Objective: To evaluate the cross-reaction of seasonal influenza vaccine immune serum against Eurasian avian-like H1N1 swine influenza virus. Methods: Nine human infected Eurasian avian-like H1N1 swine influenza virus strains were obtained from national influenza surveillance network laboratories in Jiangsu, Hebei, Shandong, Yunnan, Hunan, Fujian and Tianjin provinces, and their genetic characteristics of hemagglutinin were analyzed by deep sequencing. 30 volunteers were recruited respectively from children (2-5 years old), adults (24-57 years old) and elderly (60-84 years old) who received 2019-2020 seasonal influenza vaccine in Anning city, Yunnan Province in October 2019, and serum samples were collected before and 1 month after vaccination. The hemagglutination inhibition test was used to evaluate the cross-reaction of serum before and after immunization against 4 strains of human infection with Eurasian avian-like H1N1 swine influenza virus isolated since 2015. Results: The homology of hemagglutinin genes of 9 Eurasian avian-like H1N1 swine influenza viruses was similar, but the difference of hemagglutinin heavy chain and light chain amino acid genes with A (H1N1) pdm09 (vaccine strain) were 90-101 and 24-30 amino acids respectively. The antibody titer of vaccine strain antiserum to vaccine strain was 2 560; the antibody titers of the vaccine strain antiserum to Eurasian avian-like H1N1 swine influenza virus and the Eurasian avian-like H1N1 swine influenza virus antiserum to vaccine strain were same as 640. The proportion of children, adults and elderly vaccinated with seasonal influenza vaccine with antibody titer ≥40 against vaccine strain was 90.0%, 70.0% and 73.3%, respectively; while the proportion merely were 46.7%, 36.7% and 33.3%-43.3% to 4 strains of Eurasian avian-like H1N1 swine influenza virus, respectively. Conclusion: Seasonal influenza vaccination does not provide effective cross-protection against Eurasian avian-like H1N1 swine influenza virus.
目的： 评估季节性流感疫苗免疫血清对欧亚类禽H1N1猪流感病毒的交叉反应。 方法： 9株人感染欧亚类禽H1N1猪流感病毒株来自江苏、河北、山东、云南、湖南、福建和天津等省份的国家级流感监测网络实验室，通过深度测序分析其血凝素特性。于2019年10月在云南省安宁市接种2019-2020年度季节性流感疫苗的儿童（2~5岁）、成人（24~57岁）和老年人（60~84岁）中各招募30名志愿者，采集其接种疫苗前和接种1个月后血清。通过血凝抑制试验评估免疫前后血清对2015年以来分离的4株人感染欧亚类禽H1N1猪流感病毒的交叉反应。 结果： 9株欧亚类禽H1N1猪流感病毒的血凝素基因同源性较一致，但与甲型流感病毒［A（H1N1）pdm09］（以下简称“疫苗株”）的血凝素重链和轻链氨基酸基因的差异分别为90~101个和24~30个氨基酸。疫苗株抗血清对疫苗株的抗体滴度为2 560，欧亚类禽H1N1猪流感病毒以及欧亚类禽H1N1猪流感病毒抗血清对疫苗株的抗体滴度均为640。接种季节性流感疫苗的儿童、成人和老年组人群针对疫苗株的抗体滴度≥40者占比分别为90.0%、70.0%和73.3%；而对4株欧亚类禽H1N1猪流感病毒仅为46.7%、36.7%和33.3%~43.3%。 结论： 接种季节性流感疫苗不能对欧亚类禽H1N1猪流感病毒产生有效的交叉保护作用。.