Cyprinus carpio slc15a1 gene is a low-affinity, high-volume transporter of small peptides and peptide analogs into various tissue cells using a proton gradient inverse concentration, and this gene also plays an important role in the immune response. To investigate the changes of slc15a1 (slc15a1a and slc15a1b) genes in the immune response mechanism in carp at the protein level, the fragments of slc15a1a and slc15a1b genes containing part of the antigenic determinant cluster were ligated to pET-32a(+) by adding the double digestion sites BamH Ⅰ and Hind Ⅲ, and the corresponding expression vectors were constructed, and polyclonal antibodies to slc15a1a and slc15a1b genes were successfully prepared. The potency of the antibody was detected by ELISA, and the potency of mouse anti-Slc15a1a and Slc15a1b obtained were 8.1×10⁵ and 2.7×10⁵. When infected by Aeromonas hydrophila, the highest protein expression levels of Slc15a1a and Slc15a1b increased 3.39 and 2.85-fold, respectively, compared with the blank control, indicating that the polyclonal antibodies prepared in this experiment have high affinity and specificity and exhibit strong immunogenicity, which can promptly induce an immune response in the organism. Slc15a1a responded rapidly with high expression at 3 h and 6 h after A. hydrophila infection and began to show a decrease in expression level after 12 h, but Slc15a1b maintained a more stable high expression response between 3 h and 24 h, indicating a certain expression difference between Slc15a1a and Slc15a1b. During infection, the expression of Slc15a1a was largely higher than that of Slc15a1b, so the slc15a1a gene may be the major gene of the slc15a1 gene and may play an important role in the common carp immune response process.