Genetic Analysis of Human Adenovirus Type 7 Strains Circulating in Different Parts of China

To investigate the molecular epidemiology and genetic variation of human adenovirus type 7(HAdV-7)in children with acute respiratory infections(ARI)in China.HAdV-7-positive respiratory samples collected from children with ARI in Beijing,Shijiazhuang,Wenzhou and Guangzhou from 2014–2018 were selected for gene amplification and sequence analysis.Fifty-seven HAdV-7 clinical strains with hexon,penton base and fiber gene sequences were obtained.Meanwhile17 strains were selected randomly from different cities for whole genome sequencing.Phylogenetic and variation analyses were performed based on the obtained sequences,HAdV-7 prototype strain Gomen(AY594255),vaccine strains(AY495969 and AY594256)and representative sequences of strains.The phylogenetic trees constructed based on whole genome sequences,major capsid protein genes(hexon,penton base and fiber)and the early genes(E1,E2,E3 and E4)were not completely consistent.The HAdV-7 strains obtained in this study always clustered with most of the circulating strains worldwide from the 1980 s to the present.Compared with the HAdV-7 prototype strain Gomen(AY594255),some amino acid mutations in loop1 and loop2 of hexon and the RGD loop region of the penton base gene were observed.Recombination analysis showed that partial regions of 55 k Da protein and 100 kDa hexon-assembly associated protein genes among all HAdV-7 strains in this study were from HAdV-16 and HAdV-3,respectively.Our study demonstrated the molecular evolution characteristics of HAdV-7 strains circulating in China and provided basic reference data for the prevention,control and vaccine development of HAdV-7.

Analysis of severe human adenovirus infection outbreak in Guangdong Province,southern China in 2019

During 2018–2019,a severe human adenovirus(HAdV)infection outbreak occurred in southern China.Here,we screened 18 respiratory pathogens in 1704 children(≤14 years old)hospitalized with acute respiratory illness in Guangzhou,China,in 2019.In total,151 patients had positive HAdV test results;34.4%(52/151)of them exhibited severe illness.HAdV infection occurred throughout the year,with a peak in summer.The median patient age was 3.0(interquartile range:1.1–5.0)years.Patients with severe HAdV infection exhibited increases in12 clinical indexes(P≤0.019)and decreases in four indexes(P≤0.007),compared with patients exhibiting nonsevere infection.No significant differences were found in age or sex distribution according to HAdV infection severity(P>0.05);however,the distributions of comorbid disease and HAdV co-infection differed according to HAdV infection severity(P<0.05).The main epidemic types were HAdV-3(47.0%,71/151)and HAdV-7(46.4%,70/151).However,the severe illness rate was significantly higher in patients with HAdV-7(51.4%)than in patients with HAdV-3(19.7%)and other types of HAdV(20%)(P<0.001).Sequencing analysis of genomes/capsid genes of 13 HAdV-7 isolates revealed high similarity to previous Chinese isolates.A representative HAdV-7isolate exhibited a similar proliferation curve to the curve described for the epidemic HAdV-3 strain Guangzhou01(accession no.DQ099432)(P>0.05);the HAdV-7 isolate exhibited stronger virulence and infectivity,compared with HAdV-3(P<0.001).Overall,comorbid disease,HAdV co-infection,and high virulence and infectivity of HAdV-7 were critical risk factors for severe HAdV infection;these data can facilitate treatment,control,and prevention of HAdV infection.