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Journal of Virology May 2024Live-attenuated flavivirus vaccines confer long-term protection against disease, but the design of attenuated flaviviruses does not follow a general approach. The... (Review)
Review
Live-attenuated flavivirus vaccines confer long-term protection against disease, but the design of attenuated flaviviruses does not follow a general approach. The non-coding, subgenomic flavivirus RNA (sfRNA) is produced by all flaviviruses and is an essential factor in viral pathogenesis and transmission. We argue that modulating sfRNA expression is a promising, universal strategy to finetune flavivirus attenuation for developing effective flavivirus vaccines of the future.
PubMed: 38808973
DOI: 10.1128/jvi.00100-23 -
Emerging Microbes & Infections Dec 2024Japanese encephalitis (JE), caused by the Japanese encephalitis virus (JEV) infection, continues to pose significant public health challenges worldwide despite efficient...
Japanese encephalitis (JE), caused by the Japanese encephalitis virus (JEV) infection, continues to pose significant public health challenges worldwide despite efficient vaccines. The virus is classified into five genotypes, among which genotype V (GV) was not detected for a long period after its initial isolation in 1952, until reports emerged from China and the Republic of Korea (ROK) since 2009. The characteristics of the virus are crucial in estimating its potential epidemiological impact. However, characterization of GV JEVs has so far been limited to two strains: Muar, the original isolate, and XZ0934, isolated in China. Two additional ROK GV JEV isolates, NCCP 43279 and NCCP 43413, are currently available, but their characteristics have not been explored. Our phylogenetic analysis revealed that GV virus sequences from the ROK segregate into two clades. NCCP 43279 and NCCP 43413 belong to different clades and exhibit distinct phenotypes. NCCP 43279 forms larger plaques but demonstrates inefficient propagation in cell culture compared to NCCP 43413. , NCCP 43279 induces higher morbidity and mortality in mice than NCCP 43413. Notably, NCCP 43279 shows more severe blood-brain barrier damage, suggesting superior brain invasion capabilities. Consistent with its higher virulence, NCCP 43279 displays more pronounced histopathological and immunopathological outcomes. In conclusion, our study confirms that the two ROK isolates are not only classified into different clades but also exhibit distinct and characteristics.
Topics: Encephalitis Virus, Japanese; Animals; Republic of Korea; Encephalitis, Japanese; Phylogeny; Genotype; Mice; Humans; Virulence; Cell Line; Female
PubMed: 38808613
DOI: 10.1080/22221751.2024.2362392 -
Wellcome Open Research 2024is an invasive mosquito species with an extensive and expanding inter-continental distribution, currently reported across Asia, Africa, the Middle East, Europe and now...
BACKGROUND
is an invasive mosquito species with an extensive and expanding inter-continental distribution, currently reported across Asia, Africa, the Middle East, Europe and now Australia. It is an important vector of medical and veterinary pathogens which cause significant morbidity and mortality in human and animal populations. Across regions endemic for Japanese encephalitis virus (JEV), is considered the major vector and has also been shown to contribute to the transmission of several other zoonotic arboviruses including Rift Valley fever virus (RVFV) and West Nile virus (WNV).
METHODS
In this study, we used laboratory vector competence experiments to determine if from a Southern European population were competent JEV vectors. We also obtained samples from multiple geographically dispersed populations from countries within Europe, Africa, Eurasia and Asia to perform phylogenetic analysis to measure the level of mitochondrial divergence using the ( ) gene. We also undertook bacterial gene amplicon sequencing to determine microbial diversity and used multi-locus sequence typing (MLST) to determine any evidence for the presence of strains of the naturally occurring endosymbiotic bacterium .
RESULTS
from a Greek population were shown be be competent vectors of JEV with high levels of virus present in saliva. We found a signficant level of mitochondrial genetic diversity using the mosquito gene between geographically dispersed populations. Furthermore, we report diverse microbiomes identified by gene amplicon sequencing within and between geographical populations. Evidence for the detection of the endosymbiotic bacteria was confirmed using -specific PCR and MLST.
