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Tembusu virus (TMUV) has been a causative agent of an acute egg-drop syndrome found in Chinese duck populations since at least 2010. In this paper, we report the characterization of a TMUV-like flavivirus (named CJD05) isolated from naturally infected egg-laying fowl. The virus was identified and then isolated from hens suffering from severe egg drop and fever in Fujian Province, China. The virus replicated well in MDEF and CEF cells, and its cytopathogenic effect (CPE) was apparent. Hemagglutinating activity (HA) was negative for this virus using erythrocytes from both chickens and pigeons. Viral particles were enveloped and approximately 45 nm in diameter, as observed by electron microscopy. Phylogenetic analysis of the full-length nucleotide sequence of CJD05 indicated that this virus is closely related to the duck-origin TMUV, belonging to Ntaya group of flavivirus. Most importantly, pathogenicity studies showed that CJD05 is highly virulent in 1-day-old chicks, 1-day-old Muscovy ducks, egg-laying chickens and shelducks. Our research highlights the increase in epidemic disease caused by avian TMUV, and subsequent outbreaks are becoming more complicated to treat. The pathogenic mechanisms of the virus are still not fully understood, further research is needed. [ABSTRACT FROM AUTHOR]

The complete sequence of a reovirus, strain NP03 associated with necrotic focus formation in the liver and spleen of Muscovy ducklings in Fujian Province, China in 2009, was determined and compared with sequences of other waterfowl and chicken-origin avian reoviruses (ARVs). Sequencing of the complete genomes of strain NP03 showed that they consisted of 23,418 bp and were divided into 10 segments, ranging from 1191 bp (S4) to 3959 bp (L1) in length, and all segments contained conserved sequences in the 5′ non-coding region (GCUUUU) and 3' non-coding region (UCAUC). Pairwise sequence comparisons demonstrated that NP03 strain showed the highest similarity with novel waterfowl origin reoviruses (WRVs). The genome analysis revealed that the S1 segment of novel WRV is a tricistronic gene, encoding the overlapping open reading frames (ORFs) for p10, p18, and σC, similar to the ARV S1 gene, but distinct from classical WRV S4 genome segment, which contained two overlapping ORFs encoding p10 and σC. Phylogenetic analyses of the nucleotide sequences of all 10 segments revealed that NP03 strain was clustered together with other novel WRVs and were distinct from classical WRVs and chicken-origin ARVs. The analyses also showed possible intra-segmental reassortment events in the segments encoding λA, λB, μB, μNS, σA, and σNS between novel and classical WRVs. Potential recombination events detection in segment L1 suggests that NP03 strain may be recombinants of novel WRVs. Based on our genetic analyses, multiple reassortment events, intra-segmental recombination, and accumulation of point mutations have possibly contributed to the emergence of this novel genotype of WRV, identified in China. • There were two genotypes of waterfowl reovirus (WRV), which mainly causes the outbreaks in China. • The novel WRV strain NP03 likely derived from multiple reassortment events. • Possible intra-segmental recombination event was identified. [ABSTRACT FROM AUTHOR]