During our genomic analysis we found HRV A2 strains shared only 50%-53% average amino acid sequence identity with other HRV strains ( Figure 1) ; less with any strain from an HEV species. Average HRV A2 G+C content (42.4%) fell between the rhinovirus (38.7%) and enterovirus (45.6%) genera, suggesting an intermediate evolutionary path for HRV A2 strains. Nonetheless, a large number of HRV motifs, including those recognized by the RNA-dependent RNA polymerase, were retained by HRV A2 strains. This supported the proposal that some HRV genomic regions are under purifying selection [26] , even among the newly identified and divergent strains. HRV A2 strains were most similar to the HRV As overall, but amino acid sequences were as different from any traditional HRV or HEV species as the species in those genera were from each other. Previous subgenomic HRV A2 nucleotide phylogenies [31] [32] [33] were confirmed and expanded herein reinforcing that these NIVs reside within a distinct clade of the genus Rhinovirus, branching from the existing HRV A species ( Figure 6 ). The inability to propagate an HRV A2 virus could be due to many factors including the age, storage, site of origin and amount of the inoculum, its handling during processing, how long after symptoms appear before sampling occurs and the culture conditions used. It is also possible that an unknown primary receptor is employed or that binding of a secondary receptor is required for successful viral attachment and entry; or a mix of both. We sought to approach receptor-related issues using homology models derived crystallography data which already exist for a small number of HRV strains. Models of the component structural proteins from the prototypical HRV A2 strain, HRV-QPM, predicted that the characteristic 'jellyroll' conformations were retained (Figure 2 ) despite frequent and distinguishing deletions and inter-and intra-genus diversity at the sites of receptor contact and antigenicity (Figure 3 ). This also supported findings that HRV variability is mostly localized to receptor and antigenic sites [24, 33, 45] and begins to extend the data to include the more divergent strains.