CONCLUSIONS
This study enhances our understanding of the diversity of and the associated microbiome across its inter-continental range and highlights the need for greater surveillance of this invasive vector species in Europe.
PubMed: 38800519
DOI: 10.12688/wellcomeopenres.20761.1 -
Viruses May 2024The West Nile Virus (WNV), a member of the family , is an emerging mosquito-borne flavivirus causing potentially severe infections in humans and animals involving the... (Comparative Study)
Comparative Study
The West Nile Virus (WNV), a member of the family , is an emerging mosquito-borne flavivirus causing potentially severe infections in humans and animals involving the central nervous system (CNS). Due to its emerging tendency, WNV now occurs in many areas where other flaviviruses are co-occurring. Cross-reactive antibodies with flavivirus infections or vaccination (e.g., tick-borne encephalitis virus (TBEV), Usutu virus (USUV), yellow fever virus (YFV), dengue virus (DENV), Japanese encephalitis virus (JEV)) therefore remain a major challenge in diagnosing flavivirus infections. Virus neutralization tests are considered as reference tests for the detection of specific flavivirus antibodies, but are elaborate, time-consuming and need biosafety level 3 facilities. A simple and straightforward assay for the differentiation and detection of specific WNV IgG antibodies for the routine laboratory is urgently needed. In this study, we compared two commercially available enzyme-linked immunosorbent assays (anti-IgG WNV ELISA and anti-NS1-IgG WNV), a commercially available indirect immunofluorescence assay, and a newly developed in-house ELISA for the detection of WNV-NS1-IgG antibodies. All four tests were compared to an in-house NT to determine both the sensitivity and specificity of the four test systems. None of the assays could match the specificity of the NT, although the two NS1-IgG based ELISAs were very close to the specificity of the NT at 97.3% and 94.6%. The in-house WNV-NS1-IgG ELISA had the best performance regarding sensitivity and specificity. The specificities of the ELISA assays and the indirect immunofluorescence assays could not meet the necessary specificity and/or sensitivity.
Topics: West Nile virus; Antibodies, Viral; Humans; West Nile Fever; Sensitivity and Specificity; Enzyme-Linked Immunosorbent Assay; Serologic Tests; Immunoglobulin G; Fluorescent Antibody Technique, Indirect; Cross Reactions; Animals
PubMed: 38793670
DOI: 10.3390/v16050788 -
Viruses Apr 2024Yunnan province in China shares its borders with three neighboring countries: Myanmar, Vietnam, and Laos. The region is characterized by a diverse climate and is known...
Yunnan province in China shares its borders with three neighboring countries: Myanmar, Vietnam, and Laos. The region is characterized by a diverse climate and is known to be a suitable habitat for various arthropods, including midges which are notorious for transmitting diseases which pose significant health burdens affecting both human and animal health. A total of 431,100 midges were collected from 15 different locations in the border region of Yunnan province from 2015 to 2020. These midges were divided into 37 groups according to the collection year and sampling site. These 37 groups of midges were then homogenized to extract nucleic acid. Metatranscriptomics were used to analyze their viromes. Based on the obtained cytochrome C oxidase I gene (COI) sequences, three genera were identified, including one species of , one species of and twenty-five species of . We identified a total of 3199 viruses in five orders and 12 families, including 1305 single-stranded positive-stranded RNA viruses (+ssRNA) in two orders and seven families, 175 single-stranded negative-stranded RNA viruses (-ssRNA) in two orders and one family, and 1719 double-stranded RNA viruses in five families. Six arboviruses of economic importance were identified, namely Banna virus (BAV), Japanese encephalitis virus (JEV), Akabane virus (AKV), Bluetongue virus (BTV), Tibetan circovirus (TIBOV), and Epizootic hemorrhagic disease virus (EHDV), all of which are capable, to varying extents, of causing disease in humans and/or animals. The survey sites in this study basically covered the current distribution area of midges in Yunnan province, which helps to predict the geographic expansion of midge species. The complexity and diversity of the viral spectrum carried by midges identified in the study calls for more in-depth research, which can be utilized to monitor arthropod vectors and to predict the emergence and spread of zoonoses and animal epidemics, which is of great significance for the control of vector-borne diseases.
