Fitness adaptations of Japanese encephalitis virus in pigs following vector-free serial passaging.

Japanese encephalitis virus (JEV) is a zoonotic mosquito-transmitted Flavivirus circulating in birds and pigs. In humans, JEV can cause severe viral encephalitis with high mortality. Considering that vector-free direct virus transmission was observed in experimentally infected pigs, JEV introduction into an immunologically naïve pig population could result in a series of direct transmissions disrupting the alternating host cycling between vertebrates and mosquitoes. To assess the potential consequences of such a realistic scenario, we passaged JEV ten times in pigs. This resulted in higher in vivo viral replication, increased shedding, and stronger innate immune responses in pigs. Nevertheless, the viral tissue tropism remained similar, and frequency of direct transmission was not enhanced. Next generation sequencing showed single nucleotide deviations in 10% of the genome during passaging. In total, 25 point mutations were selected to reach a frequency of at least 35% in one of the passages. From these, six mutations resulted in amino acid changes located in the precursor of membrane, the envelope, the non-structural 3 and the non-structural 5 proteins. In a competition experiment with two lines of passaging, the mutation M374L in the envelope protein and N275D in the non-structural protein 5 showed a fitness advantage in pigs. Altogether, the interruption of the alternating host cycle of JEV caused a prominent selection of viral quasispecies as well as selection of de novo mutations associated with fitness gains in pigs, albeit without enhancing direct transmission frequency.

Japanese Encephalitis Virus Infection among Wild Caught Vectors Mosquitoes and Domestic Pigs in Northern West Bengal, India.

BACKGROUND: Japanese encephalitis (JE) is an emerging zoonotic disease caused by JE virus (JEV) and transmitted to humans from pigs or aquatic birds by vector mosquitoes in southeast Asian countries. In this study, JEV infection rate among vector mosquitoes and domestic pigs was determined by detecting viral RNA and anti-JEV antibody (immunoglobulin G), respectively. MATERIALS AND METHODS: A total of 146 pool mosquitoes of Culexvishnui subgroup and 278 pig blood samples were analyzed by reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay methods, respectively. E and premembrane (PrM) gene of JEV detected among vectors were sequenced and a phylogenetic tree was constructed. RESULTS: Five (5.81%) pools of Culextritaeniorhynchus were positive for JEV with pooled infection rate 1.70/1000 mosquitoes. A total of 108 (38.84%) blood samples were positive for anti-JEV antibody. Phylogenetic analysis revealed that our own E and PrM gene sequence of JEV belonging to Genotype III and showed 96.95% sequence similarities with the vaccine strain SA14-14-2. CONCLUSION: It was observed that domestic pigs of northern West Bengal were highly infected with JEV. Hence, the transmission should be blocked by pig vaccination. A pilot study may be undertaken for mass vaccination of the prevailing pig population to observe any reduced rate of JEV transmission from both pig to pig and pig to human.

Mosquito Defensins Enhance Japanese Encephalitis Virus Infection by Facilitating Virus Adsorption and Entry within the Mosquito.

Japanese encephalitis virus (JEV) is a viral zoonosis that can cause viral encephalitis, death, and disability. Although the Culex mosquito is the primary vector of JEV, little is known about JEV transmission by this kind of mosquito. Here, we found that mosquito defensin facilitated the adsorption of JEV on target cells via the defensin/lipoprotein receptor-related protein 2 (LRP2) axis. Mosquito defensin bound the ED III domain of the viral envelope (E) protein and directly mediated efficient virus adsorption on the target cell surface; the receptor LRP2, which is expressed on the cell surface, affected defensin-dependent adsorption. As a result, mosquito defensin enhanced JEV infection in the salivary gland, increasing the possibility of viral transmission by mosquitoes. These findings demonstrate the novel role of mosquito defensin in JEV infection and the mechanisms through which the virus exploits mosquito defensin for infection and transmission.IMPORTANCE In this study, we observed the complex roles of mosquito defensin in JEV infection; mosquito defensin exhibited a weak antiviral effect but strongly enhanced binding. In the latter, defensin directly binds the ED III domain of the viral E protein and promotes the adsorption of JEV to target cells by interacting with lipoprotein receptor-related protein 2 (LRP2), thus accelerating virus entry. Together, our results indicate that mosquito defensin plays an important role in facilitating JEV infection and potential transmission.

