Japanese Encephalitis Virus

A special issue of Viruses (ISSN 1999-4915). This special issue belongs to the section "General Virology".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 15452

Special Issue Editors


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Guest Editor
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China
Interests: mosquito-borne viruses; innate immunity; host factors; virus replication; pathogenesis; antiviral response and vaccines

E-Mail Website
Guest Editor
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China
Interests: flaviviruses; viral pathogenesis; viral genetics and evolution; cross-species transmission; molecular diagnostics; viral metagenomics; vaccine and antiviral development

Special Issue Information

Dear Colleagues,

Japanese encephalitis virus (JEV) is the pathogen causing Japanese encephalitis (JE), which is mainly transmitted in Nature through mosquito bites. JEV can cause central nervous system damage in humans and reproductive disorders in pigs, posing a serious threat to public health. JEV is widely distributed in Asia and Western Pacific regions, causing an estimated 57,000 to 175,000 cases annually. It has a 20–30% case fatality rate, and approximately 30%–50% of survivors suffer from severe neurological sequelae. JEV is classified into five genotypes (I, II, III, IV, and V). In recent years there have been some new changes in the epidemic of Japanese encephalitis, including the expansion of the epidemic area and the displacement of dominant genotypes: the dominant genotype of the virus gradually shifted from genotype III to genotype I (GI), and the epidemic area of genotype V (GV) JEV may be increasing, which seriously threatens the public safety of human beings and the healthy development of animal husbandry, bringing new challenges in disease prevention and control.

This Special Issue will cover the recent developments in Japanese encephalitis virus, including epidemiology, pathogenesis, diagnostics, virulence, transmission, virus evolution, genotype shift, mechanisms of virus-host-cell interaction, animal models for reservoirs, immune response, vector and biological control, and new approaches to the vaccine and antivirals of the disease. Different manuscript forms, including original research papers, short communications, and reviews, are all welcome in this Special Issue.

Prof. Dr. Zhiyong Ma
Dr. Jianchao Wei
Guest Editors

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Keywords

  • epidemiology
  • pathogenesis
  • diagnostics
  • virulence
  • transmission
  • virus evolution
  • genotype shift
  • virus-host interaction
  • immune response
  • vector and biological control
  • vaccine and antivirals

Published Papers (6 papers)