Topics: Animals; China; Phylogeny; Ceratopogonidae; RNA Viruses; Transcriptome; Insect Vectors; Virome; Humans
PubMed: 38793556
DOI: 10.3390/v16050674 -
Micromachines May 2024Chikungunya virus, a mosquito-borne virus that causes epidemics, is often misdiagnosed due to symptom similarities with other arboviruses. Here, a portable and...
Chikungunya virus, a mosquito-borne virus that causes epidemics, is often misdiagnosed due to symptom similarities with other arboviruses. Here, a portable and integrated nucleic acid-based diagnostic device, which combines reverse transcription-loop-mediated isothermal amplification and lateral-flow detection, was developed. The device is simple to use, precise, equipment-free, and highly sensitive, enabling rapid chikungunya virus identification. The result can be obtained by the naked eye within 40 min. The assay can effectively distinguish chikungunya virus from dengue virus, Japanese encephalitis virus, Zika virus, and yellow fever virus with high specificity and sensitivity as low as 598.46 copies mL. It has many benefits for the community screening and monitoring of chikungunya virus in resource-limited areas because of its effectiveness and simplicity. The platform has great potential for the rapid nucleic acid detection of other viruses.
PubMed: 38793236
DOI: 10.3390/mi15050663 -
Veterinary Sciences May 2024The Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, has a wide host range, extending from pigs and ardeid birds to opportunistic dead-end hosts, such as...
The Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, has a wide host range, extending from pigs and ardeid birds to opportunistic dead-end hosts, such as humans and horses. However, JEV encephalitis infections in aquatic mammals are rare, with only two cases in seals reported to date. Here, we report a lethal case of JEV and co-infection in an aquarium-housed harbor seal in Japan. We isolated JEV from the brain of the dead seal and characterized its phylogeny and pathogenicity in mice. The virus isolate from the seal was classified as genotype GIb, which aligns with recent Japanese human and mosquito isolates as well as other seal viruses detected in China and Korea, and does not exhibit a unique sequence trait distinct from that of human and mosquito strains. We demonstrated that the seal isolate is pathogenic to mice and causes neuronal symptoms. These data suggest that seals should be considered a susceptible dead-end host for circulating JEV in natural settings.
PubMed: 38787188
DOI: 10.3390/vetsci11050215 -
Tropical Medicine and Infectious Disease May 2024Japanese encephalitis virus (JEV) has a positive-sense single-stranded RNA genome and belongs to the genus of the family . Persistent JEV infection was previously shown...
Japanese encephalitis virus (JEV) has a positive-sense single-stranded RNA genome and belongs to the genus of the family . Persistent JEV infection was previously shown in pig blood cells, which act as a natural reservoir of this virus. We aimed to determine the pathogenicity factors involved in persistent JEV infection by analyzing the pathogenicity and genome sequences of a virus isolated from a persistent infection model. We established persistent JEV infections in cells by inoculating mouse fetus primary cell cultures with the Beijing-1 strain of JEV and then performing repeated infected cell passages, harvesting viruses after each passage while monitoring the plaque size over 100 generations. The virus growth rate was compared among Vero, C6/36, and Neuro-2a cells. The pathogenicity was examined in female ICR mice at several ages. Additionally, we determined the whole-genome sequences. The 134th Beijing-1-derived persistent virus (ME134) grew in Vero cells at a similar rate to the parent strain but did not grow well in C6/36 or Neuro-2a cells. No differences were observed in pathogenicity after intracerebral inoculation in mice of different ages, but the survival time was extended in older mice. Mutations in the persistent virus genomes were found across all regions but were mainly focused in the NS3, NS4b, and 3'NCR regions, with a 34-base-pair deletion found in the variable region. The short deletion in the 3'NCR region appeared to be responsible for the reduced pathogenicity and growth efficiency.