Insecticide resistance status of three vectors of Japanese encephalitis in east central India.

Japanese encephalitis (JE) has been reported in different districts of Odisha state (east central India) since 1992. During 2016, a major outbreak of JE and acute encephalitis syndrome (AES) occurred in the Malkangiri district of Odisha, causing 103 deaths in children, of which 37 were caused by JE and 66 by AES. Information on insecticide resistance in JE vectors is important for the selection of appropriate insecticides for use in vector control. The present study was designed to determine the resistance status of three important vectors of JE, Culex vishnui, Culex tritaeniorhynchus and Culex bitaeniorhynchus (Diptera: Culicidae), against dichlorodiphenyltrichloroethane (DDT), malathion and deltamethrin in three districts of Odisha state affected by JE. Female adult mosquitoes were collected using mouth aspirators both indoors and outdoors in JE-affected villages and used in susceptibility bioassays following World Health Organization guidelines. Knock-downs were recorded every 10 min up to 1 h and mortality rates were recorded at 24 h post-exposure. Culex vishnui and Cx. tritaeniorhynchus showed resistance to DDT, malathion and deltamethrin, whereas Cx. bitaeniorhynchus was susceptible in all study districts. The information generated by this study will be highly useful in the planning and implementing of appropriate vector control operations for the prevention and control of JE in east central India.

Japanese encephalitis virus-induced neuropathology in mouse model infected through the conjunctival route.

Background & objectives: Mouse is a preferred animal model for studying pathogenesis of Japanese encephalitis virus (JEV) infections, and different routes of inoculation have been tried. Some neurotropic viruses can reach the brain following infection through ocular route. This study was undertaken to establish JEV-induced clinical disease in mouse model through conjunctival route and document the neuropathological effects. Methods: Ten two-week old Swiss albino mice were inoculated with 5 µl Vero cell cultured virus containing 104.7 TCID50 JEV through conjunctival route. Clinical signs of mice were observed twice daily. After necropsy examination, different organs including eyes and olfactory bulbs were collected for histopathological examination, quantification of viral copy number and antigen by real-time TaqMan assay and immunohistochemistry, respectively. Results: Infected mice showed characteristic clinical signs of JE by 4 days post-infection (dpi). Histopathological lesions in brain included perivascular cuffing by mononuclear cells, focal gliosis, necrosis of neurons and neuronophagia and astrocytosis in the cerebrum, cerebellum and the brainstem. JEV viral load was highest in the brain followed by intestine, heart, liver, spleen, lung and kidney. JEV antigen was detected in the bipolar and ganglion cells of the retina and in the mitral cells and periglomerular cells of olfactory bulb and other parts of the brain. Interpretation & conclusions: JEV infection in mice through conjunctival route produced characteristic clinical signs of the disease and neuropathological lesions. Demonstration of JEV antigen in association with neuropathological lesions in the central nervous system and neuronal cells of the eye showed that conjunctival route could be an effective alternate route for virus invasion into the brain. These findings have biosafety implications for researchers, veterinary practitioners and pig farmers.

Japanese Encephalitis Virus Transmitted Via Blood Transfusion, Hong Kong, China.

Japanese encephalitis virus (JEV) is a mosquitoborne virus endemic to China and Southeast Asia that causes severe encephalitis in <1% of infected persons. Transmission of JEV via blood transfusion has not been reported. We report transmission of JEV via blood donation products from an asymptomatic viremic donor to 2 immunocompromised recipients. One recipient on high-dose immunosuppressive drugs received JEV-positive packed red blood cells after a double lung transplant; severe encephalitis and a poor clinical outcome resulted. JEV RNA was detected in serum, cerebrospinal fluid, and bronchoalveolar lavage fluid specimens. The second recipient had leukemia and received platelets after undergoing chemotherapy. This patient was asymptomatic; JEV infection was confirmed in this person by IgM seroconversion. This study illustrates that, consistent with other pathogenic flaviviruses, JEV can be transmitted via blood products. Targeted donor screening and pathogen reduction technologies could be used to prevent transfusion-transmitted JEV infection in highly JEV-endemic areas.

mosGCTL-7, a C-Type Lectin Protein, Mediates Japanese Encephalitis Virus Infection in Mosquitoes.

