Identification of adenovirus epidemic strains and analysis of hexon gene characteristics in Anqing area from 2013 to 2015

Abstract

Objective To investigate the characteristics of human adenovirus (HAdv) epidemic strains and the variations of hexon protein and amino acid residues in acute respiratory infections in Anqing. Methods A total of 596 throat swab samples of children with acute respiratory infections were collected from influenza surveillance sites between 2013 and 2015 and detected with real-time fluorescent PCR adenovirus nucleic acid test kit. Hep cells were used to separate viruses from positive samples. PCR amplification of hexon gene and sequencing analysis were conducted. Homologous alignment and phylogenetic tree analysis were performed between the obtained sequences and those published in GenBank. Results HAdv-positive samples accounted for 11.4% (68). Thirty-four viruses were successfully isolated, including nine HAdv-3 (26.5%), 12 HAdv-7 (35.3%), 12 HAdv-14 (35.3%) and one HAdv-55 (2.9%). The 9 strains of HAdv-3 had a close genetic relationship with KX384958, sharing a homology of 99.8%-100%. Three mutations in main amino acid residues were found in them as compared with reference strains. The 12 strains of HAdv-7 were genetically related to KX897164 and KU361344 with a homology ranging from 99.8% to 100% and had seven major amino acid residue mutations in comparison to reference strains. The 12 strains of HAdv-14 were highly similar to JF420883 with a homology of 99.6%-99.9%, and possessed three major variations in amino acid residues in comparison to reference strains. The HAdv-55 strain was closely related to KP279748 and KX289874, showing a homology of 100% in both nucleotide and amino acid sequences. HAdv-7 strains had the greatest variations, followed by HAdv-14 strains. Conclusion From 2013 to 2015, the epidemic adenovirus strains causing acute respiratory infections in Anqing area were mainly HAdv-3, HAdv-7 and HAdv-14 with a small number of HAdv-55. The hexon genes of HAdv-55 strains were stable and no variation occurred. However, HAdv-3, HAdv-7 and HAdv-14 strains all had some variations in nucleotides and amino acids. Amino acid variations in the antigenic determinants of HVR1, HVR2 and HVR7 regions were detected. Key words: Acute respiratory infection; Adenovirus; Hexon