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Isolation and Genetic Characterization of Japanese Encephalitis Virus Two Decades after Its Elimination in Singapore. Viruses 2022; 14:v14122662. [PMID: 36560666 PMCID: PMC9786948 DOI: 10.3390/v14122662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022] Open
Abstract
Japanese encephalitis virus (JEV) is an important arbovirus in Asia that can cause serious neurological disease. JEV is transmitted by mosquitoes in an enzootic cycle involving porcine and avian reservoirs, in which humans are accidental, dead-end hosts. JEV is currently not endemic in Singapore, after pig farming was abolished in 1992; the last known human case was reported in 2005. However, due to its location along the East-Asian Australasian Flyway (EAAF), Singapore is vulnerable to JEV re-introduction from the endemic regions. Serological and genetic evidence in the last decade suggests JEV's presence in the local fauna. In the present study, we report the genetic characterization and the first isolation of JEV from 3214 mosquito pools consisting of 41,843 Culex mosquitoes, which were trapped from April 2014 to May 2021. The findings demonstrated the presence of genotype I of JEV (n = 10), in contrast to the previous reports of the presence of genotype II of JEV in Singapore. The genetic analyses also suggested that JEV has entered Singapore on several occasions and has potentially established an enzootic cycle in the local fauna. These observations have important implications in the risk assessment and the control of Japanese encephalitis in non-endemic countries, such as Singapore, that are at risk for JEV transmission.
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Yap G, Mailepessov D, Lim XF, Chan S, How CB, Humaidi M, Yeo G, Chong CS, Lam-Phua SG, Lee R, Okumura C, Vythilingam I, Ng LC. Detection of Japanese Encephalitis Virus in Culex Mosquitoes in Singapore. Am J Trop Med Hyg 2020; 103:1234-1240. [PMID: 32700679 PMCID: PMC7470584 DOI: 10.4269/ajtmh.19-0377] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Mosquito-borne flaviviruses are emerging pathogens of an increasing global public health concern because of their rapid increase in geographical range and the impact of climate change. Japanese encephalitis virus (JEV) and West Nile virus (WNV) are of concern because of the risk of reemergence and introduction by migratory birds. In Singapore, human WNV infection has never been reported and human JEV infection is rare. Four sentinel vector surveillance sites were established in Singapore to understand the potential risk posed by these viruses. Surveillance was carried out from August 2011 to December 2012 at Pulau Ubin, from March 2011 to March 2013 at an Avian Sanctuary (AS), from December 2010 from October 2012 at Murai Farmway, and from December 2010 to December 2013 at a nature reserve. The present study revealed active JEV transmission in Singapore through the detection of JEV genotype II in Culex tritaeniorhynchus collected from an Avian Sanctuary. Culex flavivirus (CxFV), similar to the Quang Binh virus isolated from Cx. tritaeniorhynchus in Vietnam and CxFV-LSFlaviV-A20-09 virus isolated in China, was also detected in Culex spp. (vishnui subgroup). No WNV was detected. This study demonstrates the important role that surveillance plays in public health and strongly suggests the circulation of JEV among wildlife in Singapore, despite the absence of reported human cases. A One Health approach involving surveillance, the collaboration between public health and wildlife managers, and control of mosquito populations remains the key measures in risk mitigation of JEV transmission in the enzootic cycle between birds and mosquitoes.