Japanese encephalitis virus (JEV) is an arthropod-borne flavivirus prevalent in Asia and the Western Pacific and is the leading cause of viral encephalitis. JEV is maintained in a transmission cycle between mosquitoes and vertebrate hosts, but the molecular mechanisms by which the mosquito vector participates in transmission are unclear. We investigated the expression of all C-type lectins during JEV infection in Aedes aegypti The C-type lectin mosquito galactose-specific C-type lectin 7 (mosGCTL-7) (VectorBase accession no. AAEL002524) was significantly upregulated by JEV infection and facilitated infection in vivo and in vitro mosGCTL-7 bound to the N-glycan at N154 on the JEV envelope protein. This recognition of viral N-glycan by mosGCTL-7 is required for JEV infection, and we found that this interaction was Ca2+ dependent. After mosGCTL-7 bound to the glycan, mosPTP-1 bound to mosGCTL-7, promoting JEV entry. The viral burden in vivo and in vitro was significantly decreased by mosPTP-1 double-stranded RNA (dsRNA) treatment, and infection was abolished by anti-mosGCTL-7 antibodies. Our results indicate that the mosGCTL-7/mosPTP-1 pathway plays a key role in JEV infection in mosquitoes. An improved understanding of the mechanisms underlying flavivirus infection in mosquitoes will provide further opportunities for developing new strategies to control viral dissemination in nature.IMPORTANCE Japanese encephalitis virus is a mosquito-borne flavivirus and is the primary cause of viral encephalitis in the Asia-Pacific region. Twenty-four countries in the WHO Southeast Asia and Western Pacific regions have endemic JEV transmission, which exposes >3 billion people to the risks of infection, although JEV primarily affects children. C-type lectins are host factors that play a role in flavivirus infection in humans, swine, and other mammals. In this study, we investigated C-type lectin functions in JEV-infected Aedes aegypti and Culex pipiens pallens mosquitoes and cultured cells. JEV infection changed the expression of almost all C-type lectins in vivo and in vitro, and mosGCTL-7 bound to the JEV envelope protein via an N-glycan at N154. Cell surface mosPTP-1 interacted with the mosGCTL-7-JEV complex to facilitate virus infection in vivo and in vitro Our findings provide further opportunities for developing new strategies to control arbovirus dissemination in nature.

Modelling the skip-and-resurgence of Japanese encephalitis epidemics in Hong Kong.

Japanese encephalitis virus (JEV) is a zoonotic mosquito-borne virus, persisting in pigs, Ardeid birds and Culex mosquitoes. It is endemic to China and Southeastern Asia. The case-fatality ratio (CFR) or the rate of permanent psychiatric sequelae is 30% among symptomatic patients. There were no reported local JEV human cases between 2006 and 2010 in Hong Kong, but it was followed by a resurgence of cases from 2011 to 2017. The mechanism behind this "skip-and-resurgence" patterns is unclear. This work aims to reveal the mechanism behind the "skip-and-resurgence" patterns using mathematical modelling and likelihood-based inference techniques. We found that pig-to-pig transmission increases the size of JEV epidemics but is unlikely to maintain the same level of transmission among pigs. The disappearance of JEV human cases in 2006-2010 could be explained by a sudden reduction of the population of farm pigs as a result of the implementation of the voluntary "pig-rearing licence surrendering" policy. The resurgence could be explained by of a new strain in 2011, which increased the transmissibility of the virus or the spill-over ratio from reservoir to host or both.

Entomological investigation of Japanese encephalitis outbreak in Malkangiri district of Odisha state, India.

BACKGROUND: A severe outbreak of Japanese encephalitis (JE) and acute encephalitis syndrome (AES) with high case fatality was reported from Malkangiri district of Odisha state, India during September to November 2016 affecting 336 children with 103 deaths. OBJECTIVES: The purpose of this study was to investigate the outbreak in the light of entomological determinants. METHODS: Entomological investigation was carried out in 48 villages from four mostly affected Community Health Centres (CHCs) of Malkangiri district. Dusk collections of resting adults was done in villages from indoor and outdoor sites to record the density of mosquito species, including the known JE vectors, feeding behaviour, parity, dusk index and infection status with JE virus (JEV). FINDINGS: The per man hour density and dusk index of JE vector species varied from 2.5 to 24.0 and 0.81 to 7.62, respectively in study villages. A total of 1136 mosquitoes belonging to six vector species were subjected to PCR and one pool of Culex vishnui was found to be positive for JEV. CONCLUSION: The JE transmission in Malkangiri district was confirmed. Thorough screening of human blood samples of JE/AES suspected cases and JE vector mosquitoes for the presence of JEV during rainy season every year is recommended.

