Evaluation of the immune responses against enteric septicemia and determination of immune markers for selective breeding of pangasius families (Pangasianodon hypophthalmus)

Abstract

The immune response of two groups of selective breeding striped catfish families: susceptible (or sensitive) (S) and resistant (R) family groups, including red blood cell count (RBC count), white blood cell count (WBC count), neutrophil (NEU), monocytes (Mono), lymphocytes (LYM), and melano-macrophage centers (MMCs) count in liver, kidney and spleen tissue and antibody titers (ABT) against the bacteria Edwardsiella ictaluri were evaluated in this research. Fish were sampled at five truncated points after infection with the bacteria Edwardsiella ictaluri including before the challenge, 24, 48, 264, and 312 hpi. The immune response of the R group was more effective than that of the S group, showing: (1) RBC decreased less during the challenge; (2) WBC increased more rapidly, especially at the truncated point 24-48 hpi; (3) MMCs in liver, kidney, and spleen of the R group increased faster up to the truncated point 48 hpi while the S group increased more slowly and only up to the truncated point 24 hpi; (4) ABT were higher in all stages of the challenge. The research developed a multivariable logistic regression model with immune markers such as NEU, ABT and MMCs in liver at the truncated point 24-48 hpi to identify individuals which were resistant to Enteric Septicemia of Catfish (ESC), with sensitivity and specificity of 91.7, 95.0%, respectively.