MOLECULAR AND BIOLOGICAL CHARACTERISTICS OF ECHOVIRUS-22, - A REPRESENTATIVE OF A NEW PICORNAVIRUS GROUP

Recent sequence analysis revealed that the human pathogen echovirus 22 (EV22) is genetically distant from all the other picornaviruses studi ed to date (T. Hyypia, C. Horsnell, M. Maaronen, M. Khan, N. Kalkkinen , P. Auvinen, L. Kinnunen, and G. Stanway, Proc. Natl, Acad. Sci. USA 89:8847-8851, 1992). We have further characterized the biological prop erties of the virus and show here that the virion has properties simil ar to those of other picornaviruses. However, the protein composition is unique, in that most copies of one of the three major capsid protei ns, VPO, do not undergo the further processing to VP2 and VP4 observed during the maturation of the virus in previously studied picornavirus es. Alignment of the capsid protein sequences with those of other pico rnaviruses revealed, furthermore, that the VP3 polypeptide contains an apparent insertion of approximately 25 amino acids at its amino termi nus. An arginine-glycine-aspartic acid (RGD) motif is found in VPI, an d by using synthetic peptides, it was shown that this sequence plays a role in cell surface receptor recognition. Finally, EV23 was shown to share remarkable identity with EV22 in certain parts of the genome an d also belongs to this previously unrecognized picornavirus group.