Changes of Epidemiological Characteristics of Japanese Encephalitis Viral Infection and Birds as a Potential Viral Transmitter in Korea.

Japanese encephalitis (JE) cases have been increasingly reported recently especially in Seoul and its vicinity. Pigs are known as amplifying host of JE virus (JEV), but do not play an important role in these recent events because pig-breeding is not common in Seoul. The distribution and the density of migratory birds are correlated with JE cases in cities and they might be highly potential hosts contributing to transmit JEV in metropolitan areas. JE genotype and sero-prevalence in birds should be determined for the verification of the transmission route of JEV in the recent sporadic occurrence of JE cases in Seoul.

[Mosquito-transmitted infections]. / Infektionen durch Stechmücken.

Mosquito-transmitted diseases represent one of the greatest health risks when traveling to tropical and sub-tropical countries. Only Japanese encephalitis and yellow fever can be avoided by inoculation, and only malaria can be prevented by chemoprophylaxis. Exposure prophylaxis is the only protection against all other mosquito-born diseases. These infections need to be carefully considered in the differential diagnosis of returning travelers, taking current epidemiology into account. This review discusses common infectious diseases and the options for their diagnosis and therapy.

Epidemiologic Survey of Japanese Encephalitis Virus Infection, Tibet, China, 2015.

We investigated Japanese encephalitis virus (JEV) prevalence in high-altitude regions of Tibet, China, by using standard assays to test mosquitoes, pigs, and humans. Results confirmed that JEV has spread to these areas. Disease prevention and control strategies should be used along with surveillance to limit spread of JEV in high-altitude regions of Tibet.

Incidence of Japanese Encephalitis amongst acute encephalitis syndrome cases in upper Assam districts from 2012 to 2014: A report from a tertiary care hospital.

BACKGROUND & OBJECTIVES: Japanese encephalitis (JE) is a major public health problem in India because of high mortality rate and residual neuropsychiatric damage in the survivors. The present study was undertaken to investigate JE positivity amongst patients admitted with acute encephalitis syndrome (AES) in upper Assam districts and different parameters with their changing trends related to it. METHODS: It was a hospital-based prospective cross-sectional study conducted from January 2012 to December 2014. A total of 1707 consecutive non-repetitive hospitalized patients, satisfying the clinical case definition of AES as per the WHO guidelines, were included in the study. Cerebrospinal fluid (CSF) and serum samples were tested for JEV-specific IgM antibodies. RESULTS: Of the 1707 patients admitted, 696 (40.77 %) were diagnosed as JE with male-to-female ratio 1.7:1 and adult to paediatric ratio 2.2:1. Fever (100%), change in mental status (100%), headache (80.02%), neck rigidity (52.01%), unconsciousness (48.99%), seizure (37.64%) and paralysis (11.06%) were the major clinical findings. The majority of cases (94%) were from rural areas. There was a significant association of JE cases with rainy season of the year i.e., June to August (P<0.001). Overall, 14.94 per cent deaths were reported in JE positive cases. INTERPRETATION & CONCLUSIONS: A higher occurrence of JE was observed in above 15 yr age group. Cases were mainly from rural areas, and there was clustering of cases in rainy season.

Seasonal occurrence of Japanese encephalitis vectors in Bareilly district, Uttar Pradesh, India.

