Construction of the recombinant duck enteritis virus delivering capsid protein VP0 of the duck hepatitis A virus.

Duck hepatitis A virus type 1 (DHAV-1) disease causes significant economic losses to the duck industry. Duck enteritis virus (DEV) is frequently used as a viral vector for aquatic poultry vaccination, but no recombinan DEV expressing DHAV-1 VP0 has been developed. In this study, we established a system for rescuing the DEV C-KCE vaccine strain by transfecting cells with six fosmid DNAs. We generated a recombinant virus (rDEV-ul41VP0) by inserting the VP0 gene of DHAV-1 into the ul41 region in the DEV C-KCE genome. DHAV-1 VP0 was stably expressed in the rDEV-ul41VP0 infected cells, but did not affect the replication properties of DEV C-KCE in cells. Duck experiments showed that rDEV-ul41VP0 could provided full protection against the lethal DEV Chinese standard challenge (DEV CSC) and conferred 70% protection against DHAV-1 161/79 at 3 days postvaccination. These results indicate that rDEV-ul41VP0 rapidly induces protection against DEV CSC and DHAV-1 in ducks, and can be served as a bivalent vaccine against DEV and DHAV-1.

Comparative genetic analysis and pathological characteristics of goose parvovirus isolated in Heilongjiang, China.

BACKGROUND: Goose parvovirus (GPV) causes acute enteritis, hepatitis, myocarditis and high morbidity and mortality in geese and ducks. GPV H strain was isolated from a Heilongjiang goose farm where the geese were showing signs of hemorrhage in the brain, liver, and intestinal tract. In this study, we explored the genetic diversity among waterfowl parvovirus isolates and the pathological characteristics of GPV H in Shaoxing ducklings. METHODS: The complete capsid protein (VP) and non-structural (NS) sequences of the isolated H strain were sequenced, and phylogenetic trees of VP and NS were constructed in MEGA version 5.05 using the neighbor-joining method. Three-day-old Shaoxing ducklings were inoculated with GPV and were euthanized at 1, 2, 4, 6, and 8 days post-inoculation (PI), and their organs were removed and collected. The organs of 6-day PI ducklings were fixed in formalin, embedded in paraffin, sectioned for histology, stained with HE and analyzed for pathological lesions. The distribution of the GPV H strain in the tissues of the inoculated ducklings was detected using the polymerase chain reaction (PCR) method. RESULTS: Genetic analysis of the NS and VP genes indicated that the H strain was closely related to strains circulating in China during 1999-2014, and the nucleic acid identity of those strains was 98%-99%. Classical symptoms were observed in the inoculated ducklings. GPV remained in many tissues and replicated in a majority of the tissues, leading to histopathological lesions in four tissues. CONCLUSIONS: We first reported the distribution and histopathological lesions of a Chinese strain of GPV in infected shaoxing ducklings. This H strain was moderate pathogenic for Shaoxing ducklings.