Dong Zhaopeng, Zhang Zhenjie, Yang Leiying, Li Dong, Shi Weifeng
Bing Du Xue Bao. 2016 Nov;32(6):671-82.
We aimed to study infections in neonatal ICR mice of different ages infected with Enterovirus 71(EV-A71)through three routes of infection, and to explore the dynamic distribution and infection mechanism of EV-A71 in vivo.Three-,5-and 9-day-old neonatal ICR mice were infected with an EV-A71 strain isolated from a child with severe hand, foot and mouth disease through intramuscular(IM), intraperitoneal (IP)and intracerebral (IC)injection, respectively. Consequently, blood, brain, hind-limb muscle, heart, and intestines of mice were collected at regular intervals. Changes in viral load in organs were measured using real-time polymerase chain reaction. Hematoxylin and eosin staining and immunohistochemical (IHC)analyses were undertaken to detect pathogenic and pathologic changes in infected mice.Five-day-old neonatal mice infected with EV-A71 through IM,IP or IC routes had obvious neurologic symptoms and a high mortality rate. Symptoms were alleviated slightly with increasing age of mice upon injection. However, the pathogenicity associated with IM and IP injections was more severe than that of IC injection. Also, the mortality rates of IM and IP injections were significantly higher than that of IC injection. Compared with the control group, the mean body weight(in g)of 3-day-old neonatal mice at 6days post-infection(dpi)injected by IM,IP and IC routes decreased by 1.54(31.43%),1.31(15.06%)and 2.52(44.28%),respectively. Similarly, the mean body weight(in g)of 5-day-old neonatal mice at 6dpi injected by IM and IP decreased by 0.605(8.95%),0.886(15.51%),whereas that of mice injected by IC increased by 0.904(14.70%).The body weight of all infection groups was significantly lower than that of the control group(P<0.05).All 3-day-old neonatal mice infected with EV-A71 through IM,IP and IC routes died at 9dpi.Survival rates of 5-day-old neonatal mice infected through IM,IP and IC routes at 9dpi and14 dpi were 42.8%,25%,and 87.5%,and 0%,0%,and 25%,respectively.Those of 9-day-old neonatal mice at 14 dpi were 70%,69.23% and 100%,respectively.Pathologic and IHC examination showed that EV-A71 had a strong preference for infecting nervous systems and skeletal muscle, and could also lead to: viremia; necrosis of brain neurons and skeletal muscle; myocardial interstitial edema; inflammatory response of multiple organs. These data suggest that 5-day-old ICR neonatal mice injected through IM or IP routes can establish an ideal model of infection by EV-A71 in mice.
我们旨在研究不同年龄的新生ICR小鼠经三种感染途径感染肠道病毒71型（EV - A71）后的感染情况，并探讨EV - A71在体内的动态分布及感染机制。分别通过肌肉注射（IM）、腹腔注射（IP）和脑内注射（IC），将从一名重症手足口病患儿分离出的EV - A71毒株感染3日龄、5日龄和9日龄的新生ICR小鼠。随后，定期采集小鼠的血液、脑、后肢肌肉、心脏和肠道。采用实时聚合酶链反应检测各器官中病毒载量的变化。进行苏木精 - 伊红染色和免疫组织化学（IHC）分析，以检测感染小鼠的致病和病理变化。经IM、IP或IC途径感染EV - A71的5日龄新生小鼠出现明显的神经症状且死亡率高。注射时随着小鼠年龄增长症状略有缓解。然而，IM和IP注射相关的致病性比IC注射更严重。此外，IM和IP注射的死亡率显著高于IC注射。与对照组相比，经IM、IP和IC途径注射的3日龄新生小鼠在感染后6天（dpi）的平均体重（g）分别下降了1.54（31.43%）、1.31（15.06%）和2.52（44.28%）。同样，经IM和IP注射的5日龄新生小鼠在6 dpi时的平均体重（g）分别下降了0.605（8.95%）、0.886（15.51%），而经IC注射的小鼠体重增加了0.904（14.70%）。所有感染组的体重均显著低于对照组（P<0.05）。经IM,IP和IC途径感染EV - A71的所有3日龄新生小鼠在9 dpi时死亡。经IM、IP和IC途径感染的5日龄新生小鼠在9 dpi和14 dpi时的存活率分别为42.8%、25%和87.5%，以及0%、0%和25%。9日龄新生小鼠在14 dpi时的存活率分别为70%、69.23%和100%。病理和IHC检查表明，EV - A71对感染神经系统和骨骼肌有很强的偏好，还可导致：病毒血症；脑神经元和骨骼肌坏死；心肌间质水肿；多器官炎症反应。这些数据表明，经IM或IP途径注射的5日龄ICR新生小鼠可建立理想的小鼠EV - A71感染模型。
