Salmonid Rickettsial Septicemia (SRS) disease dynamics and Atlantic salmon immune response to Piscirickettsia salmonis LF-89 and EM-90 co-infection

• DOI: 10.1186/s13567-024-01356-0
• Publication Date: 2024-08-16T10:02:24Z
• Authors: Gabriela Carril; Byron Morales-Lange; Marie Løvoll; Makoto Inami; Hanne C. Winther-...; Margareth Øverland; Henning Sørum
• Keywords: Piscirickettsia; 570; 0303 health sciences; Coinfection; Veterinary medicine; bacterial load; Salmo salar; immune-related biomarkers; Piscirickettsiosis; Fish Diseases; 03 medical and health sciences; Piscirickettsiaceae Infections; Sepsis; SF600-1100; pathogenicity; Animals; bacterial intracellular pathogen; Chile; Research Article

Abstract In Chile, Piscirickettsia salmonis contains two genetically isolated genogroups, LF-89 and EM-90. However, the impact of a potential co-infection with these variants on Salmonid Rickettsial Septicemia (SRS) in Atlantic salmon ( Salmo salar ) remains largely unexplored. our study, we evaluated effect P. LF-89-like EM-90-like post-smolt after an intraperitoneal challenge to compare changes disease dynamics host immune response. Co-infected fish had significantly lower survival rate (24.1%) at 21 days post-challenge (dpc), compared single-infected (40.3%). contrast, all survived. addition, co-infected presented higher presence clinical lesions than any fish. The gene expression immune-related biomarkers head kidney, spleen, liver showed that isolate induced up-regulation cytokines (e.g., il-1β , ifnγ il8 il10 ), antimicrobial peptides hepdicin pattern recognition receptors (PRRs), such as TLR5s . Furthermore, serum samples from fish, increase total IgM level was observed. Interestingly, specific against greater detection antigens infected (cross-reaction). These data provide evidence interactions can modulate SRS salmon, causing synergistic increases severity mortality Overall, this study contributes achieving better understanding population dynamics.