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Affiliation(s)
- Grace Yap
- Environmental Health Institute, National Environment Agency, Singapore
| | - Diyar Mailepessov
- Environmental Health Institute, National Environment Agency, Singapore
| | - Xiao Fang Lim
- Environmental Health Institute, National Environment Agency, Singapore
| | | | | | - Mahathir Humaidi
- Environmental Health Institute, National Environment Agency, Singapore
| | - Gladys Yeo
- Environmental Health Institute, National Environment Agency, Singapore
| | - Chee Seng Chong
- Environmental Health Institute, National Environment Agency, Singapore
| | - Sai Gek Lam-Phua
- Environmental Health Institute, National Environment Agency, Singapore
| | - Ruth Lee
- Environmental Health Institute, National Environment Agency, Singapore
| | | | - Indra Vythilingam
- Parasitology Department, Faculty of Medicine, University of Malaya, Kuala-Lumpur, Malaysia
| | - Lee Ching Ng
- Environmental Health Institute, National Environment Agency, Singapore
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Disentangling etiologies of CNS infections in Singapore using multiple correspondence analysis and random forest. Sci Rep 2020; 10:18219. [PMID: 33106525 PMCID: PMC7588471 DOI: 10.1038/s41598-020-75088-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 10/09/2020] [Indexed: 01/15/2023] Open
Abstract
Central nervous system (CNS) infections cause substantial morbidity and mortality worldwide, with mounting concern about new and emerging neurologic infections. Stratifying etiologies based on initial clinical and laboratory data would facilitate etiology-based treatment rather than relying on empirical treatment. Here, we report the epidemiology and clinical outcomes of patients with CNS infections from a prospective surveillance study that took place between 2013 and 2016 in Singapore. Using multiple correspondence analysis and random forest, we analyzed the link between clinical presentation, laboratory results, outcome and etiology. Of 199 patients, etiology was identified as infectious in 110 (55.3%, 95%-CI 48.3–62.0), immune-mediated in 10 (5.0%, 95%-CI 2.8–9.0), and unknown in 79 patients (39.7%, 95%-CI 33.2–46.6). The initial presenting clinical features were associated with the prognosis at 2 weeks, while laboratory-related parameters were related to the etiology of CNS disease. The parameters measured were helpful to stratify etiologies in broad categories, but were not able to discriminate completely between all the etiologies. Our results suggest that while prognosis of CNS is clearly related to the initial clinical presentation, pinpointing etiology remains challenging. Bio-computational methods which identify patterns in complex datasets may help to supplement CNS infection diagnostic and prognostic decisions.
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Yeo G, Chan S, How CB, Humaidi M, Lim XF, Mailepessov D, Chong CS, Phua-Lam SG, Lee R, Hapuarachchi HC, Ng LC, Yap G. Molecular Analysis of the Bloodmeals of Culex spp. Mosquitoes at Natural Habitats in Singapore to Investigate the Potential Risk of Japanese Encephalitis Virus and West Nile Virus Transmission. Vector Borne Zoonotic Dis 2020; 20:703-714. [PMID: 32931404 DOI: 10.1089/vbz.2019.2576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Japanese encephalitis virus (JEV) and West Nile virus (WNV) are arboviruses primarily transmitted by Culex spp. mosquitoes. Birds are the primary hosts for JEV and WNV. Recent WNV outbreaks in Europe and United States and their association with migratory birds highlight the importance of understanding the feeding host preference of potential vectors for outbreak preparedness, especially in nonendemic settings. Singapore is nonendemic to JEV and WNV, but is a stopover site for migratory birds of the East Asian-Australasian Flyway. Therefore, we elucidated the feeding host range of Culex spp. mosquitoes captured in four natural (bird) habitats in Singapore from January 2011 to December 2012. We characterized feeding host DNA in field-caught mosquitoes using a PCR sequencing-based assay targeting the mitochondrial gene regions. Of 22,648 mosquitoes captured, 21,287 belonged to the Culex vishnui subgroup. The host DNA analysis showed that mosquitoes from the Cx. vishnui subgroup are opportunistic biters, feeding on a range of birds and mammals. Cx. vishnui subgroup, Culex sitiens and Culex bitaeniorhynchus, was primarily ornithophagic, although they fed opportunistically on mammals, including humans. Culex gelidus and Culex quinquefasciatus, in contrast, fed mainly on mammals. The presence of ornitho- and anthropophilic mosquito vectors and susceptible avian and mammalian hosts poses a risk spill-over transmission of JEV and WNV among humans, should these viruses be introduced through migratory birds and establish persistent transmission in resident birds and animal hosts in Singapore.
