Sharma,Natarajan Gopalan,Putcha Venkata Lakshmana Rao,Man Mohan Parida,Paul Reiter
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002990
Abstract: Background Chikungunya virus (CHIKV) has emerged as one of the most important arboviruses of public health significance in the past decade. The virus is mainly maintained through human-mosquito-human cycle. Other routes of transmission and the mechanism of maintenance of the virus in nature are not clearly known. Vertical transmission may be a mechanism of sustaining the virus during inter-epidemic periods. Laboratory experiments were conducted to determine whether Aedes aegypti, a principal vector, is capable of vertically transmitting CHIKV or not. Methodology/Principal Findings Female Ae. aegypti were orally infected with a novel ECSA genotype of CHIKV in the 2nd gonotrophic cycle. On day 10 post infection, a non-infectious blood meal was provided to obtain another cycle of eggs. Larvae and adults developed from the eggs obtained following both infectious and non-infectious blood meal were tested for the presence of CHIKV specific RNA through real time RT-PCR. The results revealed that the larvae and adults developed from eggs derived from the infectious blood meal (2nd gonotrophic cycle) were negative for CHIKV RNA. However, the larvae and adults developed after subsequent non-infectious blood meal (3rd gonotrophic cycle) were positive with minimum filial infection rates of 28.2 (1:35.5) and 20.2 (1:49.5) respectively. Conclusion/Significance This study is the first to confirm experimental vertical transmission of emerging novel ECSA genotype of CHIKV in Ae. aegypti from India, indicating the possibilities of occurrence of this phenomenon in nature. This evidence may have important consequence for survival of CHIKV during adverse climatic conditions and inter-epidemic periods.
Chikungunya Virus Neutralization Antigens and Direct Cell-to-Cell Transmission Are Revealed by Human Antibody-Escape Mutants  [PDF]
Chia Yin Lee,Yiu-Wing Kam,Jan Fric,Benoit Malleret,Esther G. L. Koh,Celine Prakash,Wen Huang,Wendy W. L. Lee,Cui Lin,Raymond T. P. Lin,Laurent Renia,Cheng-I Wang,Lisa F. P. Ng,Lucile Warter
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002390
Abstract: Chikungunya virus (CHIKV) is an alphavirus responsible for numerous epidemics throughout Africa and Asia, causing infectious arthritis and reportedly linked with fatal infections in newborns and elderly. Previous studies in animal models indicate that humoral immunity can protect against CHIKV infection, but despite the potential efficacy of B-cell-driven intervention strategies, there are no virus-specific vaccines or therapies currently available. In addition, CHIKV has been reported to elicit long-lasting virus-specific IgM in humans, and to establish long-term persistence in non-human primates, suggesting that the virus might evade immune defenses to establish chronic infections in man. However, the mechanisms of immune evasion potentially employed by CHIKV remain uncharacterized. We previously described two human monoclonal antibodies that potently neutralize CHIKV infection. In the current report, we have characterized CHIKV mutants that escape antibody-dependent neutralization to identify the CHIKV E2 domain B and fusion loop “groove” as the primary determinants of CHIKV interaction with these antibodies. Furthermore, for the first time, we have also demonstrated direct CHIKV cell-to-cell transmission, as a mechanism that involves the E2 domain A and that is associated with viral resistance to antibody-dependent neutralization. Identification of CHIKV sub-domains that are associated with human protective immunity, will pave the way for the development of CHIKV-specific sub-domain vaccination strategies. Moreover, the clear demonstration of CHIKV cell-to-cell transmission and its possible role in the establishment of CHIKV persistence, will also inform the development of future anti-viral interventions. These data shed new light on CHIKV-host interactions that will help to combat human CHIKV infection and inform future studies of CHIKV pathogenesis.