BACKGROUND & OBJECTIVES: Japanese encephalitis (JE) is one of the most common causes of acute encephalitis syndrome in many states of India. Uttar Pradesh state is well known for JE endemicity, contributing 75% of total cases during recent past. Several sporadic cases have been reported from Bareilly region of the state. The disease spread by bite of Culex mosquito. Survey of literature revealed no data on mosquito fauna with reference to JE in this region. Therefore, this study was planned to survey seasonal mosquito population and occurrence of JE vectors in Bareilly region. METHODS: Mosquitoes were sampled on monthly basis from organized pig farm from February 2016 to January 2017 and identified using mosquito identification keys. The meteorological parameters of the area were obtained monthly and standard statistical methods were used to assess the relationship between different weather variables and mosquito population. RESULTS: A total of 4337 mosquitoes belonging to five genera were collected. Mosquitoes of genus Culex were predominant and contributed 84.41% to the total catch. The most dominant species was Cx. tritaeniorhynchus (30.81%), followed by Cx. quinquefasciatus (28.50%), Cx. gelidus (17.24%), Cx. pseudovishnui (11.85%), Cx. vishnui (8.11%), Cx. fuscocephala (2.70%), Cx. infula (0.76%) and Cx. bitaeniorhynchus (0.03%). Pronounced seasonal variation was observed with majority of mosquitoes showing high density in monsoon and post-monsoon period. INTERPRETATION & CONCLUSION: The present study provides knowledge on distribution of JE vector in Bareilly which indicates that the area is at risk of JE outbreak. Abundance of Culex vector clearly demarcates possible threat of JE incidence in the study area. A long-term entomological study is needed to further evaluate the significant role of different weather variables in shaping mosquito densities.

Green synthesis and characterization of silver nanoparticles fabricated using Anisomeles indica: Mosquitocidal potential against malaria, dengue and Japanese encephalitis vectors.

Mosquitoes (Diptera: Culicidae) represent a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. In this scenario, eco-friendly control tools against mosquito vectors are a priority. Green synthesis of silver nanoparticles (AgNP) using a cheap, aqueous leaf extract of Anisomeles indica by reduction of Ag(+) ions from silver nitrate solution has been investigated. Bio-reduced AgNP were characterized by UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of A. indica leaf extract and biosynthesized AgNP was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Both the A. indica leaf extract and AgNP showed dose dependent larvicidal effect against all tested mosquito species. Compared to the leaf aqueous extract, biosynthesized AgNP showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 values of 31.56, 35.21 and 38.08 µg/mL, respectively. Overall, this study firstly shed light on the mosquitocidal potential of A. indica, a potential bioresource for rapid, cheap and effective AgNP synthesis.

Eugenol, α-pinene and ß-caryophyllene from Plectranthus barbatus essential oil as eco-friendly larvicides against malaria, dengue and Japanese encephalitis mosquito vectors.

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Eco-friendly mosquitocides are a priority. In Ayurvedic medicine, Plectranthus species have been used to treat heart disease, convulsions, spasmodic pain and painful urination. In this research, we evaluated the acute toxicity of essential oil from Plectranthus barbatus and its major constituents, against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. The chemical composition of P. barbatus essential oil was analyzed by gas chromatography-mass spectroscopy. Nineteen components were identified. Major constituents were eugenol (31.12%), α-pinene (19.38%) and ß-caryophyllene (18.42%). Acute toxicity against early third-instar larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus was investigated. The essential oil had a significant toxic effect against larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus, with 50% lethal concentration (LC50) values of 84.20, 87.25 and 94.34 µg/ml and 90% lethal concentration (LC90) values of 165.25, 170.56 and 179.58 µg/ml, respectively. Concerning major constituents, eugenol, α-pinene and ß-caryophyllene appeared to be most effective against An. subpictus (LC50 = 25.45, 32.09 and 41.66 µg/ml, respectively), followed by Ae. albopictus (LC50 = 28.14, 34.09 and 44.77 µg/ml, respectively) and Cx. tritaeniorhynchus (LC50 = 30.80, 36.75 and 48.17 µg/ml, respectively). Overall, the chance to use metabolites from P. barbatus essential oil against mosquito vectors seems promising, since they are effective at low doses and could be an advantageous alternative to build newer and safer mosquito control tools.

Eco-friendly larvicides from Indian plants: Effectiveness of lavandulyl acetate and bicyclogermacrene on malaria, dengue and Japanese encephalitis mosquito vectors.

