Displaying publications 1 - 20 of 33 in total

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  1. Fulltext Evidence of West Nile virus infection in migratory and resident wild birds in west coast of peninsular Malaysia
    Ain-Najwa MY, Yasmin AR, Omar AR, Arshad SS, Abu J, Mohammed HO, et al.
    One Health, 2020 Dec;10:100134.
    PMID: 32405525 DOI: 10.1016/j.onehlt.2020.100134
    West Nile virus (WNV) is a zoonotic mosquito-borne flavivirus that is harbored and amplified by wild birds via the enzootic transmission cycle. Wide range of hosts are found to be susceptible to WNV infection including mammals, amphibians and reptiles across the world. Several studies have demonstrated that WNV was present in the Malaysian Orang Asli and captive birds. However, no data are available on the WNV prevalence in wild birds found in Malaysia. Therefore this study was conducted to determine the serological and molecular prevalence of WNV in wild birds in selected areas in the West Coast of Peninsular Malaysia. Two types of wild birds were screened, namely migratory and resident birds in order to explore any possibility of WNV transmission from the migratory birds to the resident birds. Thus, a cross-sectional study was conducted at the migratory birds sanctuary located in Kuala Gula, Perak and Kapar, Selangor by catching 163 migratory birds, and 97 resident birds from Kuala Gula and Parit Buntar, Perak at different time between 2016 and 2017 (Total, n = 260). Blood and oropharyngeal swabs were collected for serological and molecular analysis, respectively. Serum were screened for WNV antibodies using a commercial competitive ELISA (c-ELISA) (ID Screen® West Nile Competition Multi-species ELISA, ID VET, Montpellier, France) and cross-reactivity towards Japanese Encephalitis virus (JEV) was also carried out using the JEV-double antigen sandwich (DAS) ELISA. Oropharyngeal swabs were subjected to one-step RT-PCR to detect WNV RNA, in which positive reactions were subsequently sequenced. WNV seropositive rate of 18.71% (29/155) at 95% CI (0.131 to 0.260) and molecular prevalence of 15.2% (16/105) at 95% CI (0.092 to 0.239) were demonstrated in migratory and resident wild birds found in West Coast Malaysia. Phylogenetic analyses of the 16 WNV isolates found in this study revealed that the local strains have 99% similarity to the strains from South Africa and were clustered under lineage 2. Evidence of WNV infection in resident and migratory birds were demonstrated in this study. As a summary, intervention between migratory birds, resident birds and mosquitoes might cause the introduction and maintenance of WNV in Malaysia, however the assumption could be further proven by studying the infection dynamics in the mosquitoes present in the studied areas.
    Matched MeSH terms: Flavivirus
  2. Fulltext Electrochemical biosensor detection on respiratory and flaviviruses
    Ang PC, Perumal V, Ibrahim MNM, Adnan R, Mohd Azman DK, Gopinath SCB, et al.
    Appl Microbiol Biotechnol, 2023 Mar;107(5-6):1503-1513.
    PMID: 36719432 DOI: 10.1007/s00253-023-12400-y
    Viruses have spread throughout the world and cause acute illness or death among millions of people. There is a growing concern about methods to control and combat early-stage viral infections to prevent the significant public health problem. However, conventional detection methods like polymerase chain reaction (PCR) requires sample purification and are time-consuming for further clinical diagnosis. Hence, establishing a portable device for rapid detection with enhanced sensitivity and selectivity for the specific virus to prevent further spread becomes an urgent need. Many research groups are focusing on the potential of the electrochemical sensor to become a key for developing point-of-care (POC) technologies for clinical analysis because it can solve most of the limitations of conventional diagnostic methods. Herein, this review discusses the current development of electrochemical sensors for the detection of respiratory virus infections and flaviviruses over the past 10 years. Trends in future perspectives in rapid clinical detection sensors on viruses are also discussed. KEY POINTS: • Respiratory related viruses and Flavivirus are being concerned for past decades. • Important to differentiate the cross-reactivity between the virus in same family. • Electrochemical biosensor as a suitable device to detect viruses with high performance.
    Matched MeSH terms: Flavivirus*
  3. A case of Japanese encephalitis
    Burdon JT, Stanley PJ, Lloyd G, Jones NC
    J Infect, 1994 Mar;28(2):175-9.
