Resistant and susceptible rainbow trout (Oncorhynchus mykiss) lines show distinctive immune response to Lactococcus garvieae.

摘要: Abstract Lactococcosis is one of the main bacterial diseases affecting rainbow trout (Oncorhynchus mykiss), with significant economic and sanitary repercussion. Vaccination antibiotic treatments are commonly used to prevent control infection outbreaks; however, these strategies have some drawbacks including limited coverage, handling costs, induction resistance chemical residues in environment. Selective breeding programs represent a promising complementary approach for increasing fish disease commercial farms immunological parameters may be tentatively as indirect indicators this purpose. The present study investigated first time innate adaptive immune responses two groups derived from selected lines (susceptible resistant) showing different “in field” phenotypical Yersinia ruckeri, Flavobacterium branchiophilum, F. psychrophilum, Ichthyophthirius multifiliis, after an immersion-dilution based exposure Lactococcus garvieae carried out controlled experimental conditions. Twenty-six resistant twenty-six susceptible female (mean body weight 80 g, 9 months aged, F5 generation) were obtained intensive farm considered L. free exposed pathogen. Moreover, 10 uninfected controls. After 5 days, blood tissue samples collected analyses. A significantly higher serum mucus lysozyme activity was recorded compared (P ≤ 0.05), both before garvieae. Similarly, respiratory burst head kidney leukocytes resulted more intense suggesting that phagocytes could quickly activate their microbicidal mechanisms counteract spread. Resistant group displayed also up-regulation immunoglobulins M (IgM), major histocompatibility complex II (MHC-II) interleukin 8 (IL-8) gene expression (P ≤ 0.05) lymphocytes count highlighting potential better ability trigger recruitment defensive cells initiation specific processes such antigen presentation CD4+ T IgM synthesis. results herein presented might useful identification markers selective programs.