Effect of starvation on the gut microbiota and intestine in gibel carp (Carassius gibelio) against Cyprinid herpesvirus-2 (CyHV-2) infection

Viral infections cause substantial economic losses in aquaculture, particularly in intensive aquaculture conditions. While short-term starvation naturally occurs in wild fish and post-infection scenarios, the impact of starvation on gut microbiota and the effect on the host's intestinal tissue after viral infection remains insufficiently understood. This study aimed to investigate the influence of starvation on gut microbial and intestinal tissue damage in Carassius gibelio (gibel carp) caused by Cyprinid herpesvirus-2 (CyHV-2) infection. Short-term starvation reduced gut microbiota diversity and induced distinct separation from the dietary state in healthy. Starvation increased Cetobacterium abundance and persisted post-infection while suppressing opportunistic pathogens such as Aeromonas, and maintained intestinal tissue integrity after CyHV-2 infection. Microbial correction network based on spearman correlation index revealed CyHV-2 infection increased microbiota complexity, whereas neutral modeling indicated short-term starvation moderated viral-induced deterministic shifts in microbial assembly process. Microbial community function demonstrated altered microbial metabolic profiles, including amino acid metabolism and chemotactic activity, under starvation and infection. We systematically characterize starvation on gut microbiota and find the protective effect of intestinal tissue after CyHV-2 infection. In conclusion, this study provides novel insights into the gut microbiota composition of gibel carp after starvation in healthy and CyHV-2 infection.