    PMID: 8034997
    We report a case of Japanese encephalitis that occurred in a woman who had spent only a few days in an area where she could have been exposed to the virus. The risks and protective efficacy of vaccination against Japanese encephalitis virus for travellers who visit endemic areas for only a short period are discussed.
    Matched MeSH terms: Flavivirus/immunology
  4. Antibodies against prM protein distinguish between previous infection with dengue and Japanese encephalitis viruses
    Cardosa MJ, Wang SM, Sum MS, Tio PH
    BMC Microbiol, 2002 May 5;2:9.
    PMID: 12019028
    In Southeast Asia, dengue viruses often co-circulate with other flaviviruses such as Japanese encephalitis virus, and due to the presence of shared antigenic epitopes it is often difficult to use serological methods to distinguish between previous infections by these flaviviruses.
    Matched MeSH terms: Flavivirus Infections/blood; Flavivirus Infections/diagnosis*
  5. Fulltext A systematic review: public health policies on Zika infection surveillance for Malaysia
    Chin Mun Wong, Rozita Hod, Mohd Rohaizat Hassan, Sazaly Abu Bakar
    Malaysian Journal of Medicine and Health Sciences, 2019;15(106):3-3.
    MyJurnal
    Introduction: Zika infection was declared as Public Health Emergency of International Concern since year 2015. Despite of no new reported case via National Surveillance System for flavivirus, an underestimated seroprevalence might occur as the country contributes to the Asian lineage of the virus. Methods: Systematic literature search using PICO framework and PRISMA checklist across four databases for articles published from year 2013-2018 yielded 189 results, 37 articles accepted by titles following criteria were subjected to abstract screening, leaving 8 articles with clear risk proceed to full text analysis using Cochrane checklist and GRADE assessment. Results: There were four high quality articles and four low quality articles based on biases in studies. Blood product management and vac-cination are strategies strongly recommended to be implemented as Zika response while vector control and family planning are public health measures to be proposed as policy if feasible. Successful factors to improve Zika surveil-lance and management includes developing algorithm for blood product management, anti-Zika vaccine research, algorithm for new-born screening, participation of policy makers, healthcare capacity building, raising healthcare and public awareness on the infection, international funding, utilization of technology in data management and bio-logical control of vector. Conclusion: Implementation of Zika response as policy is timely, should be evidence-based and follow guidelines from WHO / CDC / FDA US after cost-effectiveness evaluation for Malaysia setting.
    Matched MeSH terms: Flavivirus
  6. Flavivirus infection-A review of immunopathogenesis, immunological response, and immunodiagnosis
    Chong HY, Leow CY, Abdul Majeed AB, Leow CH
    Virus Res, 2019 12;274:197770.
    PMID: 31626874 DOI: 10.1016/j.virusres.2019.197770
    Flaviviruses are group of single stranded RNA viruses that cause severe endemic infection and epidemics on a global scale. It presents a significant health impact worldwide and the viruses have the potential to emerge and outbreak in a non-endemic geographical region. Effective vaccines for prophylaxis are only available for several flaviviruses such as Yellow Fever virus, Tick-borne Encephalitis Virus, Dengue Virus and Japanese Encephalitis Virus and there is no antiflaviviral agent being marketed. This review discusses the flavivirus genome, replication cycle, epidemiology, clinical presentation and pathogenesis upon infection. Effective humoral response is critical to confer protective immunity against flaviviruses. Hence, we have also highlighted the immune responses elicited upon infection, various diagnostic facilities available for flaviviral disease and monoclonal antibodies available to date against flavivirus infection.
    Matched MeSH terms: Flavivirus/genetics; Flavivirus/immunology*; Flavivirus/isolation & purification*; Flavivirus/physiology; Flavivirus Infections/diagnosis*; Flavivirus Infections/drug therapy; Flavivirus Infections/immunology*; Flavivirus Infections/pathology
  7. Diversity and evolution of the envelope gene of dengue virus type 1 circulating in India in recent times
    Dey S, Nandy A, Nandy P, Das S
    Int J Bioinform Res Appl, 2015;11(6):469-82.