Mosquitoes (Diptera: Culicidae) are a key threat for millions of people and animals worldwide, since they act as vectors for devastating pathogens and parasites, including malaria, dengue, Japanese encephalitis, filiariasis and Zika virus. Mosquito young instars are usually targeted using organophosphates, insect growth regulators and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment and induce resistance in a number of vectors. In this scenario, newer and safer tools have been recently implemented to enhance mosquito control. The concrete potential of screening plant species as sources of metabolites for entomological and parasitological purposes is worthy of attention, as recently elucidated by the Y. Tu's example. Here we investigated the toxicity of Heracleum sprengelianum (Apiaceae) leaf essential oil and its major compounds toward third instar larvae of the malaria vector Anopheles subpictus, the arbovirus vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. GC-MS analysis showed that EO major components were lavandulyl acetate (17.8%) and bicyclogermacrene (12.9%). The EO was toxic to A. subpictus, A. albopictus, and C. tritaeniorhynchus, with LC50 of 33.4, 37.5 and 40.9µg/ml, respectively. Lavandulyl acetate was more toxic to mosquito larvae if compared to bicyclogermacrene. Their LC50 were 4.17 and 10.3µg/ml for A. subpictus, 4.60 and 11.1µg/ml for A. albopictus, 5.11 and 12.5µg/ml for C. tritaeniorhynchus. Notably, the EO and its major compounds were safer to three non-target mosquito predators, Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 206 to 4219µg/ml. Overall, this study highlights that H. sprengelianum EO is a promising source of eco-friendly larvicides against three important mosquito vectors with moderate toxicity against non-target aquatic organisms.

Multiple-Insecticide Resistance and Classic Gene Mutations to Japanese Encephalitis Vector Culex tritaeniorhynchus from China.

Widespread resistance of insect pests to insecticides has been widely reported in China and there is consequently an urgent need to adjust pest management strategies appropriately. This requires detailed information on the extent and causes of resistance. The aim of the present study was to investigate levels of resistance to 5 insecticides among 12 strains of Culex tritaeniorhynchus, a major vector of Japanese encephalitis in China. Resistance to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur were measured using larval bioassays. The allelic frequency of knockdown resistance (kdr) and acetylcholinesterase (AChE) mutations were determined in all strains. Larval bioassay results indicated that the field strains collected from different sites were resistant to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur, with resistance ratio values ranging from 1.70- to 71.98-fold, 7.83- to 43.07-fold, 3.54- to 40.03-fold, 291.85- to 530.89-fold, and 51.32- to 108.83-fold, respectively. A polymerase chain reaction amplification of specific alleles method for individual was developed to detect genotypes of the AChE gene mutation F455W in Cx. tritaeniorhynchus. The frequency of the AChE gene mutation F455W was 100.00% in all strains, making this mutation of no value as a marker of resistance to organophosphorous and carbamate pesticides in Cx. tritaeniorhynchus in China. The kdr allele was present in all strains at frequencies of 10.00-29.55%. Regression analysis indicated a significant correlation between kdr allele frequencies and levels of resistance to deltamethrin, beta-cypermethrin, and permethrin. These results highlight the need to monitor and map insecticide resistance in Cx. tritaeniorhynchus and to adjust pesticide use to minimize the development of resistance in these mosquitoes.

Phylogeographic analysis of Japanese encephalitis virus in India (1956-2012).

Japanese encephalitis virus (JEV) isolates from India phylogenetically belong to two genotypes, III and I. We used envelope gene sequences from GenBank, representing different states of India and other countries, to study the spatiotemporal transmission histories of these two JEV genotypes separately. Genotype III was found to have been successively introduced in the 1930s, 1950s and 1960s, followed by genotype I twice around 2003-2006. Changes in JEV disease patterns in India over the last five decades could thus be attributed to multiple introductions of JEV strains from neighboring Asian countries along with increased transmission potential due to altered ecological settings.

Malathion Resistance Status and Mutations in Acetylcholinesterase Gene (Ace) in Japanese Encephalitis and Filariasis Vectors from Endemic Area in India.

Japanese encephalitis (JE) and lymphatic filariasis (LF) are endemic in estern part of Uttar Pradesh in India and transmitted by Culex mosquitoes (Diptera: Culicidae). JE vaccination and mass drug administration for JE and LF management is being undertaken respectively. In addition to this, indoor residual spraying and fogging are used for the control of mosquito vectors. Organophosphate resistance in mosquito is dependent on alteration in acetylcholinesterase (Ace) gene. Hence, it is important to evaluate organophosphate resistance in Culex tritaeniorhynchus Giles (JE vector) and Culex quinquefasciatus Say (LF vector). The current study showed the presence of resistant populations and F331W mutation in Cx. tritaeniorhynchus and G119S mutation in Cx. quinquefasciatus insensitive Ace genes. Resistant populations of these two vectors increase the chances of spreading of resistance in the natural population and may cause failure of intervention programs that include organophosphates against these two vectors in future.