Sequence variation within the capsid protein of Australian isolates of feline calicivirus

The capsid protein of Australian feline calicivirus (FCV) isolates is demon strably different from the prototype strain F9. Five Australian isolates of FCV, dating from 1970 to 1989, were analysed by western blotting and immun oprecipitation. Varying reactivity to a panel of F9 specific monoclonal ant ibodies (MAbs) was observed. DNA sequencing of RT-PCR generated clones supp orted the observation of variation between capsid proteins. Predicted amino acid sequences varied by 11 to 17.5% across the whole capsid when compared to the published F9 sequence. Differences in amino acid sequence were most apparent in previously described hypervariable regions (C and E). Within h ypervariable region E differences of 22 to 34% were observed compared to F9 . The observed lack of reactivity to F9 MAbs correlated with amino acid cha nges within previously characterized binding sites within region E. (C) 199 4 Elsevier Science B.V. All rights reserved.