    PMID: 26642358 DOI: 10.1504/ijbra.2015.073235
    Dengue viral attacks have been reported in various parts of India in recent years. In this paper we report on our studies of the characterisation and evolutionary aspects of gene sequences of the envelope glycoprotein of the prevalent Indian dengue virus type 1. Comparison with sequences from other countries shows that the envelope genes identified in India are closely related to strains from Malaysia. From the evolutionary point of view the envelope gene sequences of this dengue virus of India for past few years show that a marked mutational shift in the nucleotide sequences of the envelope gene have taken place from around the year 2000. Also, phylogenetic relationship with other three sera of dengue virus reported in India from 2005 shows that the dengue virus 1 is more closely related to dengue viruses 3 and 4 and relatively distantly to dengue virus 2.
    Matched MeSH terms: Flavivirus
  8. Attenuation of virulence of flaviviruses following passage in HeLa cells
    Dunster LM, Gibson CA, Stephenson JR, Minor PD, Barrett AD
    J Gen Virol, 1990 Mar;71 ( Pt 3):601-7.
    PMID: 2155996
    The ability of passage in HeLa cells to attenuate flaviviruses was investigated for three different strains of the mosquito-borne West Nile (WN) virus and two tick-borne viruses, louping-ill and Langat. One strain of WN virus, Sarawak, was attenuated 4000-fold for adult mice by intraperitoneal or intranasal challenge after six HeLa passages. The HeLa-passaged virus was also found to be antigenically different and temperature-sensitive in its growth characteristics compared with the parent. After six HeLa cell passages the Egypt 101 and Smithburn strains of WN virus lost their ability to infect monkey kidney cells and no longer killed adult mice, although inoculated animals became sick for several days. In contrast, two tick-borne flaviviruses remained as virulent for mice after six HeLa passages as the parent non-HeLa-passaged virus. Neither of the tick-borne viruses exhibited characteristics associated with temperature sensitivity. The results, therefore, indicate that the mosquito-borne, but not tick-borne, flaviviruses can be attenuated by very few passages in HeLa cells. This observation may provide a model system with which to analyse the molecular basis of attenuation and/or virulence of mosquito-borne flaviviruses.
    Matched MeSH terms: Flavivirus/growth & development; Flavivirus/pathogenicity*
  9. Fulltext Interaction between Flavivirus and Cytoskeleton during Virus Replication
    Foo KY, Chee HY
    Biomed Res Int, 2015;2015:427814.
    PMID: 26347881 DOI: 10.1155/2015/427814
    Flaviviruses are potentially human pathogens that cause major epidemics worldwide. Flavivirus interacts with host cell factors to form a favourable virus replication site. Cell cytoskeletons have been observed to have close contact with flaviviruses, which expands the understanding of cytoskeleton functions during virus replication, although many detailed mechanisms are still unclear. The interactions between the virus and host cytoskeletons such as actin filaments, microtubules, and intermediate filaments have provided insight into molecular alterations during the virus infection, such as viral entry, in-cell transport, scaffold assembly, and egress. This review article focuses on the utilization of cytoskeleton by Flavivirus and the respective functions during virus replication.
    Matched MeSH terms: Flavivirus/physiology*; Flavivirus Infections/metabolism*
  10. Fulltext Characterization of Three New Insect-Specific Flaviviruses: Their Relationship to the Mosquito-Borne Flavivirus Pathogens
    Guzman H, Contreras-Gutierrez MA, Travassos da Rosa APA, Nunes MRT, Cardoso JF, Popov VL, et al.
    Am J Trop Med Hyg, 2018 02;98(2):410-419.
    PMID: 29016330 DOI: 10.4269/ajtmh.17-0350
    Three novel insect-specific flaviviruses, isolated from mosquitoes collected in Peru, Malaysia (Sarawak), and the United States, are characterized. The new viruses, designated La Tina, Kampung Karu, and Long Pine Key, respectively, are antigenically and phylogenetically more similar to the mosquito-borne flavivirus pathogens, than to the classical insect-specific viruses like cell fusing agent and Culex flavivirus. The potential implications of this relationship and the possible uses of these and other arbovirus-related insect-specific flaviviruses are reviewed.
    Matched MeSH terms: Flavivirus/genetics; Flavivirus/pathogenicity
  11. Tembusu-like flavivirus (Perak virus) as the cause of neurological disease outbreaks in young Pekin ducks
    Homonnay ZG, Kovács EW, Bányai K, Albert M, Fehér E, Mató T, et al.
    Avian Pathol, 2014;43(6):552-60.