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Research

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12 pages, 733 KiB  
Article
Genotype Change in Circulating JEV Strains in Fujian Province, China
by Nihua Dong, Xinya Zhang, Hailong Zhang, Jiayang Zheng, Yafeng Qiu, Zongjie Li, Beibei Li, Ke Liu, Donghua Shao, Zhiyong Ma and Jianchao Wei
Viruses 2023, 15(9), 1822; https://doi.org/10.3390/v15091822 - 26 Aug 2023
Cited by 1 | Viewed by 1009
Abstract
Japanese encephalitis (JE), found in pigs, is a serious mosquito-borne zoonotic infectious disease caused by the Japanese encephalitis virus (JEV). JEV is maintained in an enzootic cycle between mosquitoes and amplifying vertebrate hosts, mainly pigs and wading birds. It is transmitted to humans [...] Read more.
Japanese encephalitis (JE), found in pigs, is a serious mosquito-borne zoonotic infectious disease caused by the Japanese encephalitis virus (JEV). JEV is maintained in an enzootic cycle between mosquitoes and amplifying vertebrate hosts, mainly pigs and wading birds. It is transmitted to humans through the bite of an infected mosquito, allowing the pathogen to spread and cause disease epidemics. However, there is little research on JEV genotype variation in mosquitoes and pigs in Fujian province. Previous studies have shown that the main epidemic strain of JEV in Fujian Province is genotype III. In this study, a survey of mosquito species diversity in pig farms and molecular evolutionary analyses of JEV were conducted in Fujian, China, in the summer of 2019. A total of 19,177 mosquitoes were collected at four sites by UV trap. Four genera were identified, of which the Culex tritaeniorhynchus was the most common mosquito species, accounting for 76.4% of the total (14,651/19,177). Anopheles sinensi (19.25%, 3691/19,177) was the second largest species. High mosquito infection rateswere an important factor in the outbreak. The captured mosquito samples were milled and screened with JEV-specific primers. Five viruses were isolated, FJ1901, FJ1902, FJ1903, FJ1904, and FJ1905. Genetic affinity was determined by analyzing the envelope (E) gene variants. The results showed that they are JEV gene type I and most closely related to the strains SH-53 and SD0810. In this study, it was found through genetic evolution analysis that the main epidemic strain of JE in pig farms changed from gene type III to gene type I. Compared with the SH-53 and SD0810 strains, we found no change in key sites related to antigenic activity and neurovirulence of JEV in Fujian JEV and pig mosquito strains, respectively. The results of the study provide basic data for analyzing the genotypic shift of JEV in Fujian Province and support the prevention and control of JEV. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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21 pages, 25018 KiB  
Article
Re-Emerged Genotype IV of Japanese Encephalitis Virus Is the Youngest Virus in Evolution
by Guanlun Xu, Tingting Gao, Zhijie Wang, Jun Zhang, Baoqiu Cui, Xinxin Shen, Anyang Zhou, Yuan Zhang, Jie Zhao, Hong Liu and Guangdong Liang
Viruses 2023, 15(3), 626; https://doi.org/10.3390/v15030626 - 24 Feb 2023
Cited by 3 | Viewed by 1883
Abstract
An outbreak of viral encephalitis caused by a Japanese encephalitis virus (JEV) genotype IV infection occurred in Australia between 2021 and 2022. A total of 47 cases and seven deaths were reported as of November 2022. This is the first outbreak of human [...] Read more.
An outbreak of viral encephalitis caused by a Japanese encephalitis virus (JEV) genotype IV infection occurred in Australia between 2021 and 2022. A total of 47 cases and seven deaths were reported as of November 2022. This is the first outbreak of human viral encephalitis caused by JEV GIV since it was first isolated in Indonesia in the late 1970s. Here, a comprehensive phylogenetic analysis based on the whole genome sequences of JEVs revealed it emerged 1037 years ago (95% HPD: 463 to 2100 years). The evolutionary order of JEV genotypes is as follows: GV, GIII, GII, GI, and GIV. The JEV GIV emerged 122 years ago (95% HPD: 57–233) and is the youngest viral lineage. The mean substitution rate of the JEV GIV lineage was 1.145 × 10−3 (95% HPD values, 9.55 × 10−4, 1.35 × 10−3), belonging to rapidly evolving viruses. A series of amino acid mutations with the changes of physico-chemical properties located in the functional important domains within the core and E proteins distinguished emerging GIV isolates from old ones. These results demonstrate the JEV GIV is the youngest JEV genotype at a rapid evolution stage and has good host/vector adaptability for introduction to non-endemic areas. Thus, surveillance of JEVs is highly recommended. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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12 pages, 2192 KiB  
Article
Japanese Encephalitis Enzootic and Epidemic Risks across Australia
by Morgan Furlong, Andrew M. Adamu, Andrew Hoskins, Tanya L. Russell, Bruce Gummow, Maryam Golchin, Roslyn I. Hickson and Paul F. Horwood
Viruses 2023, 15(2), 450; https://doi.org/10.3390/v15020450 - 06 Feb 2023
Cited by 7 | Viewed by 3446
Abstract
Japanese encephalitis virus (JEV) is an arboviral, encephalitogenic, zoonotic flavivirus characterized by its complex epidemiology whose transmission cycle involves reservoir and amplifying hosts, competent vector species and optimal environmental conditions. Although typically endemic in Asia and parts of the Pacific Islands, unprecedented outbreaks [...] Read more.
Japanese encephalitis virus (JEV) is an arboviral, encephalitogenic, zoonotic flavivirus characterized by its complex epidemiology whose transmission cycle involves reservoir and amplifying hosts, competent vector species and optimal environmental conditions. Although typically endemic in Asia and parts of the Pacific Islands, unprecedented outbreaks in both humans and domestic pigs in southeastern Australia emphasize the virus’ expanding geographical range. To estimate areas at highest risk of JEV transmission in Australia, ecological niche models of vectors and waterbirds, a sample of piggery coordinates and feral pig population density models were combined using mathematical and geospatial mapping techniques. These results highlight that both coastal and inland regions across the continent are estimated to have varying risks of enzootic and/or epidemic JEV transmission. We recommend increased surveillance of waterbirds, feral pigs and mosquito populations in areas where domestic pigs and human populations are present. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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13 pages, 969 KiB  
Article
Growth, Pathogenesis, and Serological Characteristics of the Japanese Encephalitis Virus Genotype IV Recent Strain 19CxBa-83-Cv
by Shigeru Tajima, Takahiro Maeki, Eri Nakayama, Astri Nur Faizah, Daisuke Kobayashi, Haruhiko Isawa, Yoshihide Maekawa, Sri Subekti Bendryman, Kris Cahyo Mulyatno, Etik Ainun Rohmah, Yasuko Mori, Kyoko Sawabe, Hideki Ebihara and Chang-Kweng Lim
Viruses 2023, 15(1), 239; https://doi.org/10.3390/v15010239 - 14 Jan 2023
Cited by 1 | Viewed by 2068
Abstract
Genotype IV Japanese encephalitis (JE) virus (GIV JEV) is the least common and most neglected genotype in JEV. We evaluated the growth and pathogenic potential of the GIV strain 19CxBa-83-Cv, which was isolated from a mosquito pool in Bali, Indonesia, in 2019, and [...] Read more.
Genotype IV Japanese encephalitis (JE) virus (GIV JEV) is the least common and most neglected genotype in JEV. We evaluated the growth and pathogenic potential of the GIV strain 19CxBa-83-Cv, which was isolated from a mosquito pool in Bali, Indonesia, in 2019, and serological analyses were also conducted. The growth ability of 19CxBa-83-Cv in Vero cells was intermediate between that of the genotype I (GI) strain Mie/41/2002 and the genotype V (GV) strain Muar, whereas 19CxBa-83-Cv and Mie/41/2002 grew faster than Muar in mouse neuroblastoma cells. The neuroinvasiveness of 19CxBa-83-Cv in mice was higher than that of Mie/41/2002 but lower than that of Muar; however, there were no significant differences in neurovirulence in mice among the three strains. The neutralizing titers of sera from 19CxBa-83-Cv- and Mie/41/2002-inoculated mice against 19CxBa-83-Cv and Mie/41/2002 were similar, whereas the titers against Muar were lower than those of the other two viruses. The neutralizing titers of JE vaccine-inoculated mouse pool serum against 19CxBa-83-Cv and Muar were significantly lower than those against Mie/41/2002. The neutralizing titers against the three viruses were similar in three out of the five serum samples from GI-infected JE patients, although the titers against Mie/41/2002 were higher than those against 19CxBa-83-Cv and Muar in the remaining two sera samples. In summary, we identified the basic characteristics of 19CxBa-83-Cv, but further studies are needed to better understand GIV JEV. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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18 pages, 1348 KiB  
Article
Isolation and Genetic Characterization of Japanese Encephalitis Virus Two Decades after Its Elimination in Singapore
by Ming Jie Lim, Zhi Yang Loh, Hui Ling Yeo, Surya Pavan Yenamandra, Marcella Kong, Hao Yang Pang, Meng Han Lee, Mahathir Humaidi, Cliff Chua, Jane Griffiths, Lee Ching Ng, Hapuarachchige Chanditha Hapuarachchi and Diyar Mailepessov
Viruses 2022, 14(12), 2662; https://doi.org/10.3390/v14122662 - 28 Nov 2022
Cited by 2 | Viewed by 1805
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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Review

