3.3 Laboratory results
From 75 nasopharyngeal swab specimens collected in the outbreak, 14 samples were positive for HAdV-DNA. Nucleotide analysis of the sequences revealed that they were all HAdV7. Comparison of the nucleic acid sequences of all the 14 samples indicated that the isolates were 100% identical, which suggested that all isolates were derived from a common ancestor (HAdV7309-1B). Phylogenetic analysis of partial sequences was performed (Fig.1) and the results suggested that the strains belonged to HAdV7 and had high homology with the predominant HAdV7 strain (HAdV7 0901HZ/ShX/CHN/2009 GU230898), which was isolated in 2009 from Hanzhong, Shaanxi.11