A Review Of Chikungunya  [cached]
Bincy Thomas,A.R.Tekade,Pande V.V
Pharmaceutical Reviews , 2007,
Abstract: Vaccines and new drugs against chikungunya are urgently needed. Chikungunya is generally not fatal.However, in 2005-2007, many deaths have been associated with chikungunya worldwide and still it is continuing. Currently there is no vaccine and fully satisfied drugs to treat all symptoms of chikungunya.Treatment are just symptomatic and in many cases improper use of NSAIDS leads to more complications. Every year 1000s are getting infected and many are dying. So it is high time to turn health organisation’s concentration to find a solution for this health issue.IntroductionThe word chikungunya meaning "that which bends up", which is derived from its arthritic symptoms. It is the hottest topic of discussion among public today, so is necessary to know the causes, symptoms, treatment and preventive measures of this viral fever. Usually chikungunya virus or CHIKV is spread by mosquito bites from Aedes aegypti mosquitoes, Aedes albopictus (Tiger mosquito), Aedes luteocephalus, or A. taylori.. There is no reported case of human-human transmission of CHIKV. The outbreak of infection and studies about it reveals that people living near to forest and water stores are more prone to this viral desease, since these areas provide better environment for mosquito breeding.High fever and arthritic pain, especially severe pain on extremes is characteristic of chikungunya fever. In allopathic, treatment is based on the symptoms and no preventive drugs are available. Siddha system claims some medicines for both treatment and prevention, but is not scientifically proven. By taking proper precaution against mosquito bites by using insecticides, repellents and other measures, transmission of CHIKV can be prevented to greater extent.
Failure to demonstrate experimental vertical transmission of the epidemic strain of Chikungunya virus in Aedes albopictus from La Réunion Island, Indian Ocean
Vazeille, Marie;Mousson, Laurence;Failloux, Anna-Bella;
Memórias do Instituto Oswaldo Cruz , 2009, DOI: 10.1590/S0074-02762009000400017
Abstract: aedes albopictus was responsible for transmission in the first outbreak of chikungunya (chik) on la réunion island, indian ocean, in 2005-2006. the magnitude of the outbreak on this island, which had been free of arboviral diseases for over 30 years, as well as the efficiency of ae. albopictus as the main vector, raises questions about the maintenance of the chik virus (chikv) through vertical transmission mechanisms. few specimens collected from the field as larvae were found to be infected. in this study, ae. albopictus originating from la réunion were orally infected with a blood-meal containing 108 pfu/ml of the chikv epidemic strain (chikv 06.21). eggs from the first and second gonotrophic cycles were collected and raised to the adult stage. the infectious status of the progeny was checked (i) by immunofluorescence on head squashes of individual mosquitoes to detect the presence of viral particles or (ii) by quantitative rt-pcr on mosquito pools to detect viral rna. we analysed a total of 1,675 specimens from the first gonotrophic cycle and 1,709 from the second gonotrophic cycle without detecting any viral particles or viral rna. these laboratory results are compared to field records.
Functional processing and secretion of Chikungunya virus E1 and E2 glycoproteins in insect cells
Stefan W Metz, Corinne Geertsema, Byron E Martina, Paulina Andrade, Jacco G Heldens, Monique M van Oers, Rob W Goldbach, Just M Vlak, Gorben P Pijlman
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-353
Abstract: Expression in the presence of either tunicamycin or furin inhibitor showed that a substantial portion of recombinant intracellular E1 and precursor E3E2 was glycosylated, but that a smaller fraction of E3E2 was processed by furin into mature E3 and E2. Deletion of the C-terminal transmembrane domains of E1 and E2 enabled secretion of furin-cleaved, fully processed E1 and E2 subunits, which could then be efficiently purified from cell culture fluid via metal affinity chromatography. Confocal laser scanning microscopy on living baculovirus-infected Sf21 cells revealed that full-length E1 and E2 translocated to the plasma membrane, suggesting similar posttranslational processing of E1 and E2, as in a natural CHIKV infection. Baculovirus-directed expression of E1 displayed fusogenic activity as concluded from syncytia formation. CHIKV-E2 was able to induce neutralizing antibodies in rabbits.Chikungunya virus glycoproteins could be functionally expressed at high levels in insect cells and are properly glycosylated and cleaved by furin. The ability of purified, secreted CHIKV-E2 to induce neutralizing antibodies in rabbits underscores the potential use of E2 in a subunit vaccine to prevent CHIKV infections.Chikungunya virus (CHIKV) is an arthropod-borne (arbo)virus that causes epidemics in Africa, India and South-East Asia [1]. Recent outbreaks in Italy in 2007 [2] and autochthonous transmission events in France in 2010 [3] exemplify the threat of continued spread of CHIKV in the Western world, which correlates with the concurrent expanding distribution of its insect vector. CHIKV is maintained in a sylvatic transmission cycle of mosquitoes, rodents and primates, with Aedes aegyti as the primary vector. However, the responsible vector causing the severe CHIKV epidemic on the Reunion Islands in 2005/2006 was Ae. albopictus [4]. This vector switch made the virus endemic in more temperate regions and resulted in the first European cases (Italy, 2007) of transmission by local
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