Development of a live attenuated duck hepatitis A virus type 3 vaccine (strain SD70). Issue 30 (19th June 2020)

• Record Type: Journal Article
• Authors: Wu, Fengyao; Lu, Fengying; Fan, Xin; Pan, Qunxing; Zhao, Sha; Sun, Huawei; Zhang, Jingfeng; Liu, Chuanmin; Chao, Jin; Zhang, Xiaofei
• Is Part Of: Vaccine. Volume 38:Issue 30(2020)
• Page Start: 4695
• Page End: 4703
• Publication Date: 2020-06-19
• Subjects: Duck hepatitis A virus type 3 (DHAV-3) -- Attenuated live vaccine -- Safety -- Stability -- Protective efficiency -- Genomic sequence analysis; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2020.05.030
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: We found a feasible way to attenuate DHAV-3. SD70 strain was developed as a live attenuated DHAV-3 vaccine candidate. This vaccine candidate exhibited safety, good stability and excellent protection. One dose of SD70 vaccine is sufficient to protect ducklings from DHAV-3 infection. Abstract: Duck hepatitis A virus type 3 (DHAV-3) is an important pathogen that causes substantial losses in the Chinese duck industry. DHAV-3 is highly fatal to ducklings and there is no licensed vaccine in China available to reduce DHAV-3 infection. Our goal was to develop a live attenuated vaccine candidate against DHAV-3. A field isolated strain, SD, was attenuated by serially passaging in specific-pathogen-free (SPF) chicken embryos, and it lost its pathogenicity after 40 passages. The 70th passaged strain (SD70), which achieved good growth capacity in chicken embryos with a viral titer of 10 7.5 ELD50 /mL, was chosen to be the live attenuated vaccine candidate. The SD70 strain did not cause clinical signs of disease or mortality in 1-day-old ducklings and showed no virulence reversion after seven rounds of in vivo back passages. The minimum effective dose of SD70 was determined to be 10 2.5 ELD50 via the vaccination route of subcutaneous inoculation. A single dose of the SD70 provided good protection to susceptible ducklings against the lethal DHAV-3 strain. Compared with the genomic sequence of the parent SD strain, the SD70 had 12 amino acid substitutions, some of which may play a role in virulence attenuation. This study demonstrated that the attenuated SD70 strain is a promising vaccine candidate for the prevention of DHAV-3 infection in China. It exhibited safety, good stability and excellent protection.