Epidemiology of human adenovirus and molecular characterization of human adenovirus 55 in China, 2009–2012

Lu, Qing-Bin; Tong, Yi-Gang; Wo, Ying; Wang, Hong-Yu; Liu, En-Mei; Gray, Gregory C; Liu, Wei; Cao, Wu-Chun

Human adenoviruses (HAdV) are a common cause of acute respiratory diseases, causing sporadic infections, as well as community and institutional outbreaks. 1 Infection with HAdV rarely causes serious or fatal illness in otherwise healthy individuals, but may cause severe disease in newborn, elderly, or immunocompromised persons. 1 There are at least 69 recognized HAdV genotypes (http://hadvwg.gmu.edu/), which are assigned to seven subgroups (A-G) according to biophysical, biochemical, and genetic characteristics. 2 The spectrum of clinical disease associated with HAdV is broad and depends largely upon the infecting HAdV genotype. Clinical signs and symptoms include fever, rhinorrhea, pharyngitis, conjunctivitis, gastroenteritis, bronchitis, pneumonia, acute hemorrhagic cystitis, meningoencephalitis, and rarely life-threatening disseminated diseases. 1 New adenovirus genotypes are increasingly recognized through the use of phylogenetic analysis based on complete genomic sequences. Novel strains may arise from mutations or recombinations of two different adenovirus strains between the hexon gene and fiber genes. 3, 4 Recently, an emergent variant, HAdV-55, 5, 6 with a proposed recombination of hexon gene between HAdV-11 and HAdV-14 strains, has been described in association with multiple outbreaks of acute respiratory disease, mostly occurring in military camps. [7] [8] [9] [10] In 2005, a large outbreak of acute respiratory disease likely from HAdV-55 occurred in a military camp in Turkey. 8 Another two HAdV-55 outbreaks occurred among military training camps in 2005 (226 patients in Singapore 9 ) and in 2009 (108 patients in China 10 ). Nucleotide sequence analysis showed the strains from the two outbreaks were highly similar to the QS-DLL strain, which was the first HAdV-55 in China isolated from an ARDS outbreak in Shaanxi in t 2006 that occurred in a senior high school. 7 The most recent HAdV-55 outbreak occurred in February 2012 among patients with febrile respiratory tract infection admitted to PLA 252 hospital, Hebei Province, China (unpublished data). With rare precedent circulation of HAdV-11 and HAdV-14 in China, an increasing trend of adenovirus type 55 infections was observed among both civilian and military populations, probably due to the lack of immunity herd. This concern, in combination with its higher tendency in causing severe respiratory illness than other adenovirus, posed great threats to Chinese military that it has the potential to spread widely and cause severe epidemics. The status highlights the need for improved surveillance, with extensive molecular characterization, to identify the prevalence and the genetic variants of this emerging adenovirus. Thus far, HAdV surveillance in China is sparse, and HAdV-55 infections were chiefly identified during outbreak events. The current study was sought to acquire a better understanding of the prevalence and molecular evolution of HAdV-55 strains by performing an active surveillance for HAdV infections. This knowledge might assist with targeted population for disease prevention and geographic regions where type-specific vaccines should be administered if developed.