The Effect of <i>Houttuynia cordata</i> Feeding on the Expression of Anti-SVCV Inflammatory Factors in Common Carp

Spring viremia of carp virus (SVCV), a negative-sense single-stranded RNA virus belonging to the genus Sprivivirus in the family Rhabdoviridae, poses a significant threat to carp aquaculture due to its high virulence. Currently, there are no specific therapeutic drugs available for this pathogen. Driven by the concept of sustainable development in green fisheries, developing environmentally friendly antiviral agents has become a hot topic in the industry. This study systematically evaluated the effects of Houttuynia cordata Thunb., a plant with broad-spectrum pharmacological activity. It is used in both food and medicine for its immune regulation and antiviral capabilities. In this experiment, 30 healthy common carp ( Cyprinus carpio , with a body weight of 20 ± 5 g) were randomly divided into an experimental group (fed with feed containing 3% Houttuynia cordata extract) and a control group (fed with regular feed). After three weeks of feeding, a challenge experiment was conducted. Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) detected that the mRNA expression levels of key inflammatory factors, such as IL-10 and TNF-α, were significantly upregulated in the experimental group compared to the control group (p&lt;0.01). In contrast, the relative expression levels of NF-κB varied across various tissues. This study clarifies the molecular mechanism by which Houttuynia cordata extract enhances the innate immune response of common carp by promoting anti-inflammatory factors. It provides crucial experimental evidence for developing SVCV-resistant agents based on plant-derived active components, supporting green and sustainable aquaculture practices.