Intracerebral inoculation of mouse-passaged Saffold virus type 3 affects cerebellar development in neonatal mice.
Intracerebral inoculation of mouse-passaged Saffold virus type 3 affects cerebellar development in neonatal mice.
复制标题
小鼠传代的 3 型萨福尔德病毒的脑内接种会影响新生小鼠的小脑发育。
作者：
Kotani O;Suzuki T;Yokoyama M;Iwata-Yoshikawa N;Nakajima N;Sato H;Hasegawa H;Taguchi F;Shimizu H;Nagata N.
萨福德病毒(SAFV)是一种人类心脏病毒，偶尔会在患有脑膜炎和小脑炎等神经系统疾病的婴儿中检测到。我们最近报道，SAFV 3型分离株可以感染小鼠的小脑神经胶质细胞，但不能感染大神经元。然而，这种感染的影响尚不清楚。在这里，我们利用新生BALB/c小鼠小脑传代SAFV，确定了SAFV 3型在新生ddy小鼠小脑中的神经致病作用。接种5株传代毒株后，小脑病毒滴度均升高。第5代株在VP2(H160R和Q239R)和VP3(K62M)衣壳蛋白中存在氨基酸替换。衣壳蛋白的分子模拟表明，VP2-H160R和VP3-K62M突变通过在VP2泡芙B和VP3旋钮区域之间形成一种新的疏水相互作用来改变受体结合表面的结构动力学。与原始菌株相比，传代菌株在人源性星形胶质细胞系中的生长特征发生了变化，并在新生小鼠的大脑中进行了更多的复制。此外，传代菌株的神经毒力比原始菌株更强，而两种菌株都感染了小鼠大脑中的星形胶质细胞和神经前体细胞。无论是原始菌株还是传代菌株，脑内接种均可影响脑浦肯野细胞树突，高滴度传代菌株可诱导新生小鼠小脑发育不良。因此，通过小鼠传代的SAFV感染会影响新生小鼠的小脑发育。该动物模型有助于了解婴幼儿SAFV感染的神经致病机制。传染性非典型肺炎病毒(SAFV)是婴幼儿神经致病的候选病原体，但其神经致病机制尚未完全阐明。最近，我们对两株SAFV临床分离株在小鼠身上的致病性进行了评估。与其他嗜神经性小核糖核酸病毒相似，这些分离株对小脑中的神经胶质和神经前体细胞表现出轻微的感染性，但对大神经元没有感染性。然而，这种病毒感染在小脑中的结果尚不清楚。在这里，我们研究了SAFV在小脑中的取向。我们从新生小鼠的小脑中获得了一株体内传代的菌株，并检测了它的基因组及其在新生小鼠脑中的神经毒力。传代病毒在脑内尤其是小脑表现出高度的感染性和神经毒力，并影响小脑的发育。这种独特的新生小鼠模型将有助于阐明SAFV感染发生在生命早期的神经发病机制。
Saffold virus (SAFV), a human cardiovirus, is occasionally detected in infants with neurological disorders, including meningitis and cerebellitis. We recently reported that SAFV type 3 isolates infect cerebellar glial cells, but not large neurons, in mice. However, the impact of this infection remained unclear. Here, we determined the neuropathogenesis of SAFV type 3 in the cerebella of neonatal ddY mice by using SAFV passaged in the cerebella of neonatal BALB/c mice. The virus titer in the cerebellum increased following the inoculation of each of five passaged strains. The fifth passaged strain harbored amino acid substitutions in the VP2 (H160R and Q239R) and VP3 (K62M) capsid proteins. Molecular modeling of the capsid proteins suggested that the VP2-H160R and VP3-K62M mutations alter the structural dynamics of the receptor binding surface via the formation of a novel hydrophobic interaction between the VP2 puff B and VP3 knob regions. Compared with the original strain, the passaged strain showed altered growth characteristics in human-derived astroglial cell lines and greater replication in the brains of neonatal mice. In addition, the passaged strain was more neurovirulent than the original strain, while both strains infected astroglial and neural progenitor cells in the mouse brain. Intracerebral inoculation of either the original or the passaged strain affected brain Purkinje cell dendrites, and a high titer of the passaged strain induced cerebellar hypoplasia in neonatal mice. Thus, infection by mouse-passaged SAFV affected cerebellar development in neonatal mice. This animal model contributes to the understanding of the neuropathogenicity of SAFV infections in infants.IMPORTANCESaffold virus (SAFV) is a candidate neuropathogenic agent in infants and children, but the neuropathogenicity of the virus has not been fully elucidated. Recently, we evaluated the pathogenicity of two clinical SAFV isolates in mice. Similar to other neurotropic picornaviruses, these isolates showed mild infectivity of glial and neural progenitor cells, but not of large neurons, in the cerebellum. However, the outcome of this viral infection in the cerebellum has not been clarified. Here, we examined the tropism of SAFV in the cerebellum. We obtained anin vivo-passaged strain from the cerebella of neonatal mice and examined its genome and its neurovirulence in the neonatal mouse brain. The passaged virus showed high infectivity and neurovirulence in the brain, especially the cerebellum, and affected cerebellar development. This unique neonatal mouse model will be helpful for elucidating the neuropathogenesis of SAFV infections occurring early in life.