Abstract
The full‐length infectious cDNA clone was constructed and sequenced from the strain DM of echovirus 9, which was recently isolated from a 6‐week‐old child at the clinical onset of type 1 diabetes. Parallel with the isolate DM, the full‐length infectious cDNA clone of the prototype strain echovirus 9 Barty (Barty‐INF), was constructed and sequenced. Genetic relationships of the sequenced echo 9 viruses to the other members of the human enterovirus type B species were studied by phylogenetic analyses. Comparison of capsid protein sequences showed that the isolate DM was closely related to both prototype strains: Hill and Barty‐INF. The only exception was the inner capsid protein VP4 where serotype specificity was not evident and the isolate DM clustered with the strain Hill and the strain Barty‐INF with echovirus 30 Bastianni. Likewise, the nonstructural protein coding region, P2P3, of isolate DM was more similar to strain Hill than to strain Barty‐INF. However, like echovirus 9 Barty, the isolate DM contained the RGD‐motif in the carboxy terminus of capsid protein VP1. By blocking experiments using an RGD‐containing peptide and a polyclonal rabbit antiserum to the α~v~β~3~‐integrin, it was shown that this molecule works as a cellular receptor for isolate DM. By using primary human islets, it was shown that the isolate DM is capable of infecting insulin‐producing β‐cells like the corresponding prototype strains did. However, only isolate DM was clearly cytolytic for β‐cells. The infectious clones that were made allow further investigations of the molecular features responsible for the diabetogenicity of the isolate DM. J. Med. Virol. 69:529–537, 2003. © 2003 Wiley‐Liss, Inc.