Evaluation of a novel inactivated vaccine against duck circovirus in muscovy ducks.

Duck circovirus (DuCV), an immunosuppressive pathogen, causes serious damage to waterfowls worldwide. A highly efficient vaccine would play a crucial role in preventing DuCV infections in the waterfowl breeding industry. However, to date, there is a dearth of commercial vaccines owing to the lack of a cell culture system for propagating the requisite virus amounts in vitro. In this study, we isolated DuCVs from Muscovy ducks, helped them proliferate using peripheral blood mononuclear cells (PBMCs), and developed an inactivated vaccine. Muscovy ducks vaccinated with the inactivated vaccine had higher neutralizing antibody titers than the control ducks and higher protection in the challenge experiment (as assessed by weight measurement). Moreover, the inactivated vaccine did not cause feather abnormalities, growth repression, and dwarf syndrome; likewise, lesions and lymphocyte apoptosis in the bursa of Fabricius, spleen, and thymus were not observed. Significantly lower virus shedding from the inactivated vaccine was detected up to 42 days post-inoculation. Together, these results suggest that the inactivated DuCV vaccine can induce a high immune response, is relatively safer for Muscovy ducks, and thus it is a protective vaccine candidates against DuCV infection.

Genomic analysis of Sheldrake origin goose hemorrhagic polyomavirus, China

Goose hemorrhagic polyomavirus (GHPV) is not a naturally occurring infection in geese in China; however, GHPV infection has been identified in Pekin ducks, a domestic duck species. Herein, we investigated the prevalence of GHPV in five domestic duck species (Liancheng white ducks, Putian black ducks, Shan Sheldrake, Shaoxing duck, and Jinyun Sheldrake) in China. We determined that the Jinyun Sheldrake duck species could be infected by GHPV with no clinical signs, whereas no infection was identified in the other four duck species. We sequenced the complete genome of the Jinyun Sheldrake origin GHPV. Genomic data comparison suggested that GHPVs share a conserved genomic structure, regardless of the host (duck or geese) or region (Asia or Europe). Jinyun Sheldrake origin GHPV genomic characterization and epidemiological studies will increase our understanding of potential heterologous reservoirs of GHPV.

Epidemiological Investigation and Genome Analysis of Duck Circovirus in Southern China / 中国病毒学·英文版

Duck circovirus(DuCV),a potential immunosuppressive virus,was investigated in Southern China from March 2006 to December 2009 by using a polymerase chain reaction(PCR)based method. In this study,a total of 138 sick or dead duck samples from 18 different farms were examined with an average DuCV infection rate of～35%. It was found that ducks between the ages of 40～60 days were more susceptible to DuCV. There was no evidence showing that the DuCV virus was capable of vertical transmission. Farms with positive PCR results exhibited no regularly apparent clinical abnormalities such as feathering disorders,growth retardation or lower-than-average weight. The complete genomes of 9. strains from Fujian Province and 1 from Zhejiang Province were sequenced and analyzed. The 10 DuCV genomes,compared with others genomes downloaded from GenBank,ranged in size from 1988 to 1996 base pairs,with sequence identities ranging from 83.2% to 99.8%. Phylogenetic analysis based on genome sequences demonstrated that DuCVs can be divided into two distinct genetic genotypes,Group I(the Euro-USA lineage)and Group II(the Taiwan lineage),with approximately 10.0% genetic difference between the two types. Molecular epidemiological data suggest there is no obvious difference among DuCV strains isolated from different geographic locations or different species,including Duck,Muscovy duck,Mule duck,Cheery duck,Mulard duck and Pekin duck.