    PMID: 25299764 DOI: 10.1080/03079457.2014.973832
    A neurological disease of young Pekin ducks characterized by ataxia, lameness, and paralysis was observed at several duck farms in Malaysia in 2012. Gross pathological lesions were absent or inconsistent in most of the cases, but severe and consistent microscopic lesions were found in the brain and spinal cord, characterized by non-purulent panencephalomyelitis. Several virus isolates were obtained in embryonated duck eggs and in cell cultures (Vero and DF-1) inoculated with the brain homogenates of affected ducks. After exclusion of other viruses, the isolates were identified as a flavivirus by flavivirus-specific reverse transcription-polymerase chain reaction (RT-PCR) assays. Inoculation of 2-week-old Pekin ducks with a flavivirus isolate by the subcutaneous or intramuscular route resulted in typical clinical signs and histological lesions in the brain and spinal cord. The inoculated virus was detected by RT-PCR from organ samples of ducks with clinical signs and histological lesions. With a few days delay, the disease was also observed among co-mingled contact control birds. Phylogenetic analysis of NS5 and E gene sequences proved that the isolates were representatives of a novel phylogenetic group within clade XI (Ntaya virus group) of the Flavivirus genus. This Malaysian Duck Tembusu Virus (DTMUV), named Perak virus, has moderate genomic RNA sequence similarity to a related DTMUV identified in China. In our experiment the Malaysian strain of DTMUV could be transmitted in the absence of mosquito vectors. These findings may have implications for the control and prevention of this emerging group of flaviviruses.
    Matched MeSH terms: Flavivirus/genetics; Flavivirus/isolation & purification*; Flavivirus Infections/epidemiology; Flavivirus Infections/pathology; Flavivirus Infections/veterinary*; Flavivirus Infections/virology
  12. Serological evidence of DENV, JEV, and ZIKV among the indigenous people (Orang Asli) of Peninsular Malaysia
    Khor CS, Mohd-Rahim NF, Hassan H, Tan KK, Zainal N, Teoh BT, et al.
    J Med Virol, 2020 08;92(8):956-962.
    PMID: 31814135 DOI: 10.1002/jmv.25649
    Dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV) are mosquito-borne flavivirus of medical importance in tropical countries such as Malaysia. However, much remains unknown regarding their prevalence among the underserved indigenous people (Orang Asli) living in communities in the forest fringe areas of Peninsular Malaysia. Information on the prevalence of diseases is necessary to elevate the effectiveness of disease control and preventive measures. This study aimed to determine the seroprevalence of the three major flaviviruses among the Orang Asli and investigate the association between demographic factors and seropositivities. Sampling activities were conducted in the Orang Asli villages to obtain serum samples and demographic data from consenting volunteers. The presence of DENV, JEV, and ZIKV immunoglobulin G (IgG) antibodies in the sera were examined using commercial enzyme-linked immunosorbent assay kits. A focus reduction neutralization assay was performed to measure virus-specific neutralizing antibodies. A total of 872 serum samples were obtained from the Orang Asli volunteers. Serological assay results revealed that DENV IgG, JEV IgG, and ZIKV IgG seropositivities among the Orang Asli were at 4.9%, 48.4%, and 13.2%, respectively. Neutralizing antibodies (FRNT50 ≥ 1:40) against JEV and ZIKV were found in 86.7% and 100.0%, respectively, out of the samples tested. Positive serology to all three viruses corresponded significantly to the age of the volunteers with increasing seropositivity in older volunteers. Findings from the study suggest that Orang Asli are at significant risk of contracting JEV and ZIKV infections despite the lack of active transmission of the viruses in the country.
    Matched MeSH terms: Flavivirus/immunology*
  13. Encephalitis and retarded growth of chicks caused by Sitiawan virus, a new isolate belonging to the genus Flavivirus
    Kono Y, Tsukamoto K, Abd Hamid M, Darus A, Lian TC, Sam LS, et al.
    Am J Trop Med Hyg, 2001 5 19;63(1-2):94-101.
