Analysis of the Complete Genome of Tembusu Virus, a Flavivirus Isolated from Ducks in China

Abstract

During investigations into the outbreak of duck viral infection in 2010 in China, with a severe drop in egg production, a flavivirus was isolated from the affected ducks. It was characterized as a Tembusu virus (TMUV). In this study, we obtained a complete genome sequence of Tembusu virus using RT-PCR and RACE techniques. TMUV genome is a singled-stranded RNA, with 10,990 nucleotides in length, and contains a single open reading frame (3410 amino acids) encoding 11 viral proteins with 5'and 3'non-translated regions (NTRs) of 142 and 618 nt, respectively. We characterized the open reading frame (ORF) with respect to gene sizes, cleavage sites and potential glycosylation sites. The different genomic regions of the virus were also compared with those of six other flaviviruses including Japanese encephalitis virus, West Nile virus (WNV), dengue-2 virus, yellow fever virus, tick-borne encephalitis virus (TBEV) and Bagaza virus. TMUV demonstrated the highest similarity to Bagaza virus. The result of entire ORF scanning shows that TMUV was close to Bagaza viruses in genetic relatedness. These data demonstrate that TMUV is a unique virus among the mosquito-borne flaviviruses and also provide a useful reference for a critically important study to determine why TMUV is a serious pathogen for ducks.

Comparison of four molecular assays for the detection of Tembusu virus

“…A chick-origin TMUV strain, originally named Sitiawan virus, can cause encephalitis and impede growth in broiler chicks (Kono et al, 2000). Outbreaks of TMUV infection with severe egg-drop in many egg-laying and breeder duck farms were observed in China (Cao et al, 2011;Su et al, 2011;Tang et al, 2011a;Yan et al, 2011b;Liu et al, 2012). The affected ducks showed significant egg-drop.…”

Duck egg drop syndrome virus: an emerging Tembusu-related flavivirus in China

“…However, Liu et al [30] report a different prediction, where the PrM is longer, and NS1 is shorter (the difference in each is 10 aa). Another report from Diao's group includes an absolutely distinct prediction, in which most of the cleavage sites are not identical to other predictions [19].…”

“…Compared to other Ntaya group viruses, DEDSV has a CS pattern of CS1-CS2-RCS2-CS3-RCS3 [15,17,19,25], which is also shared by JEV complex viruses. However, BAGV, ILHV, and ROCV are different from DEDSV.…”

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

“…The affected ducks (including Pekin duck, Cherry Valley Pekin duck, Shaoxing duck, Jinyun duck, Longyan duck, Jinding duck and Khaki-Campbell duck) showed severe drops in egg production, declines in feed uptake, paralysis, severe oophoritis and regression and mortality (Su et al, 2011;Tang et al, 2012;Yun et al, 2012a). Hyperaemia, haemorrhage, degeneration, distortion and lymphocyte infiltration in ovaries and interstitial inflammation in the portal areas of livers were the main pathological changes observed consistently in almost all diseased ducks.…”

“…A report about TMUV-SDHS isolated from house sparrows showed a close relationship with the YY5 strain, and this latter strain was highly pathogenic to ducks. This finding may play an important role in transmitting the virus among different species (Tang et al, 2012). In view of the epidemic characteristics of the DTMUV, as well as the hazard and losses that it caused in the duck industry, more attention to the virus is needed.…”