First Identification of Human Adenovirus Subtype 21a in China With MinION and Illumina Sequencers

Ye, Fuqiang; Han, Yifang; Zhu, Juanjuan; Li, Peng; Zhang, Qi; Lin, Yanfeng; Wang, Taiwu; Lv, Heng; Wang, Changjun; Wang, Chunhui; Zhang, Jinhai

Since the first discovery by Rowe et al. (1953) , human adenoviruses (HAdVs) have been found to cause a diversity of diseases in children and adults (Radke and Cook, 2018; Prusinkiewicz and Mymryk, 2019; Yao et al., 2019) . Belonging to the Mastadenovirus genus in the Adenoviridae family, HAdVs are double-stranded DNA viruses with 35-36 kb pairs in their genomes (Radke and Cook, 2018) . At present, almost 90 Adv subtypes distributed across seven species (termed as A through G) have been classified, among which 55 could lead to human infections (Prusinkiewicz and Mymryk, 2019; Yao et al., 2019) . A variety of tissue tropisms are observed in these HAdVs, with preferred infections of species B/C/E in the respiratory tracts, species B/C/D/E in the conjunctiva, species A/F/G in the gastrointestinal tract, and species B in the kidney (Lenaerts et al., 2008; Lion, 2014; Prusinkiewicz and Mymryk, 2019) . Human adenovirus types 3, 4, 7, 11, 14, 21 , and 55 are common AdV pathogens responsible for human respiratory tract infections or respiratory outbreaks in many regions (Lewis et al., 2009; Kajon et al., 2010; Li et al., 2014; Scott et al., 2016; Bautista-Gogel et al., 2019; Prusinkiewicz and Mymryk, 2019; Sammons et al., 2019; Zhang et al., 2019) . Clinical symptoms caused by HAdVs are usually mild and self-limiting in healthy people; however, immunologically compromised individuals such as young children, elderly persons, and immunosuppressed patients might have a higher risk of severe disease and even death (Ison, 2006; Kandel et al., 2010; Lee et al., 2010; Scott et al., 2016; Pfortmueller et al., 2019) . Notably, HAdV-associated respiratory outbreaks are commonly seen in closed population clusters, including schools and hospitals (Scott et al., 2016; Radke and Cook, 2018) .