    PMID: 11358004
    A new virus named Sitiawan virus (SV) was isolated from sick broiler chicks in chicken embryos. The virus replicated well with cytopathogenic effect (CPE) in the chicken B-lymphocyte cell line LSCC-BK3. The virus was an enveloped RNA virus of approximately 41 nm in size with hemagglutinating activity (HA) to goose erythrocytes. It was cross-reactive with Japanese encephalitis virus (JEV), a member of flaviviruses by HA inhibition tests but not by cross-virus neutralization tests. The cDNA fragment of NS5 gene was amplified with primers corresponding to NS5 gene of flaviviruses. The nucleotide sequences were 92% homologous to Tembusu virus, a member of the mosquito-borne virus cluster of the genus Flavivirus. In cross-neutralization tests with Tembusu virus, antiserum to SV did not neutralize Tembusu virus, and antiserum to Tembusu virus neutralized more weakly to SV than against homologous virus. These results indicate that SV is a new virus which can be differentiated serologically from Tembusu virus but is otherwise similar with respect to nucleotide sequence. The virus causes encephalitis, growth retardation, and increased blood glucose levels in inoculated chicks.
    Matched MeSH terms: Flavivirus/genetics; Flavivirus/isolation & purification*; Flavivirus/pathogenicity*; Flavivirus/ultrastructure; Flavivirus Infections/epidemiology; Flavivirus Infections/veterinary*; Flavivirus Infections/virology
  14. The distribution of important sero-complexes of flaviviruses in Malaysia
    Kumar K, Arshad SS, Toung OP, Abba Y, Selvarajah GT, Abu J, et al.
    Trop Anim Health Prod, 2019 Mar;51(3):495-506.
    PMID: 30604332 DOI: 10.1007/s11250-018-01786-x
    Flaviviruses (FVs) are arthropod-borne viruses of medical and veterinary importance. Numerous species of FVs have been isolated from various host; mainly humans, animals, ticks, and mosquitoes. Certain FVs are extremely host-specific; at the same time, some FVs can infect an extensive range of species. Based on published literatures, 11 species of FVs have been detected from diverse host species in Malaysia. In humans, dengue virus and Japanese encephalitis virus have been reported since 1901 and 1942. In animals, the Batu Cave virus, Sitiawan virus, Carey Island, Tembusu virus, Duck Tembusu virus, and Japanese encephalitis viruses were isolated from various species. In mosquitoes, Japanese encephalitis virus and Kunjin virus were isolated from Culex spp., while Zika virus and Jugra virus were isolated from Aedes spp. In ticks, the Langat virus was isolated from Ixodes spp. One of the major challenges in the diagnosis of FVs is the presence of sero-complexes as a result of cross-reactivity with one or more FV species. Subsequently, the distribution of specific FVs among humans and animals in a specific population is problematic to assess and often require comprehensive and thorough analyses. Molecular assays such as quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and digital droplet RT-PCR (ddRT-PCR) have been used for the differentiation of flavivirus infections to increase the accuracy of epidemiological data for disease surveillance, monitoring, and control. In situations where sero-complexes are common in FVs, even sensitive assays such as qRT-pCR can produce false positive results. In this write up, an overview of the various FV sero-complexes reported in Malaysia to date and the challenges faced in diagnosis of FV infections are presented.
    Matched MeSH terms: Flavivirus Infections
  15. Rapid dengue diagnosis and interpretation
    Lam SK
    Malays J Pathol, 1993 Jun;15(1):9-12.
    PMID: 8277797
    Matched MeSH terms: Flavivirus/genetics; Flavivirus/isolation & purification
  16. The genetic characteristics and evolution of Tembusu virus
    Lei W, Guo X, Fu S, Feng Y, Tao X, Gao X, et al.
    Vet Microbiol, 2017 Mar;201:32-41.
    PMID: 28284620 DOI: 10.1016/j.vetmic.2017.01.003
    BACKGROUND: Since the turn of the 21st century, there have been several epidemic outbreaks of poultry diseases caused by Tembusu virus (TMUV). Although multiple mosquito and poultry-derived strains of TMUV have been isolated, no data exist about their comparative study, origin, evolution, and dissemination.

    METHODOLOGY: Parallel virology was used to investigate the phenotypes of duck and mosquito-derived isolates of TMUV. Molecular biology and bioinformatics methods were employed to investigate the genetic characteristics and evolution of TMUV.

