BioVector® 小鼠诺如病毒

BioVector® Murine Norovirus (MNV)

第一部分：中文说明

一、 产品基本信息与病原学背景

• 病原体名称：小鼠诺如病毒（Murine Norovirus, MNV）

• 分类学地位：杯状病毒科（Caliciviridae）、诺如病毒属（Norovirus）、小鼠诺如病毒1型（Murine norovirus 1, MNV-1 及其亚型变异株）

• 物种来源与宿主：主要感染实验室小鼠（Mus musculus），是全球小鼠设施中最常见的传染性病原体之一。

• 基因组结构特征：

  • 属于单股正链无包膜 RNA 病毒（(+)ssRNA），基因组全长约为 7.4 kb。

  • 基因组包含 4 个开放阅读框（ORF1–ORF4），其中 ORF1 编码非结构蛋白多聚前体；ORF2 编码主要衣壳蛋白 VP1；ORF3 编码次要衣壳蛋白 VP2；ORF4 编码调控宿主免疫应答的毒力因子（VF1）。

• 天然受体与细胞嗜性：与人类诺如病毒（HuNV）不同，小鼠诺如病毒能够实现高效的体外细胞培养。它主要靶向感染免疫细胞（如巨噬细胞和树突状细胞），其功能性细胞表面受体已被证实为CD300lf（部分毒株可利用 CD300ld）。

• 生物安全级别：1级（BSL-1）。虽然该病毒对小鼠具有高度传染性，但它不感染人类或其他非啮齿类动物，属于非人畜共欢病原体，可在标准一级生物安全屏障下操作。但为防止实验动物设施交叉污染，建议采取严格的生物防范措施。

二、 病毒形态学与体外传代培养系统

• 病毒颗粒形态：透射电镜下呈现经典的二十面体对称结构，无包膜，直径约为 28–35 nm。

• 推荐宿主细胞（体外扩增）：

  • RAW 264.7（小鼠单核巨噬细胞白血病细胞，首选）

  • M12（小鼠B淋巴细胞株）

• 标准体外增殖培养基配方（以 RAW 264.7 为例）：

  • 基础培养基：高糖 DMEM 培养基。

  • 常规添加：10% 优质胎牛血清（FBS）+ 10 mM HEPES缓冲液 + 1% 非必需氨基酸（NEAA）+ 1% 双抗（青霉素-链霉素）。

• 物理培养参数：37°C 恒温、5% 二氧化碳（$CO_2$）、饱和空气湿度。

三、 病毒扩增、收获与滴定标准操作步骤

1. 常规病毒扩增接种：

   • 待 RAW 264.7 细胞生长汇合至 70%–80% 时，吸除旧培养基，用无菌 PBS 轻轻洗涤。

   • 按感染复数（MOI）为 0.01 至 0.1 的比例加入小鼠诺如病毒液，在 37°C 培养箱中孵育 1 小时以利于病毒吸附（期间可轻轻晃动以确保覆盖均匀）。

   • 吸除病毒接种液，补充含有 2%–5% 低血清浓度的 DMEM 完全培养基。

   • 连续观察 24–48 小时，直至 90% 以上的细胞出现明显的细胞病变效应（CPE），表现为细胞变圆、固缩、折光度改变及大面积脱落。

2. 病毒液收获与纯化：

   • 将带有裂解细胞细胞块的培养液收集至离心管中，置于 -80°C 与 37°C 水浴中进行 3次反复冻融，使胞内复制的病毒颗粒完全释放。

   • 在 4°C 下以 3000 ×g 离心 15 分钟，沉淀细胞碎片。

   • 收集上清液，按需分装后直接存放于 -80°C 超低温冰箱中长期保存（避免反复冻融）。

3. 病毒滴度测定（TCID50 法）：

   • 将 RAW 264.7 细胞以 1×$10^4\text{ cells/well}$ 的密度接种于 96 孔板中，培养过夜。

   • 将收获的病毒液进行 10 倍系列稀释（$10^{-1}$ 至 $10^{-8}$）。

   • 将每个稀释度分别接种 8 个平行孔，每孔加入 100 μL 稀释病毒液。

   • 孵育 3–5 天后显微镜下计数出现 CPE 的孔数，采用 Reed-Muench 法计算 $TCID_{50}/mL$。

四、 核心科研应用方向

1. 人类诺如病毒（HuNV）的替代研究模型：由于人类诺如病毒体外长期连续连续传代极度困难，MNV 作为目前唯一能在常规细胞系中高效高滴度扩增的诺如病毒属成员，被作为国际标准的非包裹RNA病毒模型，广泛用于研究其衣壳结构、吸附机制及抗病毒药物筛选。

2. 消杀制剂与理化物理清除效果评价：广泛作为第三方检测和研发的指示病毒，用于评估医用消毒剂、手部卫生消杀产品、食品加工巴氏灭菌及表面紫外线/放射线对诺如病毒的灭活效率。

3. 粘膜免疫与宿主-病原体相互作用：利用野生型小鼠及特定免疫缺陷小鼠（如 STAT1-/- 或 IFNα/β/γR-/- 小鼠），研究肠道杯状病毒诱导的先天性免疫应答、肠道菌群对病毒感染的调节作用以及持续性感染的分子病理。

PART 2: ENGLISH SECTION

I. General Information and Virological Background

• Pathogen Name: Murine Norovirus (MNV)

• Taxonomic Lineage: Caliciviridae; Norovirus; Murine norovirus 1 (including MNV-1 variants and related persistent field strains)

• Host & Natural Tropism: Naturally infects laboratory mice (Mus musculus), representing one of the most prevalent and highly contagious infectious agents within global animal research facilities.

