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目的观察从死禽体内分离的禽流感H5N1病毒株对小鼠的致病情况,筛选一株可用于小鼠攻毒实验的H5N1毒株。方法将17株禽源H5N1病毒分别滴鼻感染6～8周龄Balb/c小鼠,观察其对小鼠的致病和致死情况。通过测定其中毒力较强一株的EID_(50)、TCID_(50)、小鼠LD_(50)及濒死小鼠不同组织中病毒载量,判定其致病力;采用遗传进化分析绘制HA基因进化树,了解其进化特征。结果动物实验表明,17株高致病性禽源H5N1毒株中,仅有一株对小鼠为高致病性。该毒株TCID_(50)/100μl=7.2,EID_(50)/100μl=8.325,小鼠1 LD_(50)/100μl=6.318≈10~2EID_(50)。鼻粘膜感染4～6 d小鼠发病,表现为精神萎靡、食欲减退、竖毛、弓背等临床症状,体重明显减轻。小鼠死亡集中在发病后的2～5 d,耐过死亡者12 d完全恢复正常。从濒死感染小鼠脾、肺、鼻及脑组织中皆可检出流感病毒NS片段,病毒数载量以脑组织中最多,达3.56×10~(10)拷贝/5μl。结论筛选到一株对小鼠呈强致病性H5N1亚型禽流感毒株,可以用于禽流感疫苗交叉保护效果评价的小鼠攻击实验,也可以作为感染模型用于H5N1禽流感病毒致病机制的研究。
Objective To observe the pathogenicity of H5N1 strain of bird flu isolated from dead fowls in mice and screen a H5N1 strain which can be used in mice challenge experiment. Methods Seventeen H5N1 avian H5N1 viruses were intranasally infected with Balb / c mice aged 6 to 8 weeks to observe their pathogenicity and lethality in mice. The pathogenicity of the virus was determined by measuring the viral load of EID 50, TCID 50, LD 50 and the moribund mice of one of the most virulent strains. The genetic evolution analysis was used to draw the HA Phylogenetic tree to understand its evolutionary characteristics. Results Animal experiments showed that only one of the 17 highly pathogenic avian H5N1 strains was highly pathogenic to mice. The strain TCID 50/100 μl = 7.2, EID 50/100 μl = 8.325, mouse 1 LD 50/100 μl = 6.318 10 ~ 2EID 50. Nasal mucosal infection 4 ~ 6 d mice onset, manifested as apathetic, loss of appetite, vertical hair, bow and other clinical symptoms, weight was significantly reduced. The death of mice concentrated in the 2 to 5 days after onset, 12 days after the death of those who died completely returned to normal. The NS fragment of influenza virus could be detected in the spleen, lung, nose and brain tissue of the moribund mice. The viral load was up to 3.56 × 10 ~ (10) copies / 5μl in brain tissue. Conclusion A strain of H5N1 avian influenza virus that is strongly pathogenic to mice was screened and could be used in mouse challenge experiment to evaluate the cross protection effect of bird flu vaccine. It can also be used as an infection model for H5N1 avian influenza virus pathogenicity Mechanism of research.