Spike Protein Fusion Peptide and Feline Coronavirus Virulence

Coronaviruses are well known for their potential to change their host or tissue tropism, resulting in unpredictable new diseases and changes in pathogenicity; severe acute respiratory syndrome and feline coronaviruses, respectively, are the most recognized examples.Feline coronaviruses occur as 2 pathotypes: nonvirulent feline enteric coronaviruses (FECVs), which replicate in intestinal epithelium cells, and lethal feline infectious peritonitis viruses (FIPVs), which replicate in macrophages.Evidence indicates that FIPV originates from FECV by mutation, but consistent distinguishing differences have not been established.We sequenced the full genome of 11 viruses of each pathotype and then focused on the single most distinctive site by additionally sequencing hundreds of viruses in that region.As a result, we identifi ed 2 alternative amino acid differences in the putative fusion peptide of the spike protein that together distinguish FIPV from FECV in >95% of cases.By these and perhaps other mutations, the virus apparently acquires its macrophage tropism and spreads systemically.C oronaviruses (subfamily Coronavirinae, order Nido- virales) are enveloped, plus-strand RNA viruses that infect mammals and birds.They are quite common and cause infections in humans and a wide variety of animals; infection typically results in respiratory or enteric disease.Severe acute respiratory syndrome coronavirus (SARS-CoV), which emerged suddenly in 2002 and caused severe acute respiratory disease in humans, is the most notorious coronavirus.SARS-CoV spread rapidly around the globe, infecting thousands and killing ≈800 persons.The virus Spike Protein Fusion Peptide and Feline Coronavirus Virulence