Zhang Qin, Yang Xi-qiang, Zhao Xiao-dong
P2 Laboratory, Children's Hospital, Chongqing University of Medical Sciences, Chongqing 400014, China.
Zhonghua Er Ke Za Zhi. 2007 Jun;45(6):432-6.
Human metapneumovirus (hMPV) has been identified as one of the most important viral pathogens for acute respiratory tract infections in children. This study was to observe neutralizing activity to hMPV in sera collected from children without respiratory illnesses aged 0 to 6 years and to investigate the correlation between the level of hMPV IgG antibody and neutralizing activity in the same serum.
Sera of 0 to 3 years old children were collected from patients hospitalized for surgery without documented respiratory illnesses, and sera of 3 to 6 years old children were remainder of serum specimens taken for health checkup. Total number of serum specimens was 325. Ten serum samples were selected for neutralizing activity detection in every age group and the sum was 50. The neutralizing titer was assessed by microneutralization assay which had been well documented previously.
Among 50 serum samples, eight in which hMPV IgG antibody was proved negative by ELISA previously did not show any neutralizing activity. The remaining 42 samples, as expected, showed variable neutralizing activity. The geometric mean neutralizing titer to hMPV for all the samples was 1:129. In the age group of 0-5 months, the geometric mean titer was 1:160. In the age groups of 6-11 months, 12-23 months, 24-35 months, 3-6 years, the geometric mean titers were 1:58.9, 1:114.9, 1:172.8 and 1:160.0, respectively. The level of hMPV antibody and neutralizing activity in the same serum was significantly correlated (r = 0.668).
Most 0-6 year-old children in Chongqing area have neutralizing antibody in their serum. Whether such neutralizing activity is high enough to prevent infection with different subtypes of hMPV is unknown.
人偏肺病毒（hMPV）已被确认为儿童急性呼吸道感染最重要的病毒病原体之一。本研究旨在观察0至6岁无呼吸道疾病儿童血清中对hMPV的中和活性，并探讨同一血清中hMPV IgG抗体水平与中和活性之间的相关性。
0至3岁儿童的血清采集自因手术住院且无呼吸道疾病记录的患者，3至6岁儿童的血清采集自健康体检剩余的血清标本。血清标本总数为325份。每个年龄组选取10份血清样本进行中和活性检测，共50份。中和滴度通过先前已充分记录的微量中和试验进行评估。
在50份血清样本中，先前经ELISA证明hMPV IgG抗体为阴性的8份样本未显示任何中和活性。其余42份样本，如预期的那样，显示出不同的中和活性。所有样本对hMPV的几何平均中和滴度为1:129。在0至5个月年龄组中，几何平均滴度为1:160。在6至11个月、12至23个月、24至35个月、3至6岁年龄组中，几何平均滴度分别为1:58.9、1:114.9、1:172.8和1:160.0。同一血清中hMPV抗体水平与中和活性显著相关（r = 0.668）。
重庆地区大多数0至6岁儿童血清中有中和抗体。这种中和活性是否足以预防不同亚型hMPV的感染尚不清楚。
