Encephalitis and retarded growth of chicks caused by Sitiawan virus, a new isolate belonging to the genus Flavivirus.

Abstract

Abstract.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.

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

“…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. 10 The data presented here also support the role of mosquitoes in the spread of duck TMUV in China in addition to the possible oral route of spread as described for sparrows in China. 21 Although TMUV has not emerged as a recognized disease in humans or animals in Thailand, continuous surveillance will be necessary to prevent economic losses caused by the emergence of a more virulent TMUV strain.…”

“…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.…”

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).…”

Isolation and genome characterization of a novel duck Tembusu virus with a 74 nucleotide insertion in the 3′ non-translated region

“…TMUV was first described in 1957 in Kuala Lumpur, Malaysia. A chickorigin TMUV strain, originally designated as Sitiawan virus, was reported later causing encephalitis and retarded growth in broiler chicks (Kono et al, 2000). Clinical investigations demonstrated the DTMUV could also affect geese.…”