• Genome Architecture:

  • Encapsidated as a non-enveloped, positive-sense single-stranded RNA ((+)ssRNA) genome spanning approximately 7.4 kb.

  • Organized into 4 distinct Open Reading Frames (ORF1–ORF4): ORF1 encodes a large non-structural polyprotein precursor; ORF2 directs the synthesis of the major capsid protein VP1; ORF3 encodes the minor structural protein VP2; and ORF4 yields a novel virulence factor (VF1) that modulates host immune responses.

• Receptor Usage & Cell Tropism: Unlike human noroviruses (HuNV), MNV replication can be robustly modeled in vitro. It targets professional immune cells, specifically macrophages and dendritic cells, exploiting CD300lf (and occasionally CD300ld) as its primary functional cell surface receptor.

• Biosafety Level: BSL-1. The virus is non-pathogenic to humans or non-rodent species (non-zoonotic). However, due to its rapid spread and persistence in laboratory animal environments, strict biocontainment measures must be integrated during handling to avoid cross-contaminating mouse colonies.

II. Morphological Attributes and Cultivation Systems

• Morphology: Transmission electron microscopy reveals classic small, round, non-enveloped icosahedral capsids exhibiting clear surface depressions, measuring roughly 28–35 nm in diameter.

• Permissive Host Cell Lines (In Vitro Propagation):

  • RAW 264.7 (Mouse monocyte/macrophage leukemia line, highly recommended)

  • M12 (Mouse B lymphoma cell line)

• Standard Growth Medium Formulation (For RAW 264.7 Inoculation):

  • Basal Medium: High-glucose DMEM broth.

  • Routine Maintenance Supplements: 10% premium Fetal Bovine Serum (FBS) + 10 mM HEPES buffer + 1% Non-Essential Amino Acids (NEAA) + 1% Penicillin-Streptomycin.

• Physical Incubation Thresholds: Regulated at 37°C under an atmospheric layer of 5% Carbon Dioxide ($CO_2$) with saturated humidity.

III. Propagation, Harvesting, and Titration Protocols

1. Viral Inoculation Schedule:

   • Seed RAW 264.7 cells and allow them to reach 70%–80% confluence. Aspirate the spent growth medium and wash the monolayer gently with sterile PBS.

   • Inoculate the target monolayer at a Multiplicity of Infection (MOI) of 0.01 to 0.1. Incubate the vessels at 37°C for 1 hour to allow efficient viral attachment, gently tilting the plates occasionally to secure full coverage.

   • Remove the inoculum and replenish with complete DMEM containing a reduced serum percentage (2%–5% low-serum setup).

   • Monitor daily for 24–48 hours until more than 90% of the cells present extensive Cytopathic Effects (CPE), characterized by cell rounding, shrinking, altered refractivity, and widespread detachment.

2. Harvesting & Clarification Processing:

   • Harvest the spent culture containing lysed cellular elements into sterile tubes. Subject the entire volume to 3 consecutive freeze-thaw cycles (alternating between -80°C and 37°C) to break open intact cells and release encapsulated progeny virions.

   • Clarify the crude suspension by centrifuging at 3000 ×g for 15 minutes at 4°C to pellet dense host cell fragments.

   • Collect the clarified supernatant containing the viral particles, aliquot meticulously into working vials, and store at -80°C for long-term survival (avoid repeated freeze-thaw cycles).

3. Viral Quantification via TCID50 Assays:

   • Plate RAW 264.7 cells into 96-well culture plates at a density of 1×$10^4\text{ cells/well}$ and allow them to settle overnight.

   • Perform a log-scale 10-fold serial dilution of the harvested viral master batch ($10^{-1}$ to $10^{-8}$).

   • Add 100 μL of each respective dilution across 8 replicate wells.

   • Incubate for 3–5 days, score the wells for clear manifestations of CPE, and calculate the final infectious titer ($TCID_{50}/mL$) using the standard Reed-Muench formula.

IV. Strategic Research Applications

1. Surrogate Model System for Human Norovirus (HuNV): Because human noroviruses remain notoriously difficult to cultivate in continuous cell lines, MNV serves as the premier surrogate member of the Norovirus genus. It is utilized globally to study calicivirus assembly dynamics, structural biology of viral entry, and for high-throughput screening of entry-blocking small molecules.

2. Disinfectant Efficacy and Biocide Validation Controls: Frequently deployed as a reference testing target for verifying commercial sanitization systems, evaluating hand hygiene formulations, assessing industrial pasteurization, and validating the clearance metrics of UV or gamma radiation on non-enveloped RNA viruses.

3. Mucosal Immunology & Viral Pathogenesis: Utilized in wild-type or specialized gene-knockout mouse lines (such as STAT1-/- or IFNα/β/γR-/- variants) to map mucosal innate immune signaling pathways, dissect the mechanisms behind viral persistence, and decode how the intestinal microbiome regulates or blocks viral colonization tracks.

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