Involvement of formyl peptide receptor 2 in canine coronavirus infection: in vitro and in Silico approaches

Canine coronavirus type II (CCoV-II), an alphacoronavirus, is responsible for mild enteritis, especially in puppies, but due to its plasticity, it can also cause serious diseases in humans. Formyl peptide receptors (FPRs) play an important role in modulating immune responses, and their expression is variably regulated by cell type and by viral infections. In this study, the role of FPR2 during CCoV infection in a canine fibrosarcoma (A72 cells) cell line as well as in a feline Crandell-Rees Feline Kidney (CRFK) cell line was investigated by in vitro and in silico approaches. During infection, in the presence of WRW4, a specific FPR2 inhibitor, a reduction in gene and protein levels of FPR2 in CCoV infected cells was observed. These results were accompanied by worsened changes in cell viability and morphology in the treated-infected groups, which exhibited substantial growth in virus yield and a significant increase in both gene and protein expression of viral nucleocapsid protein (NP). Interestingly, an opposite trend in the above assays was observed following infection with HP2-20, an agonist of FPR2. The 3D model of canine FPR2 (cFPR2) showed that WRW4 was confined to the cFPR2 core and did not interact with the extramembrane loops of the receptor, whereas HP2-20 contacted both the core and the second extracellular loop of cFPR2 (ECL2). In addition, the complex cFPR2/HP2-20 exhibited a marked increase in the number of H-bonds, hydrophobic interactions and electrostatic charges compared to the complex cFPR2/WRW4. In conclusion, these results showed that CCoV replication is related to FPR2, suggesting it as an interesting target to develop new drugs to fight CoVs infection.