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26 pages, 2109 KiB  
Review
Japanese Encephalitis Virus: The Emergence of Genotype IV in Australia and Its Potential Endemicity
by John S. Mackenzie, David T. Williams, Andrew F. van den Hurk, David W. Smith and Bart J. Currie
Viruses 2022, 14(11), 2480; https://doi.org/10.3390/v14112480 - 09 Nov 2022
Cited by 23 | Viewed by 4492
Abstract
A fatal case of Japanese encephalitis (JE) occurred in northern Australia in early 2021. Sequence studies showed that the virus belonged to genotype IV (GIV), a genotype previously believed to be restricted to the Indonesian archipelago. This was the first locally acquired case [...] Read more.
A fatal case of Japanese encephalitis (JE) occurred in northern Australia in early 2021. Sequence studies showed that the virus belonged to genotype IV (GIV), a genotype previously believed to be restricted to the Indonesian archipelago. This was the first locally acquired case of Japanese encephalitis virus (JEV) GIV to occur outside Indonesia, and the second confirmed fatal human case caused by a GIV virus. A closely related GIV JEV strain subsequently caused a widespread outbreak in eastern Australia in 2022 that was first detected by fetal death and abnormalities in commercial piggeries. Forty-two human cases also occurred with seven fatalities. This has been the first major outbreak of JEV in mainland Australia, and geographically the largest virgin soil outbreak recorded for JEV. This outbreak provides an opportunity to discuss and document the factors involved in the virus’ spread and its ecology in a novel ecological milieu in which other flaviviruses, including members of the JE serological complex, also occur. The probable vertebrate hosts and mosquito vectors are discussed with respect to virus spread and its possible endemicity in Australia, and the need to develop a One Health approach to develop improved surveillance methods to rapidly detect future outbreak activity across a large geographical area containing a sparse human population. Understanding the spread of JEV in a novel ecological environment is relevant to the possible threat that JEV may pose in the future to other receptive geographic areas, such as the west coast of the United States, southern Europe or Africa. Full article
(This article belongs to the Special Issue Japanese Encephalitis Virus)
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