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Affiliation(s)
- Gladys Yeo
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Sharon Chan
- Sungei Buloh Wetlands Reserve, National Parks Board, Singapore, Singapore
| | - Choon Beng How
- Sungei Buloh Wetlands Reserve, National Parks Board, Singapore, Singapore
| | - Mahathir Humaidi
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Xiao Fang Lim
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Diyar Mailepessov
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Chee Seng Chong
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Sai Gek Phua-Lam
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Ruth Lee
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | | | - Lee Ching Ng
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Grace Yap
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
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Yap G, Lim XF, Chan S, How CB, Humaidi M, Yeo G, Mailepessov D, Kong M, Lai YL, Okumura C, Ng LC. Serological evidence of continued Japanese encephalitis virus transmission in Singapore nearly three decades after end of pig farming. Parasit Vectors 2019; 12:244. [PMID: 31101069 PMCID: PMC6525359 DOI: 10.1186/s13071-019-3501-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 05/09/2019] [Indexed: 11/10/2022] Open
Abstract
Background Singapore used to report an annual average of 14 cases of Japanese encephalitis, but ever since the abolishment of pig farms in the early 1990s, the local incidence rate for Japanese encephalitis virus (JEV) infections has reduced drastically. Studies done in the early 2000s demonstrated the presence of JEV-specific antibodies in animals such as wild boars, dogs, chickens and goats on the offshore island and peripheral parts of the Singapore, indicative of prior JEV exposure. A JEV wildlife and sentinel chicken surveillance system was initiated in 2010 through to 2017 to study the animal host seroprofiles. Results A total of 12/371 (3.23%) of resident bird samples, 24/254 (9.45%) of migratory bird samples and 10/66 (15.16%) of wild boar samples were positive for the presence of JEV antibodies. Seroconversions in sentinel chickens were observed at two time points. Through this study, two sites with active transmission of JEV amongst avian or porcine hosts were identified. Conclusions JEV transmission in animal hosts has continued despite the phasing out of pig farming nearly thirty years ago; however, the public health risk of transmission remains low. Environmental management for mosquito population remains key to keeping this risk low.
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Affiliation(s)
- Grace Yap
- Environmental Health Institute, National Environment Agency, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Xiao Fang Lim
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | | | | | - Mahathir Humaidi
- Environmental Health Institute, National Environment Agency, Singapore, Singapore.
| | - Gladys Yeo
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Diyar Mailepessov
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Marcella Kong
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Yee Ling Lai
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | | | - Lee Ching Ng
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
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Lam-Phua SG, Yeo H, Lee RML, Chong CS, Png AB, Foo SY, Liew C, Ng LC, Tang CS, Rueda LM, Pecor JE, Harrison BA. Mosquitoes (Diptera: Culicidae) of Singapore: Updated Checklist and New Records. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:103-119. [PMID: 30169704 PMCID: PMC6324193 DOI: 10.1093/jme/tjy154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Indexed: 05/16/2023]
Abstract
Prior to 1965, Singapore was part of the Malaya (now Malaysia) and was usually not mentioned when mosquito records were reported for Malaya. Consequently, many species that occurred in Singapore were not listed in the world mosquito catalog, and the available checklist for Singapore since 1986 is incomplete, with some imprecise species information. In updating this checklist, we examined and verified mosquito specimens collected from Singapore in various depositories, including a thorough review of past taxonomic literature. Here, we report a checklist of 182 mosquito species, 33 new distribution records, and a consolidated status list of vectors for Singapore. As Singapore is a travel hub and hosts one of the busiest container ports in the world, there is a risk of introducing mosquito species and their associated pathogens of human disease to the country. Hence, the distribution records are important to increase our knowledge on mosquito ecology as well as to understand the risk of newly introduced vectors and their associated pathogens.
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Affiliation(s)
- Sai-Gek Lam-Phua
- Environmental Health Institute, National Environment Agency, Singapore
| | - Huiqing Yeo
- Environmental Health Institute, National Environment Agency, Singapore
| | - Ruth Mee-Lian Lee
- Environmental Health Institute, National Environment Agency, Singapore
| | - Chee-Seng Chong
- Environmental Health Institute, National Environment Agency, Singapore
| | - Ah-Bah Png
- Environmental Health Institute, National Environment Agency, Singapore
| | - Siew-Yoong Foo
- Environmental Health Institute, National Environment Agency, Singapore
| | - Christina Liew
- Environmental Health Institute, National Environment Agency, Singapore
| | - Lee-Ching Ng
- Environmental Health Institute, National Environment Agency, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Choon-Siang Tang
- Environmental Public Health Operations, National Environment Agency, Singapore
