Tri-Institutional Training Program in Laboratory Animal Medicine and Science, Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine, and The Rockefeller University, New York, New York;, Email:
Tri-Institutional Training Program in Laboratory Animal Medicine and Science, Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine, and The Rockefeller University, New York, New York; Center for Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center and Weill Cornell Medicine, New York, New York.
Comp Med. 2021 Dec 1;71(6):474-484. doi: 10.30802/AALAS-CM-21-000039. Epub 2021 Nov 18.
Murine astrovirus 2 (MuAstV2) is a novel murine astrovirus recently identified in laboratory and wild mice. MuAstV2 readily transmits between immunocompetent mice yet fails to transmit to highly immunocompromised mouse strains-a unique characteristic when contrasted with other murine viruses including other astroviruses. We characterized the viral shedding kinetics and tissue tropism of MuAstV2 in immunocompetent C57BL/6NCrl mice and evaluated the apparent resistance of highly immunocompromised NOD- /NjuCrl mice to MuAstV2 after oral inoculation. Temporal patterns of viral shedding were determined by serially measuring fecal viral RNA. Tissue tropism and viral load were characterized and quantified by using in-situ hybridization (ISH) targeting viral RNA. Cellular tropism was characterized by evaluating fluorescent colocalization of viral ISH with various immunohistochemical markers. We found a rapid increase of fecal viral RNA in B6 mice, which peaked at 5 d after inoculation (dpi) followed by cessation of shedding by 168 dpi. The small intestine had the highest percentage of hybridization (3.09% of tissue area) of all tissues in which hybridization occurred at 5 dpi. The thymus displayed the next highest degree of hybridization (2.3%) at 7 dpi, indicating extraintestinal viral spread. MuAstV2 RNA hybridization was found to colocalize with only 3 of the markers evaluated: CD3 (T cells), Iba1 (macrophages), and cytokeratin (enterocytes). A higher percentage of CD3 cells and Iba1 cells hybridized with MuAstV2 as compared with cytokeratin at 2 dpi (CD3, 59%; Iba1, 46%; cytokeratin, 6%) and 35 dpi (CD3, 14%; Iba1, 55%; cytokeratin, 3%). Neither fecal viral RNA nor viral hybridization was noted in NCG mice at the time points examined. In addition, mice of mixed genetic background were inoculated, and only those with a functioning gene shed MuAstV2. Results from this study suggest that infection of, or interaction with, the immune system is required for infection by or replication of MuAstV2.
鼠星状病毒 2（MuAstV2）是一种新型鼠星状病毒，最近在实验室和野生鼠中被发现。MuAstV2 在免疫功能正常的小鼠之间容易传播，但不能传播给高度免疫功能低下的小鼠品系——与其他鼠病毒（包括其他星状病毒）相比，这是一个独特的特征。我们描述了 MuAstV2 在免疫功能正常的 C57BL/6NCrl 小鼠中的病毒脱落动力学和组织嗜性，并评估了高度免疫功能低下的 NOD-/-/NjuCrl 小鼠在口服接种后的抗 MuAstV2 能力。通过连续测量粪便病毒 RNA 来确定病毒脱落的时间模式。通过针对病毒 RNA 的原位杂交（ISH）来描述和定量组织嗜性和病毒载量。通过评估病毒 ISH 与各种免疫组织化学标志物的荧光共定位来描述细胞嗜性。我们发现 B6 小鼠的粪便病毒 RNA 迅速增加，在接种后 5 天达到高峰（dpi），然后在 168dpi 停止脱落。小肠是所有发生杂交的组织中杂交百分比最高的（组织面积的 3.09%）。胸腺在 7dpi 时显示出下一个最高的杂交程度（2.3%），表明肠外病毒传播。MuAstV2 RNA 杂交仅与评估的 3 种标志物中的 1 种共定位：CD3（T 细胞）、Iba1（巨噬细胞）和细胞角蛋白（肠细胞）。与细胞角蛋白相比，在 2dpi（CD3，59%；Iba1，46%；细胞角蛋白，6%）和 35dpi（CD3，14%；Iba1，55%；细胞角蛋白，3%）时，更多的 CD3 细胞和 Iba1 细胞与 MuAstV2 杂交。在检查的时间点，NCG 小鼠中均未检测到粪便病毒 RNA 或病毒杂交。此外，接种了混合遗传背景的小鼠，只有那些具有正常功能的 基因的小鼠才会排出 MuAstV2。本研究结果表明，感染或与免疫系统相互作用是 MuAstV2 感染或复制所必需的。
