Horimoto T, Ito T, Alexander D J, Kawaoka Y
Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA.
J Vet Med Sci. 1995 Oct;57(5):927-30. doi: 10.1292/jvms.57.927.
An avian influenza virus, A/turkey/England/50-92/91 (H5N1), showed extremely high virulence in chickens, although its hemagglutinin (HA) cleavage site sequence (R-K-R-K-T-R), having a nonbasic (Thr) residue at the second position (P-2) from the carboxyl terminus of HA1, does not conform to the previously established consensus sequence motif, X-X-R/K-X-R/K-R (X = nonbasic residue), for highly virulent phenotype of the H5 virus. When we evaluated the HA cleavability of this strain in chicken embryo fibroblast culture, we observed that, unlike other HAs with a Thr residue at P-2, this HA was efficiently cleaved. These findings suggest that a nonbasic residue at the P-2 does not affect its recognition and catalyzation by cleavage enzymes that are otherwise influenced by steric structure around the cleavage site.
