Human astroviruses: in silico analysis of the untranslated region and putative binding sites of cellular proteins.

Human astrovirus (HAstV) constitutes a major cause of acute gastroenteritis in children. The viral 5' and 3' untranslated regions (UTR) have been involved in the regulation of several molecular mechanisms. However, in astrovirues have been less characterized. Here, we analyzed the secondary structures of the 5' and 3' UTR of HAstV, as well as their putative target sites that might be recognized by cellular factors. To our knowledge, this is the first bioinformatic analysis that predicts the HAstV 5' UTR secondary structure. The analysis showed that both the UTR sequence and secondary structure are highly conserved in all HAstVs analyzed, suggesting their regulatory role of viral activities. Notably, the UTRs of HAstVs contain putative binding sites for the serine/arginine-rich factors SRSF2, SRSF5, SRSF6, SRSF3, and the multifunctional hnRNPE2 protein. More importantly, putative binding sites for PTB were localized in single-stranded RNA sequences, while hnRNPE2 sites were localized in double-stranded sequence of the HAstV 5' and 3' UTR structures. These analyses suggest that the combination of SRSF proteins, hnRNPE2 and PTB described here could be involved in the maintenance of the secondary structure of the HAstVs, possibly allowing the recruitment of the replication complex that selects and recruits viral RNA replication templates.