Use of Shotgun Immunoproteomics for the Development of Protein Vaccines against Edwardsiella piscicida

Authors: JACOBSEN, KIM - University Of California, Davis; GRIFFIN, MATT - Mississippi State University; PHINNEY, BRETT - University Of California, Davis; SALEMI, MICHELLE - University Of California, Davis; YAZDI, ZEINAB - University Of California, Davis; BALAMI, SUJITA - Mississippi State University; Older, Caitlin; WARE, CYNTHIA - Mississippi State University; YAMAMOTO, FERNANDO - Mississippi State University; UI-HUDA, NOOR - Mississippi State University; RODRIGUEZ-RAMOS, TANIA - University Of Waterloo; DIXON, BRIAN - University Of Waterloo; Ma, Jie; Lafrentz, Benjamin; SOTO, ESTEBAN - University Of California, Davis

Submitted to: Fish and Shellfish Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2025
Publication Date: 11/8/2025
Citation: Jacobsen, K.L., Griffin, M., Phinney, B.S., Salemi, M., Yazdi, Z., Balami, S., Older, C.E., Ware, C.C., Yamamoto, F.Y., Ui-Huda, N., Rodriguez-Ramos, T., Dixon, B., Ma, J., Lafrentz, B.R., Soto, E. 2025. Use of Shotgun Immunoproteomics for the Development of Protein Vaccines against Edwardsiella piscicida. Fish and Shellfish Immunology. 168:110992. https://doi.org/10.1016/j.fsi.2025.110992.
DOI: https://doi.org/10.1016/j.fsi.2025.110992

Interpretive Summary: Edwardsiella piscicida is an important emerging bacterial pathogen for various cultured fish species, including catfish and trout. Researchers at the University of California Davis in collaboration with scientists from Mississippi State University, USDA ARS WARU, the University of Waterloo, and USDA ARS AAHRU used shotgun immunoproteomics, a method for predicting vaccine targets based on the pathogen genome, to identify E. piscicida proteins that could be used for vaccines to protect cultured fish. Serum samples from rainbow trout and catfish hybrids allowed for the identification of 36 vaccine candidate E. piscicida proteins; three proteins (GroEL, COPIII, GlyZip) were tested as oral and injected vaccines. Immunization of fish and subsequent laboratory experiments indicated injection of COPIII and GlyZip vaccines led to slightly improved survival. Fish injected with any of the vaccines generated a strong antibody response against the protein they were immunized with. Two proteins, GroEL and GlyZip, elicited strong antibody responses in sham-vaccinated (no bacterial protein) fish when challenged with E. piscicida. These results provide evidence of the value of shotgun immunoproteomics for candidate vaccine target discovery, and identified potential vaccine targets for further development.

Technical Abstract: Edwardsiella piscicida is an important emerging pathogen in various cultured fish species. This study aimed to identify immunogenic E. piscicida proteins and evaluate these antigens as protein vaccines for use in aquaculture. Shotgun immunoproteomics using anti-E. piscicida serum from rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) × blue catfish (Ictalurus furcatus) hybrids inoculated with formalin-killed whole-bacteria preparations identified 36 candidate immunogenic E. piscicida proteins. The chaparonin GroEL, the glycine 2TM zipper domain-containing protein (GlyZip), and coproporphyrinogen-III oxidase (COPIII) were used to orally (PO) and intra-coelomically (IC) immunize Chinook salmon (Oncorhynchus tshawytscha). Fish IC vaccinated with either GlyZip or COPIII demonstrated a slight, but non-significant, improvement in survival post-challenge with E. piscicida S11-285. Surprisingly, fish IC or PO vaccinated with GroEL displayed an antiprotective effect (RPS = -184% and RPS=76%, respectively) against subsequent challenge. All IC vaccinated fish generated a strong specific antibody response against the immunizing protein, and sham vaccinated fish challenged with E. piscicida S11-285 generated a significantly higher specific antibody response to the GroEL and GlyZip proteins than negative control fish, suggesting that shotgun immunoproteomics was effective for detection of immunogenic bacterial proteins that can stimulate humoral immune responses in the host fish.