Sex-specific disease resistance and gut microbiota dynamics in juvenile common carp (Cyprinus carpio) following viral infection

Sex-specific differences in disease resistance are well-documented in vertebrates, with immune responses often influenced by sex hormones and other physiological factors. However, the relationship between gut microbiota and immunity in driving these differences is not fully understood, particularly in non-mammalian vertebrates such as teleost fish. This study explores the role of sexual dimorphism in gut immunity and microbiota dynamics in juvenile common carp ( Cyprinus carpio ) following infection with the spring viremia of carp virus (SVCV). Using transcriptomic analysis and 16S rRNA sequencing, we assessed gut microbiota and immune responses in male, female, and all-female carps. Females exhibited heightened antiviral and inflammatory responses, which were associated with significant bacterial translocation and microbial dysbiosis. In contrast, males showed greater disease resistance and maintained a more stable gut microbiota. These results emphasize a significant correlation between changes in gut microbiota and sex-specific immune responses and provide valuable insights into the mechanisms underlying immunological dimorphism in teleost fish. These findings have important implications for improving aquaculture management and developing targeted disease control strategies. • Sex-specific differences in gut immunity and microbiota influence disease resistance in juvenile carp. • Male carp display weakened immune responses but have increased survival rates post-infection. • The gut microbiota dysbiosis induced by viral infection leads to robust immune activation in all-females and female carp.