Molecular epidemiological analysis of echovirus 19 isolated from an outbreak associated with hand, foot, and mouth disease (HFMD) in Shandong Province of China.

Objective: To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 (E19) isolates collected from an outbreak associated with hand, foot and mouth disease (HFMD) in Tai'an city of Shandong Province of China from July to September, 2003.

Methods: Thirty seven Echovirus 19 isolates were isolated from stool specimens and throat swabs collected during the outbreak, then major capsid (VP1) genomic sequence was determined, and phylogenetic tree was done based on the VP1 sequences among these 37 and other E19 viruses deposited in the Genbank. Also a representative strain named CHN-SD03-TN12 was selected for sequencing of 5'-untranslated regions (5'-UTR).

Results: The identity rate was about 98.9%-100% among all these 37 E19 viruses. The genetic relationships between these 37 E19 isolates and other strains reported were also depicted. The identity rate was about 78.4%-78.9% compared with E19 reference strain Burke. The substitutions in the sequence of 5'-UTR resulted in changes in the conjectural properties of 5'-UTR of E19 viruses.

Conclusion: The genetic features of E19 viruses isolated during the outbreak in Shandong Province in 2003 may be associated with a genetic and antigenic drift that changes the virulence of the Shandong isolates, but the molecular changes in Shandong E19 viruses contributing to their phenotype remain to be further illuminated. However, the sequences described in this paper substantiate the changes taken place in capsid VP1 and 5'UTR regions. These substitutions may contribute to their tropism and virulence, and play a significant role in pathogenesis and clinical manifestations of the disease.