Abstract
Orally delivered DNA vaccines against duck enteritis virus (DEV) were developed using live attenuated Salmonella typhimurium (SL7207) as a carrier and Escherichia coli heat labile enterotoxin B subunit (LTB) as a mucosal adjuvant. DNA vaccine plasmids pVAX-UL24 and pVAX-LTB-UL24 were constructed and transformed into attenuated Salmonella typhimurium SL7207 resulting SL7207 (pVAX-UL24) and SL7207 (pVAX-LTB-UL24) respectively. After ducklings were orally inoculated with SL7207 (pVAX-UL24) or SL7207 (pVAX-LTB-UL24), the anti-DEV mucosal and systemic immune responses were recorded. To identify the optimum dose that confers maximum protection, we used different doses of the candidate vaccine SL7207 (pVAX-LTB-UL24) during oral immunization. The strongest mucosal and systemic immune responses developed in the SL7207 (pVAX-LTB-UL24) (1011 CFU) immunized group. Accordingly, oral immunization of ducklings with SL7207 (pVAX-LTB-UL24) showed superior efficacy of protection (60-80%) against a lethal DEV challenge (1000 LD50), compared with the limited survival rate (40%) of ducklings immunized with SL7207 (pVAX-UL24). Our study suggests that the SL7207 (pVAX-LTB-UL24) can be a candidate DEV vaccine.
Highlights
Duck viral enteritis (DVE, called duck plague), caused by Anatid herpesvirus 1 (Duck enteritis virus, duck enteritis virus (DEV)), is an acute, contagious viral disease of ducks, geese and swans, accounting for a high mortality rate in ducks and decreased egg production, leading to heavy economic losses [1,2,3,4]
Construction and transient expression of pVAX-UL24 and pVAX-labile enterotoxin B subunit (LTB)-UL24 in COS-7 cells Indirect immunofluorescence experiments demonstrated that specific fluorescent granules dispersed in the nucleus and cytoplasm in the cells transfected with pVAXUL24 or pVAX-LTB-UL24 (Figure 2D-I), whereas no fluorescence was detected in cells infected with plasmid pVAX1 (Figure 2A-C), indicating that UL24 and LTBUL24 were expressed in COS-7 cells
Transcripts of UL24 and LTB-UL24 genes in vivo To test the expression of DEV DNA vaccines in vivo, total cellular RNA of ilea was isolated at day 3 after immunization, and was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) for the transcripts of UL24 or LTB-UL24 gene
Summary
Duck viral enteritis (DVE, called duck plague), caused by Anatid herpesvirus 1 (Duck enteritis virus, DEV), is an acute, contagious viral disease of ducks, geese and swans, accounting for a high mortality rate in ducks and decreased egg production, leading to heavy economic losses [1,2,3,4] The symptoms of this disease include vascular damage, eruptions at specific locations on the mucosal surface of the gastrointestinal tract, lesions. Some enteropathogenic bacteria [10] have been used as effective carriers for DNA vaccine including attenuated strains of Listeria monocytogenes [11], Salmonella spp [12] and Shigella spp [13] These bacteria are attractive vectors to deliver DNA vaccines to immunological inductive sites at mucosal surfaces and antigen-presenting cells (APC), which can improve mucosal and systemic responses against pathogens [14,15]. These strategies of DNA vaccine combined with adjuvant might provide new opportunities in the development of DEV vaccine
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call