In China in 2010, a disease outbreak in egg-laying ducks was associated with a flavivirus. The virus was isolated and partially sequenced. The isolate exhibited 87%–91% identity with strains of Tembusu virus, a mosquito-borne flavivirus of the Ntaya virus group. These findings demonstrate emergence of Tembusu virus in ducks.

The effects of three different adjuvants, mineral oil, Montanide™ ISA 70M VG, and Montanide™ ISA 206 VG, were evaluated on reverse genetics H5N3 avian influenza virus cell cultured vaccine. The immune results of SPF chickens after challenging with highly pathogenic avian influenza (HPAI) virus demonstrated that mineral oil adjuvant group and 70M adjuvant group provided 100% protection efficiency, but 206 adjuvant group provided only 40%. Statistical analysis indicated that the protection effects of mineral oil adjuvant group and the 70M adjuvant showed no significant difference to each other, but with significant difference to 206 adjuvant group. All three groups could induce high titres of antibody after immunizing SPF ducks, but there was no significant difference among them. The immunization effect of 70M adjuvant group on SPF chickens were the best and showed significant difference compared with optimized 70Mi Montanide™ eight series adjuvants groups. These results suggest that 70M adjuvant could be a novel adjuvant for preparing avian influenza vaccine.

Avian tembusu-related virus, which was first identified in China, is an emerging virus causing serious economic loss to the Chinese poultry industry. We report here the complete genome sequences of avian tembusu-related virus strain WR, isolated from a White Kaiya duck with disease characterized by an abrupt decrease in egg laying with ovarian hemorrhage, which will help in further understanding the molecular and evolutionary characteristics and pathogenesis of avian tembusu-related virus, the new flavivirus affecting ducks in Southern China.

This report describes a one-step real-time polymerase chain reaction assay based on SYBR Green I for detection of a broad range of duck circovirus (DuCV). Align with all DuCV complete genome sequences and other Genus Circovirus download from the GenBank (such as goose circovirus, pigeon circovirus), the primers targets to the replicate gene of DuCV were designed. The detection assay was linear in the range of 1.31 × 10²-1.31 × 10⁷ copies/μL. The reaction efficiency of the assay using the slope (the slope was -3.349) and the Y-intercept was 37.01 from the linear equation was estimated to be 0.99 and the correlation coefficient (R²) was 0.993. A series of experiments were carried out to assess the reproducibility, sensitivity, and specificity of the assay, following by the low intra-assay and inter-assay CVs for CT values obtained with the standard plasmids. The intra-assay CVs were equal or less than 1.89% and the inter-assay CVs were equal or less than 1.26%. There was no cross-reaction occurred with nucleic acids extracted from RA (Riemerella anatipestifer), E. coli (Escherichia coli), Duck Cholera (Pasteurella multocida), Avian influenza virus, avian paramyxovirus, Muscovy duck parvovirus, Duck reovirus, Duck hepatitis A virus as control templates. The nucleic acids extracted from samples of healthy ducks were used as negative controls. The assay was specific and reproducible. The established real time PCR was used to detect 45 DuCV-negative samples, which were tested using conventional PCR under the developed optimal conditions, each 15 for embryonated eggs, non-embryonated budgerigar eggs, newly hatched duck, the mixture of the lung, liver, spleen which were analysis for the presence of DuCV DNA, to conform that whether the DuCV can be transmitted vertically. Meanwhile, no positive result was shown by the real-time PCR method. The SYBR Green I-based quantitative PCR can therefore be practically used as an alternative diagnostic tool and a screening method for ducks infected with duck circovirus.

A virulent Riemerella anatipestifer bacteriophage, RAP44, belonging to the Siphoviridae family of tailed phages, was previously isolated from feces of healthy Muscovy ducks in China. A complete genomic sequence analysis indicates that the phage's genome consists of a linear, double-stranded DNA molecule of 49,329 nucleotides. Eighty open reading frames (ORF) were identified. Putative functions could be assigned to 24 of the ORFs. The location of these genes was consistent with organization of the genome in a modular format which includes modules for host cell lysis, tail morphogenesis, head morphogenesis, and DNA replication and modification modules. Until now, no R. anatipestifer phage genome sequence has been reported in the literature. Therefore, this study represents the first complete genomic and molecular description of the R. anatipestifer phage.