In the peak mortality period of carp in the four groups (30 days post-infection), the expression levels of <i>IL21R</i>, <i>IRF9</i>, <i>LC3</i>, and <i>IFN-I</i> were significantly the highest in the M group and significantly the lowest in the Y group, with the mRNA expression of these genes in the M × Y group being significantly higher than that in the Y × M group (<i>p</i> < 0.05). This evidence concerns the gene IRF9 and infection.