    PRINCIPAL FINDINGS: The plaque diameter of duck-derived isolates of TMUV was larger than that of mosquito-derived isolates. The cytopathic effect (CPE) in mammalian cells occurred more rapidly induced by duck-derived isolates than by mosquito-derived isolates. Furthermore, duck-derived isolates required less time to reach maximum titer, and exhibited higher viral titer. These findings suggested that poultry-derived TMUV isolates were more invasive and had greater expansion capability than the mosquito-derived isolates in mammalian cells. Variations in amino acid loci in TMUV E gene sequence revealed two mutated amino acid loci in strains isolated from Malaysia, Thailand, and Chinese mainland compared with the prototypical strain of the virus (MM1775). Furthermore, TMUV isolates from the Chinese mainland had six common variations in the E gene loci that differed from the Southeast Asian strains. Phylogenetic analysis indicated that TMUV did not exhibit a species barrier in avian species and consisted of two lineages: the Southeast Asian and the Chinese mainland lineages. Molecular traceability studies revealed that the recent common evolutionary ancestor of TMUV might have appeared before 1934 and that Malaysia, Thailand and Shandong Province of China represent the three main sources related to TMUV spread.

    CONCLUSIONS: The current broad distribution of TMUV strains in Southeast Asia and Chinese mainland exhibited longer-range diffusion and larger-scale propagation. Therefore, in addition to China, other Asian and European countries linked to Asia have used improved measures to detect and monitor TMUV related diseases to prevent epidemics in poultry.

    Matched MeSH terms: Flavivirus/genetics*; Flavivirus/isolation & purification; Flavivirus/physiology; Flavivirus Infections/transmission; Flavivirus Infections/veterinary*; Flavivirus Infections/virology
  17. Epitope Identification and Application for Diagnosis of Duck Tembusu Virus Infections in Ducks
    Li C, Liu J, Shaozhou W, Bai X, Zhang Q, Hua R, et al.
    Viruses, 2016 Nov 10;8(11).
    PMID: 27834908
    Duck Tembusu virus (DTMUV) causes substantial egg drop disease. DTMUV was first identified in China and rapidly spread to Malaysia and Thailand. The antigenicity of the DTMUV E protein has not yet been characterized. Here, we investigated antigenic sites on the E protein using the non-neutralizing monoclonal antibodies (mAbs) 1F3 and 1A5. Two minimal epitopes were mapped to (221)LD/NLPW(225) and (87)YAEYI(91) by using phage display and mutagenesis. DTMUV-positive duck sera reacted with the epitopes, thus indicating the importance of the minimal amino acids of the epitopes for antibody-epitope binding. The performance of the dot blotting assay with the corresponding positive sera indicated that YAEYI was DTMUV type-specific, whereas (221)LD/NLPW(225) was a cross-reactive epitope for West Nile virus (WNV), dengue virus (DENV), and Japanese encephalitis virus (JEV) and corresponded to conserved and variable amino acid sequences among these strains. The structure model of the E protein revealed that YAEYI and LD/NLPW were located on domain (D) II, which confirmed that DII might contain a type-specific non-neutralizing epitope. The YAEYI epitope-based antigen demonstrated its diagnostic potential by reacting with high specificity to serum samples obtained from DTMUV-infected ducks. Based on these observations, a YAEYI-based serological test could be used for DTMUV surveillance and could differentiate DTMUV infections from JEV or WNV infections. These findings provide new insights into the organization of epitopes on flavivirus E proteins that might be valuable for the development of epitope-based serological diagnostic tests for DTMUV.
    Matched MeSH terms: Flavivirus/immunology*; Flavivirus Infections/diagnosis; Flavivirus Infections/veterinary*
  18. An infectious full-length cDNA clone of duck Tembusu virus, a newly emerging flavivirus causing duck egg drop syndrome in China
    Li S, Zhang L, Wang Y, Wang S, Sun H, Su W, et al.
    Virus Res, 2013 Jan;171(1):238-41.
    PMID: 23116594 DOI: 10.1016/j.virusres.2012.10.019
    Duck Tembusu virus (TMUV) is a recently identified pathogenic flavivirus that causes severe egg drop and encephalitis in Chinese ducks and geese. It has been found to be most closely related to the mosquito-origin Tembusu virus and chicken Sitiawan virus reported in Malaysia. However, the ecological characteristics and the pathogenesis of duck TMUV are largely unknown. We report the construction of full-length cDNA clone of duck TMUV strain JXSP. The virus genome was reverse transcribed, amplified as seven overlapping fragments and successively ligated into the low copy number vector pWSK29 under the control of a T7 promoter. Transfection of BHK-21 cells with the transcribed RNA from the full-length cDNA clone resulted in production of highly infectious progeny virus. In vitro growth characteristics in BHK-21 cells and virulence in ducklings and BALB/c mice were similar for the rescued and parental viruses. This stable infectious cDNA clone will be a valuable tool for studying the genetic determinants of duck TMUV.
