Enhancing Pacific white shrimp immunity against through β-glucan supplementation from marine diatoms.

BACKGROUND AND AIM

Pacific white shrimp () is a principal species in global aquaculture. However, outbreaks of , the etiological agent of acute hepatopancreatic necrosis disease (AHPND), cause substantial economic losses. β-glucans derived from marine diatoms, (CH) and (TH), have shown potential as immunostimulants to enhance shrimp resistance to pathogenic infections. This study aimed to evaluate the effects of β-glucans derived from CH, TH, and their combination on growth performance, immune responses, and survival of and to elucidate the underlying molecular mechanisms through transcriptomic and gene silencing approaches.

MATERIALS AND METHODS

Juvenile shrimp were assigned to four dietary groups for 30 days: Control (β-glucan-free), β-glucan from CH, TH, and a mixture of both (CH and TH) (CHTH). Growth performance, total hemocyte count (THC), and survival rate were evaluated. RNA-seq was performed on hepatopancreas samples after 14 days to identify differentially expressed genes (DEGs). Key immune-related DEGs were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Functional analysis of the () gene was conducted through RNA interference (RNAi), followed by challenge.

RESULTS

The CHTH diet group exhibited significantly enhanced growth metrics and the highest survival rate. Transcriptomic analysis revealed 1,902 DEGs in the CHTH group compared to control, with 915 upregulated and 987 downregulated genes. qRT-PCR validated the expression trends of selected immune-related genes, notably , which showed robust upregulation. RNAi-mediated knockdown reduced survival upon bacterial challenge, confirming its role in β-glucan-induced immunity.

CONCLUSION

β-glucans derived from CH and TH, particularly in combination, significantly enhance growth performance and immunocompetence in . These findings underscore the potential of marine diatom-derived β-glucans as viable immunostimulants to mitigate AHPND in shrimp aquaculture, offering a sustainable alternative to antibiotic use.