Glycyrrhiza polysaccharide inhibits feline infectious peritonitis virus infection screened by a recombinant virus expressing eGFP protein

Feline infectious peritonitis (FIP) is a fatal infectious disease caused by feline infectious peritonitis virus (FIPV) which causes death of young cats less than 2 years old. Until now, few drugs are available for treatment of FIP. Here, we developed a modified FIPV expressing e GFP reporter gene by reverse genetics to evaluate the ability of Chinese herbal polysaccharides on inhibition of FIPV infection in Crandell-Rees feline kidney (CRFK) cells. The results demonstrated that the recombinant FIPV could express eGFP reporter gene, replicated in the CRFK cells and grow in a similar way with wild-type FIPV. By using this recombinant FIPV, we found that glycyrrhiza polysaccharide (GPS) effectively inhibited FIPV when added at the same time with virus or post-infection in CRFK cells. Further studies revealed that GPS inhibited FIPV adsorption and replication, but did not affect FIPV internalization in CRFK cells. In the current study, we successfully established a modified FIPV platform which supports high-throughput drug screening in vitro, and we found that GPS is a promising candidate for treating FIP.