An infectious disease of ducks caused by a newly emerged Tembusu virus strain in mainland China

Abstract

During investigations into an outbreak of egg production decline, retarded growth, and even death among ducks in Southeast China, a novel Tembusu virus strain named Tembusu virus Fengxian 2010 (FX2010) was isolated. This virus replicated in embryonated chicken eggs and caused embryo death. In cross-neutralization tests, antiserum to the partial E protein of Tembusu virus Mm1775 strain neutralized FX2010, whereas antiserum to Japanese encephalitis virus did not. FX2010 is an enveloped RNA virus of approximately 45-50 nm in diameter. Sequence analysis of its E and NS5 genes showed that both genes share up to 99.6% nucleotide sequence identity with Baiyangdian virus, and up to 88% nucleotide sequence identity with their counterparts in Tembusu virus. FX2010 was transmitted without mosquito, and caused systemic infection and lesions in experimentally infected ducks. These results indicate that FX2010 and BYD virus are newly emerged Tembusu virus strains that cause an infectious disease in ducks.

Field Detection of Tembusu Virus in Western Thailand by RT-PCR and Vector Competence Determination of Select Culex Mosquitoes for Transmission of the Virus

“…However, disease (ovarian hemorrhage and hyperemia with neurological sequelae) in animals has been noted in China and Malaysia. [9][10][11] Here, we report the isolation of TMUV in Thailand and provide the first report of vector competence testing to show that field-caught mosquitoes can be efficient vectors for spreading the virus in Thailand and elsewhere.…”

“…24 Despite TMUV not being recognized as causing disease in humans (or poultry in Thailand, although TMUV was isolated from ducks from Thailand), TMUV has had a significant impact on the duck industry in China (first recognized in April of 2010), with reports of an approximately 90% drop in egg production and 5-30% mortality in the birds. 9,11,25 Phylogenetic analysis of the TMUV strains isolated from the Thai ducks and mosquitoes indicates that they are closely related to the duck TMUV from China and may be causing an unrecognized morbidity and mortality in Thailand in wild birds and poultry, because infection of leghorn chicks with TMUV strain Thai-MLO305 caused growth retardation and death in young chickens. This effect was also noted previously for Sitiawan virus (a strain of TMUV, although it was originally named differently) and its consequence on broiler chicks.…”

In vitro and in vivo characterization of chimeric duck Tembusu virus based on Japanese encephalitis live vaccine strain SA14-14-2

“…DTMUV was initially also referred to as duck eggdrop syndrome virus (DEDSV), and DTMUV-infected ducks develop a severe disease characterized by a drop in egg production, acute anorexia, retarded growth and neurological dysfunction (Yan et al, 2011b). DTMUV infection has caused huge economic losses in duck-farming with over 10 million shelducks infected and approximately one million dead (Yan et al, 2011a).…”

Development of Conventional and Real-Time Reverse Transcription Polymerase Chain Reaction Assays to Detect Tembusu Virus in Culex tarsalis Mosquitoes

“…Although TMUV was first isolated in 1955 in Malaysia 3 and more recently, in regions of southeast Asia, including Thailand and China, [5][6][7][8][9][10][11][12][13] relatively little is known about this virus. We developed conventional PCR primers specific for the TMUV envelope gene and tested the primer pair to determine the most ideal conditions for detection of TMUV RNA.…”

“…4 To date, little is known about TMUV; however, several recent reports indicate that TMUV and TMUV-like viruses have also been isolated in other regions of southeast Asia, including Thailand and China. [5][6][7][8][9][10][11][12][13] Like other flaviviruses, TMUV is a linear, positive-sense, single-stranded RNA virus with a genome size of approximately 11 kb. Its RNA encodes 10 proteins, including three structural proteinsthe capsid (C) protein, the membrane (M) protein, and the envelope (E) glycoprotein-and seven non-structural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5).…”