HRVs and HEVs are characterized by ≈100 serotypes. Recently, molecular diagnostic tools have shown that this diversity expands beyond those predefi ned serotypes and encompasses also previously unrecognized rhinovirus and enterovirus genotypes. As an example, a new HRV lineage named HRV-C was recently identifi ed and now complements the 2 previously known A and B lineages (6-8) (N.J. Knowles, pers. comm.). The C lineage has not only a distinct phylogeny (9) (10) (11) (12) (13) (14) (15) (16) but is also characterized by specifi c cis-acting RNA structures (17) .