| | - Leopoldo M Rueda
- Department of Entomology, Walter Reed Biosystematics Unit, Smithsonian Institution, Museum Support Center (MRC534), Suitland, MD
| | - James E Pecor
- Department of Entomology, Walter Reed Biosystematics Unit, Smithsonian Institution, Museum Support Center (MRC534), Suitland, MD
| | - Bruce A Harrison
- Department of Entomology, Walter Reed Biosystematics Unit, Smithsonian Institution, Museum Support Center (MRC534), Suitland, MD
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Affiliation(s)
- Deborah H. L. Ng
- Department of Infectious Diseases, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore
- * E-mail: (DHLN); (SPS)
| | - Sapna P. Sadarangani
- Department of Infectious Diseases, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- * E-mail: (DHLN); (SPS)
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Low SL, Lam S, Wong WY, Teo D, Ng LC, Tan LK. Dengue seroprevalence of healthy adults in Singapore: serosurvey among blood donors, 2009. Am J Trop Med Hyg 2015; 93:40-45. [PMID: 26013376 PMCID: PMC4497902 DOI: 10.4269/ajtmh.14-0671] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 03/24/2015] [Indexed: 11/15/2022] Open
Abstract
Routine national notifications of dengue cases typically do not reflect the true dengue situation due to large proportion of unreported cases. Serosurveys, when conducted periodically, could shed light on the true dengue infections in the population. To determine the magnitude of dengue infections of the adult population in Singapore following the outbreak in 2007, we performed a cross-sectional study on blood donor samples from December 2009 to February 2010. The residual blood of 3,995 donors (aged 16–60 years) was screened for the presence of dengue-specific immunoglobulin G (IgG) and IgM using enzyme-linked immunosorbent assay (ELISA) kits. The age-weighted IgG prevalence of residents was 50.8% (N = 3,627, 95% confidence interval [CI] = 49.4–52.3%). Dengue IgG prevalence increased with age, with the lowest in 16–20 years age group (16.1%) and the highest in 56–60 years age group (86.6%). Plaque reduction neutralization test (PRNT) on samples of young resident adults (aged 16–30 years) revealed lower prevalence of neutralizing antibodies to each serotype, ranging from 5.4% to 20.3% compared with the older age groups. The level of exposure to dengue among the young adults is relatively low despite the endemicity of the disease in Singapore. It partially explains the population’s susceptibility to explosive outbreaks and the high incidence rate among young adults.
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Affiliation(s)
| | | | | | | | - Lee-Ching Ng
- *Address correspondence to Lee-Ching Ng, Environmental Health Institute, National Environment Agency, 11 Biopolis Way, No. 06-05/08 Helios Block, Singapore 138667. E-mail:
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Wang H, Liang G. Epidemiology of Japanese encephalitis: past, present, and future prospects. Ther Clin Risk Manag 2015; 11:435-48. [PMID: 25848290 PMCID: PMC4373597 DOI: 10.2147/tcrm.s51168] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Japanese encephalitis (JE) is one of severe viral encephalitis that affects individuals in Asia, western Pacific countries, and northern Australia. Although 67,900 JE cases have been estimated among 24 JE epidemic countries annually, only 10,426 have been reported in 2011. With the establishment of JE surveillance and vaccine use in some countries, the JE incidence rate has decreased; however, serious outbreaks still occur. Understanding JE epidemics and identifying the circulating JE virus genotypes will improve JE prevention and control. This review summarizes the current epidemiology data in these countries.
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Affiliation(s)
- Huanyu Wang
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing People's Republic of China ; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China
| | - Guodong Liang
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing People's Republic of China ; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China
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Lee DW, Choe YJ, Kim JH, Song KM, Cho H, Bae GR, Lee JK. Epidemiology of Japanese encephalitis in South Korea, 2007-2010. Int J Infect Dis 2012; 16:e448-52. [PMID: 22497964 DOI: 10.1016/j.ijid.2012.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 02/02/2012] [Indexed: 10/28/2022] Open
Abstract
BACKGROUND Japanese encephalitis (JE) was the leading cause of viral encephalitis among children in South Korea in the 20(th) century. This study summarizes recent changes in the epidemiology of JE following the implementation of a vigorous immunization program in the country. METHODS Epidemiological investigations were performed for all reported laboratory-confirmed JE cases, and the cumulative incidence was calculated for the surveillance years 2007-2010. RESULTS During the surveillance period, 45 cases of JE were confirmed in the country, resulting in a cumulative incidence of 0.013-0.055 cases per 100 000 population. The median age of cases was 49.4 years, and by age group, 44.4% were aged 40-49 years. Just under a quarter (22.2%) of the cases were found to live close to a pigsty, while 42.2% of the cases were found to reside in the metropolitan areas of Seoul, Incheon, and Gyeonggi-do. None of the cases had a history of vaccination. CONCLUSIONS Although JE has traditionally been regarded as a children's disease, the majority of cases now occur in adults in countries where strong immunization programs exist, such as in South Korea. Consideration should be given to an adult vaccination policy in the near future.
