The RQ values of hampa, frrs1a, il8a, timp2b, campb, tlr5a, ifng, ch25ha, il1b, pstpip2a, bcl10a, saa5, tapbp, card9, ncf2, hmox1a, alox12, aifm2 and c3a were positively correlated with the infection level, whereas sesn1a, pgds, selenopb, gsn, ftm and tra showed significant negative correlations with the expression level of P. salmonis ITS. The gene discussed is AIFM2; the disease is infection.