Polymeric immunoglobulin receptor and mucosal IgM responses elicited by immersion and injection vaccination with inactivated Vibrio anguillarum in flounder (Paralichthys olivaceus)

• Published in: Aquaculture 2019-04, Vol.505, p.1-11
• Main Authors: Sheng, Xiuzhen, Chai, Baihui, Wang, Zhanfei, Tang, Xiaoqian, Xing, Jing, Zhan, Wenbin
• Format: Article
• Language: English
• Subjects: Flounder (Paralichthys olivaceus); Mucosal immune response; Polymeric immunoglobulin receptor (pIgR); Secretory IgM; Vaccination; Vibrio anguillarum
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2019.02.045

Polymeric immunoglobulins (Igs) and polymeric immunoglobulin receptor (pIgR) play crucial roles in teleost mucosal surface defenses, but their mucosal immune responses, especially under different routes of vaccine administration, needs to be better clarified. In the present study, the flounder (Paralichthys olivaceus) was immunized with inactivated Vibrio anguillarum by intraperitoneal injection and immersion, and pIgR and IgM responses were analyzed. Real-time PCR showed that pIgR and IgM mRNA expression were up-regulated with a similar variation trend, but pIgR mRNA responded earlier than IgM; the pIgR mRNA levels were higher in spleen, gills, skin and hindgut in both immunized groups, while IgM mRNA response was higher in skin, gills, hindgut and liver in immersion group, or head kidney, spleen, hindgut and liver in injection group. Immunohistochemical results revealed that pIgR and IgM were localized in the epithelium of skin, gills and hindgut, and biliary epithelium of liver. Western blot demonstrated that a ~800 kDa protein band in skin, gill and gut mucus and bile reacted with anti-pIgR and anti-IgM antibody, indicating that secretory component (SC) of pIgR associated with polymeric IgM as a complex in these secretions. ELISA assay revealed that the vaccine-specific IgM and SC of pIgR levels were up-regulated in skin, gill and gut mucus and bile, reaching a higher peak level at earlier time in skin and gill mucus in immersion than injection group, and a higher peak level in bile and gut mucus in injection group. These results illustrated that immersion and injection vaccination stimulated pIgR and secretory IgM production in mucus and bile, and a disparity in pIgR and IgM response was observed under different administration routes, which provided better understanding for fish mucosal immunity and in turn helped to develop vaccination strategies aimed at maximizing mucosal and consequently fish health. •pIgR and IgM expression were up-regulated by inactivated Vibrio anguillarum.•pIgR response was earlier than IgM at mRNA and protein levels after vaccination.•pIgR and IgM were localized in epithelium of skin, gills and hindgut and biliary epithelium of liver.•pIgR (SC)-tetrameric IgM complexes existed in skin, gut and gill mucus and bile but not in serum.•A disparity in pIgR and IgM response was observed under different administration routes.