A divalent DNA vaccine based on Sia10 and OmpU induces cross protection against Streptococcus iniae and Vibrio anguillarum in Japanese flounder

• Published in: Fish & Shellfish Immunology
• Main Authors: Sun, Yun, Zhang, Min, Liu, Chun-sheng, Qiu, Reng, Sun, Li, Sun, L (reprint author), Chinese Acad Sci, Inst Oceanol, Key Lab Expt Marine Biol, 7 Nanhai Rd, Qingdao 266071, Peoples R China.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Streptococcus Iniae; Vibrio Anguillarum; Paralichthys Olivaceus; Dna Vaccine; Cross Protection; Fisheries; Immunology; Marine & Freshwater Biology; Veterinary Sciences; Scophthalmus maximus; Turbot
• Online Access: http://ir.qdio.ac.cn/handle/337002/12256; https://doi.org/10.1016/j.fsi.2012.03.024

Streptococcosis and vibriosis caused by Streptococcus iniae and Vibrio anguillarum respectively have affected fish culture industries around the world. Previous studies have indicated that the S. iniae antigen Sia10 and the V. anguillarum outer membrane protein OmpU, when used as DNA vaccines, induce protection in turbot (Scophthalmus maximus) and Asian seabass (Lates calcarifer) respectively. In this study, with an effort to develop effective vaccines against S. iniae and V. anguillarum, we constructed three DNA vaccines based on Sia10 and OmpU and examined their immune effects in a model of Japanese flounder (Paralichthys olivaceus), which in China is known to suffer from both streptococcosis and vibriosis. Of the three DNA vaccines constructed in this study, pIDSia10 and pIDOmpU express Sia10 and OmpU respectively, while pSiVal expresses Sia10 and OmpU as two individual proteins translated from a single bicistronic mRNA transcript. At 7 and 28 days post-vaccination, vaccine plasmids and expression of the vaccine-encoding genes were detected in the muscle, spleen, kidney, and liver of the vaccinated fish. lmmunocolloidal gold electron microscopy detected production of Sia10 and OmpU proteins in pIDSia10- and pIDOmpU-vaccinated fish respectively, while both Sia10 and OmpU proteins were detected in pSiVa1-vaccinated fish. At one and two months post-vaccination, fish vaccinated with pIDSia10 and pSiVa1 exhibited comparable relative percent of survival (RPS) rates (80%-87%) following lethal S. iniae challenge. Similar protection rates were produced by fish vaccinated with pIDOmpU and pSiVal following lethal V. anguillarum challenge. Immunological analysis showed that (i) all vaccines induced specific serum antibody production which enhanced complement-mediated bactericidal activity, and (ii) pSiVal modulated the expression of a wide spectrum of immune relevant genes in a time-dependent manner. Together these results indicate that pSiVal is an effective bivalent vaccine that induces strong cross protection in ...