PubMed: 38787050
DOI: 10.3390/tropicalmed9050117 -
Veterinaria Italiana Dec 2023Japanese encephalitis virus (JEV) is a zoonotic arbovirus that causes abortion, stillbirth, and congenital defects in pigs, and epidemic encephalitis in humans....
Japanese encephalitis virus (JEV) is a zoonotic arbovirus that causes abortion, stillbirth, and congenital defects in pigs, and epidemic encephalitis in humans. Currently, there is scarcity of information on JEV infection in pigs in Nigeria. Since the Culex tritaeniorhynchus vector of JEV is present in Nigeria and considering recent anecdotal reports of abortions and birth of weak piglets in some pig farms in southwestern Nigeria, there is a need for studies on the presence of the virus and its true burden among pig populations in the country. Serum samples (n=368) obtained from farm-reared pigs in four States of southwestern Nigeria were screened for JEV-specific IgG antibodies using a commercial ELISA kit. An overall JEV seropositivity of 35.1% (95% CI: 30.18 - 39.93%) was obtained, with detectable antibodies in pigs of all age groups, breeds, sex, and locations. Our results suggest natural exposure of these unvaccinated intensively reared pigs to JEV circulating silently in the swine population with significant association of the seropositivity with location (state/community in which the pig farms exist) and breed of the pigs studied. This first report of detection of anti-JEV antibodies in pigs in Nigeria indicates that JEV circulated among these pigs and underscores the need for active surveillance for JEV in humans, pigs, and mosquitoes to provide valuable epidemiological data for the design of effective control strategies against the virus, thus forestalling potential future outbreaks of the infection.
Topics: Animals; Nigeria; Swine; Encephalitis Virus, Japanese; Encephalitis, Japanese; Swine Diseases; Female; Seroepidemiologic Studies; Male; Antibodies, Viral
PubMed: 38756025
DOI: 10.12834/VetIt.3021.20221.2 -
Emerging Microbes & Infections Dec 2024Reverse genetic systems are mainly used to rescue recombinant viral strains in cell culture. These tools have also been used to generate, by inoculating infectious...
Reverse genetic systems are mainly used to rescue recombinant viral strains in cell culture. These tools have also been used to generate, by inoculating infectious clones, viral strains directly in living animals. We previously developed the "Infectious Subgenomic Amplicons" (ISA) method, which enables the rescue of single-stranded positive sense RNA viruses by transfecting overlapping subgenomic DNA fragments. Here, we provide proof-of-concept for direct generation of infectious particles following the inoculation of subgenomic amplicons. First, we rescued a strain of tick-borne encephalitis virus in mice to transpose the ISA method . Subgenomic DNA fragments were amplified using a 3-fragment reverse genetics system and inoculated intramuscularly. Almost all animals were infected when quantities of DNA inoculated were at least 20 µg. We then optimized our procedure in order to increase the animal infection rate. This was achieved by adding an electroporation step and/or using a simplified 2- fragment reverse genetics system. Under optimal conditions, a large majority of animals were infected with doses of 20 ng of DNA. Finally, we demonstrated the versatility of this method by applying it to Japanese encephalitis and Chikungunya viruses. This method provides an efficient strategy for rescue of arboviruses. Furthermore, in the context of the development of DNA-launched live attenuated vaccines, this new approach may facilitate the generation of attenuated strains . It also enables to deliver a substance free of any vector DNA, which seems to be an important criterion for the development of human vaccines.
Topics: Animals; Mice; Encephalitis Viruses, Tick-Borne; Reverse Genetics; Arboviruses; Chikungunya virus; Encephalitis Virus, Japanese; DNA, Viral; Encephalitis, Tick-Borne; Female; Genome, Viral; Chikungunya Fever; Humans
PubMed: 38742328
DOI: 10.1080/22221751.2024.2356140