Objective: To investigate the molecular epidemiological characteristics of norovirus (NoV) among children with acute gastroenteritis in Tianjin in 2017.
Methods: A total of 758 stool specimens were collected from the children with acute gastroenteritis possibly caused by viral infection in Tianjin Children's Hospital between January and December, 2017. Quantitative real-time RT-PCR was used for primary screening of NoV, and conventional RT-PCR was used for gene amplification, sequencing and genotype identification of the VP1 region of capsid protein in positive specimens.
Results: Among the 758 specimens, 241 (31.8%) were found to have GII NoV. Sequencing of the VP1 region of capsid protein in positive specimens showed that among the 241 specimens with GII NoV, 69 (28.6%) had GII.4 subtype, 51 (21.2%) had GII.3 subtype, 24 (10.0%) had GII.2 subtype, and 18 (7.5%) had other subtypes. There was a significant difference in NoV detection rate between different age groups (P=0.018), and the 1- <4 years group had the highest NoV detection rate (37.3%). There was also a significant difference in NoV detection rate across seasons (P<0.001), and there was a highest NoV detection rate in winter (48.1%). Twenty-seven children (3.6%) had co-infections with NoV and rotavirus.
Conclusions: NoV is one of the major pathogens of the children with acute gastroenteritis from Tianjin in 2017. GII genotype, especially GII.4 subtype, is the prevalent strain. NoV infection is commonly seen in children less than 4 years and reaches the peak in winter. Some children are found to have co-infections with rotavirus.
目的: 了解2017年天津地区急性胃肠炎患儿诺如病毒（NoV）分子流行病学特征。
方法: 收集2017年1~12月天津市儿童医院疑似由病毒感染引起的急性胃肠炎患儿的粪便标本758份，采用荧光定量RT-PCR方法对NoV进行初筛，运用传统RT-PCR方法对阳性标本的衣壳蛋白VP1区进行基因扩增、基因测序和鉴定基因型别。
结果: 758份粪便标本中检出GⅡ型NoV 241份，阳性率为31.8%。对阳性标本进行衣壳蛋白VP1区测序，发现GⅡ型标本中以GⅡ.4亚型为主，占28.6%（69/241）；其次为GⅡ.3亚型，占21.2%（51/241）；GⅡ.2亚型占10.0%（24/241）；其他亚型占7.5%（18/241）。不同年龄组间NoV检出率差异有统计学意义（P=0.018），其中1~ < 4岁组阳性检出率最高（37.3%）。不同季节的NoV检出率差异具有统计学意义（P < 0.001），其中冬季为高发季节（48.1%）。27份（3.6%）标本存在NoV和轮状病毒（RtV）的混合感染。
结论: NoV是2017年天津地区该组急性胃肠炎患儿的主要病原体之一；GⅡ基因型特别是GⅡ.4亚型是流行优势毒株；NoV感染在4岁内儿童更为常见；冬季为流行高峰；存在与RtV混合感染的情况。