Synthesis and evaluation of polyamine carbon quantum dots (CQDs) in Litopenaeus vannamei as a therapeutic agent against WSSV

Huai-Ting Huang,Chih-Ching Huang,John Han-You Lin,Hui-Ju Huang,Han-Jia Lin,Li-Li Chen

doi:10.1038/s41598-020-64325-5

Abstract

White spot syndrome virus (WSSV) is the causative agent of white spot syndrome (WSS), a disease that has led to severe mortality rates in cultured shrimp all over the world. The WSSV is a large, ellipsoid, enveloped double-stranded DNA virus with a wide host range among crustaceans. Currently, the main antiviral method is to block the receptor of the host cell membrane using recombinant viral proteins or virus antiserum. In addition to interference with the ligand-receptor binding, disrupting the structure of the virus envelope may also be a means to combat the viral infection. Carbon quantum dots (CQDs) are carbonaceous nanoparticles that have many advantageous characteristics, including small size, low cytotoxicity, cheap, and ease of production and modification. Polyamine-modified CQDs (polyamine CQDs) with strong antibacterial ability have been identified, previously. In this study, polyamine CQDs are shown to attach to the WSSV envelope and inhibit the virus infection, with a dose-dependent effect. The results also show that polyamine CQDs can upregulate several immune genes in shrimp and reduce the mortality upon WSSV infection. This is first study to identify that polyamine CQDs could against the virus. These results, indeed, provide a direction to develop effective antiviral strategies or therapeutic methods using polyamine CQDs in aquaculture.

Highlights

Several pathogens cause illness even death in shrimp
The results showed that the level of prophenoloxidase gene expression in shrimp treated with the 10 ppm polyamine Carbon quantum dots (CQDs)-containing feed group was not higher than the 1 ppm polyamine CQDs-containing feed group
The results showed that the LvToll gene in shrimp was upregulated after being fed the polyamine CQDs-containing feed, and the gene expression level in the 10 ppm polyamine CQDs-containing feed group was higher than in the 1 ppm polyamine CQDs-containing feed group (Fig. 7)

Summary

Materials and Methods

Throughout the acclimatization and experimental period, shrimp were fed twice daily with commercial shrimp feed, with or without the addition of polyamine CQDs. The temperature and salinity conditions of water were maintained at 25 ± 1 °C and at 34 ± 1‰. The polyamine CQDs solution was mixed with the feed and incubated at room temperature for 15 min. Shrimp were fed twice daily with commercial shrimp feed or polyamine CQDs-containing feed. For group 1 or group 2, the shrimp were fed with commercial shrimp feed or 10 ppm polyamine CQDs-containing feed for 7 days, and infected with WSSV using infected shrimp meat. During the acclimatization and experimental period, shrimp were fed twice daily with commercial shrimp feed or polyamine CQDs-containing feed. The mortality rates were subjected to paired sample t-tests

Result

Findings

Discussion