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Affiliation(s)
- Dong-Woo Lee
- Division of Vaccine Preventable Disease Control and National Immunization Program, Korea Centers for Disease Control and Prevention, Osong Health Technology Administration Complex, Gangoe-myon, Cheongwon-gun, Chungcheongbuk-do, Republic of Korea
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A new inactivated Japanese encephalitis vaccine for adult travelers. Travel Med Infect Dis 2009; 7:301-4. [PMID: 19747666 DOI: 10.1016/j.tmaid.2009.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 03/25/2009] [Indexed: 11/23/2022]
Abstract
Current guidelines for Japanese encephalitis (JE) vaccine relate to an older mouse brain derived vaccine with an uncertain history of adverse events including delayed anaphylaxis. JE is widely distributed, including in urban areas. Underreporting is likely in many endemic countries, and atypical clinical forms exist. A new JE vaccine produced in Vero cells has become available, which appears equi-efficacious to the mouse brain derived vaccine. In development trials the new JE vaccine was as well tolerated as placebo. A review of existing guidelines for JE vaccine use in travelers should be considered.
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Biswas SM, Ayachit VM, Sapkal GN, Mahamuni SA, Gore MM. Japanese encephalitis virus produces a CD4+ Th2 response and associated immunoprotection in an adoptive-transfer murine model. J Gen Virol 2009; 90:818-826. [DOI: 10.1099/vir.0.008045-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Japanese encephalitis is an acute infection of the central nervous system caused by Japanese encephalitis virus (JEV). The importance of an effective humoral response in preventing JEV infection has already been established, although the contribution of cellular immunity remains unclear. This study used an experimental murine model to understand the protective effects of cell-mediated immunity in JEV infection. Fourteen-day-old mice adoptively transferred with JEV-immune splenocytes were found to be protected from peripheral JEV challenge. The survival rate was reduced when transferred cells were depleted of their CD4+ T-cell population. Correspondingly, increased protection was observed when JEV-primed isolated CD4+ T cells were transferred compared with isolated CD8+ T cells. Mice protected from JEV infection by the adoptive transfer of JEV-immune splenocytes had higher levels of immunomodulatory cytokines and decreased expression of pro-inflammatory cytokines. Concurrent with the increase in Th2 cytokines, JEV-specific IgM and IgG1 antibody titres were found to be elevated in protected mice. Taken together, these data indicate a definite role for CD4+ T cells in protection from lethal JEV infection in naïve 14-day-old mice. Induction of a Th2 cytokine response and IgG1 antibody probably achieves an immunomodulatory effect that results in the enhanced survival of these animals.
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Affiliation(s)
- S. M. Biswas
- National Institute of Virology, Sus Road Campus, Pashan, Pune 411021, Maharashtra, India
| | - V. M. Ayachit
- National Institute of Virology, Sus Road Campus, Pashan, Pune 411021, Maharashtra, India
| | - G. N. Sapkal
- National Institute of Virology, Sus Road Campus, Pashan, Pune 411021, Maharashtra, India
| | - S. A. Mahamuni
- National Institute of Virology, Sus Road Campus, Pashan, Pune 411021, Maharashtra, India
| | - M. M. Gore
- National Institute of Virology, Sus Road Campus, Pashan, Pune 411021, Maharashtra, India
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Arya SC, Agarwal N. Re: Natural infection with Japanese encephalitis virus among inhabitants of Japan: a nationwide survey of antibodies against nonstructural 1 protein. Vaccine 2006; 24:5108-9. [PMID: 16713036 DOI: 10.1016/j.vaccine.2006.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2006] [Accepted: 04/06/2006] [Indexed: 11/24/2022]
Abstract
Investigations to assess episodes of any natural Japanese encephalitis (JE) infection following prior immunizations with JE inactivated vaccine in Japan are commendable. Employing differential production of nonstructural 1 protein NS1, during a natural infection and not by inactivated JE vaccine [Konishi E, Shoda M, Yamamoto S, Arai S, Tanaka-Taya K, Okabe N. Natural infection with Japanese encephalitis virus among inhabitants of Japan: a nationwide survey of antibodies against nonstructural 1 protein. Vaccine 2006;24:3054-956], natural infection was manifest in eight selected prefectures in Japan. Moreover, it would be possible to detect any foreign pathogenic JE virus (JEV) or any native strains associated with any major shift in JE clinical presentations. On the opposite, any NS1 antibody screen might be invalid among recipients of live JE vaccines.
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Mackenzie JS, Williams DT, Smith DW. Japanese Encephalitis Virus: The Geographic Distribution, Incidence, and Spread of a Virus with a Propensity to Emerge in New Areas. PERSPECTIVES IN MEDICAL VIROLOGY 2006. [DOI: 10.1016/s0168-7069(06)16010-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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