HSPA4 and infection: The results showed that hsp70 (hspa1a), hspa1b, and hspa5 were all significantly or extremely significantly upregulated in the spleen and kidney tissues at 6, 12, 24, and 48 h post-infection with E. tarda, especially hsp70 (hspa1a) and hspa1b, indicating their crucial roles in response to biotic stress.