    Matched MeSH terms: Flavivirus/genetics*; Flavivirus/growth & development; Flavivirus Infections/veterinary*
  19. Fulltext A novel goose-origin Tembusu virus exhibits pathogenicity in day-old chicks with evidence of direct contact transmission
    Liu M, Chen YY, Twu NC, Wu MC, Fang ZS, Dubruel A, et al.
    Poult Sci, 2024 Feb;103(2):103332.
    PMID: 38128459 DOI: 10.1016/j.psj.2023.103332
    In late 2020, an outbreak of Tembusu virus (TMUV)-associated disease occurred in a 45-day-old white Roman geese flock in Taiwan. Here, we present the identification and isolation of a novel goose-origin TMUV strain designated as NTU/C225/2020. The virus was successfully isolated using minimal-pathogen-free duck embryos. Phylogenetic analysis of the polyprotein gene showed that NTU/C225/2020 clustered together with the earliest isolates from Malaysia and was most closely related to the first Taiwanese TMUV strain, TP1906. Genomic analysis revealed significant amino acid variations among TMUV isolates in NS1 and NS2A protein regions. In the present study, we characterized the NTU/C225/2020 culture in duck embryos, chicken embryos, primary duck embryonated fibroblasts, and DF-1 cells. All host systems were susceptible to NTU/C225/2020 infection, with observable lesions. In addition, animal experiments showed that the intramuscular inoculation of NTU/C225/2020 resulted in growth retardation and hyperthermia in day-old chicks. Gross lesions in the infected chicks included hepatomegaly, hyperemic thymus, and splenomegaly. Viral loads and histopathological damage were displayed in various tissues of both inoculated and naïve co-housed chicks, confirming the direct chick-to-chick contact transmission of TMUV. This is the first in vivo study of a local TMUV strain in Taiwan. Our findings provide essential information for TMUV propagation and suggest a potential risk of disease outbreak in chicken populations.
    Matched MeSH terms: Flavivirus*
  20. The zoonotic flaviviruses of southern, south-eastern and eastern Asia, and Australasia: the potential for emergent viruses
    Mackenzie JS, Williams DT
    Zoonoses Public Health, 2009 Aug;56(6-7):338-56.
    PMID: 19486319 DOI: 10.1111/j.1863-2378.2008.01208.x
    The genus Flaviviridae comprises about 70 members, of which about 30 are found in southern, south-eastern and eastern Asia and Australasia. These include major pathogens such as Japanese encephalitis (JE), West Nile (WN), Murray Valley encephalitis (MVE), tick-borne encephalitis, Kyasanur Forest disease virus, and the dengue viruses. Other members are known to be associated with mild febrile disease in humans, or with no known disease. In addition, novel flaviviruses continue to be discovered, as demonstrated recently by New Mapoon virus in Australia, Sitiawan virus in Malaysia, and ThCAr virus in Thailand. About 19 of these viruses are mosquito-borne, six are tick-borne, and four have no known vector and represent isolates from rodents or bats. Evidence from phylogenetic studies suggest that JE, MVE and Alfuy viruses probably emerged in the Malaya-Indonesian region from an African progenitor virus, possibly a virus related to Usutu virus. WN virus, however, is believed to have emerged in Africa, and then dispersed through avian migration. Evidence suggests that there are at least seven genetic lineages of WN virus, of which lineage 1b spread to Australasia as Kunjin virus, lineages 1a and 5 spread to India, and lineage 6 spread to Malaysia. Indeed, flaviviruses have a propensity to spread and emerge in new geographic areas, and they represent a potential source for new disease emergence. Many of the factors associated with disease emergence are present in the region, such as changes in land use and deforestation, increasing population movement, urbanization, and increasing trade. Furthermore, because of their ecology and dependence on climate, there is a strong likelihood that global warming may significantly increase the potential for disease emergence and/or spread.
    Matched MeSH terms: Flavivirus/classification*; Flavivirus/pathogenicity; Flavivirus Infections/epidemiology; Flavivirus Infections/transmission*; Flavivirus Infections/veterinary*
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