Name: interferons block viral replication
Uploaded: 2026-03-12T13:36:03.000Z
Duration: 1 min 30 s
Channel: JoVE

インターフェロンはウイルスのタンパク質合成を阻害することでウイルスの複製を抑制する自然な抗ウイルス薬です。ペギル化インターフェロンは、ポリエチレングリコールをインターフェロンに結合させることで作られる組換えインターフェロンの一種です。これらのインターフェロンは健康な宿主細胞の受容体に結合し、インターフェロン刺激遺伝子の発現を引き起こします。これらの遺伝子は、当初は不活性状態で存在する複数の抗ウイルスタンパク質の合成を誘導します。そのうち3つ、タンパク質キナーゼR、オリゴアデニル酸合成酵素、RNaseLはウイルスmRNAの翻訳を妨害する重要な役割を果たします。ウイルス感染時には、ウイルスの二本鎖RNAの存在がこれらのタンパク質を活性化します。アクティブプロテインキナーゼRは真核生物の翻訳開始因子2⍺をリン酸化し、ウイルスおよび宿主mRNAの翻訳を妨げます。さらに、オリゴアデニル酸合成酵素はRNase Lを活性化するアデニル酸分子の短い鎖を合成します。活性RNase Lはウイルスおよび宿主mRNAを分解し、感染細胞内のタンパク質合成を停止させます。これにより細胞死を促進し、ウイルスの複製を制限します。

ウイルスタンパク質合成阻害剤

Inhibitors of Viral Protein Synthesis

ウイルスの複製にはタンパク質合成が不可欠です。ウイルスはこの過程に必要な細胞機構を持たず、宿主の翻訳装置を乗っ取らなければなりません。これに対抗して、宿主細胞はインターフェロンという特殊なサイトカインを用いて、ウイルスの伝播を抑制する重要な先天免疫防御を展開します。ウイルス検出後、感染細胞はインターフェロンを放出し、隣接する未感染細胞の受容体に結合してJAK-STATシグナル伝達経路を活性化し、インターフェロン刺激遺伝子(ISG)の発現を促します。これらのISGは、タンパク質キナーゼR(PKR)、2',5'-オリゴアデニル酸合成酵素(OAS)、およびRNase Lの3つの主要な抗ウイルスタンパク質の発現を誘導します。感染に関連する分子パターンであるウイルス二本鎖RNA(dsRNA)は、PKRおよびOASを直接活性化します。活性化されたPKRは真核生物翻訳開始因子2(eIF2α)のαサブユニットをリン酸化し、mRNA翻訳の開始を停止し、ウイルスおよび宿主タンパク質合成の両方を抑制します。同時に、OASはRNase Lを活性化する2',5'結合オリゴアデニル酸の産生を触媒します。活性RNase Lはウイルスおよび細胞のRNA(リボソームRNAを含む)を切断し、タンパク質合成の停止を悪化させ、細胞内の抗ウイルス状態を増幅させます。組換えインターフェロンの臨床応用その強力な抗ウイルス特性から、組換えインターフェロンは複数のウイルス疾患の臨床管理に利用されています。<ul><li>抗ウイルス療法:インターフェロンα(IFN-α)は、慢性B型およびC型肝炎感染症の治療において歴史的な基盤となっており、ウイルス量を減らし、疾患の進行を遅らせています。C型肝炎では、直接作用型抗ウイルス薬(DAA)が登場する以前は、ペギル化インターフェロンとリバビリンの併用が標準治療法でしたが、現在ではDAAの方が優れた有効性と耐容性を示しています。IFN-αはまた、ヒトパピローマウイルス(HPV)関連病変やHIVに関連するカポジ肉腫の治療にも用いられます。</li><li>腫瘍学:IFN-αは、有毛細胞白血病や慢性骨髄性白血病、悪性メラノーマ、腎細胞癌など、特定の血液悪性腫瘍において免疫調節剤として作用します。</li><li>免疫学:インターフェロンベータ(IFN-β)は多発性硬化症の管理に広く用いられ、再発頻度を減らし障害の進行を遅らせます。</li></ul>臨床的利益にもかかわらず、インターフェロン療法はインフルエンザ様症状、疲労、うつ病、血液学的異常などの副作用を伴い、一部の患者で使用が制限されることがあります。それでも、これらの多様な応用は、抗ウイルス薬、腫瘍学的、免疫学的領域におけるインターフェロンの多様性と臨床的重要性を強調しています。

Protein synthesis is indispensable for viral replication, as viruses lack the cellular machinery required for this process and must hijack the host's ...

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主要な用語と概念

interferons block viral replication

Interferons block viral replication by shutting down protein synthesis and activating the cell’s antiviral defenses. Viruses need the host cell’s translational machinery to make proteins, because they do not have the machinery to do this on their own. When a virus is detected, infected cells release interferons, which are cytokines, or signaling proteins, that warn nearby uninfected cells.

Interferons bind to receptors on nearby cells and activate the JAK-STAT signaling pathway. This turns on interferon-stimulated genes, or ISGs. These genes lead to the production of three key antiviral proteins: protein kinase R (PKR), 2',5'-oligoadenylate synthetase (OAS), and RNase L.

Viral double-stranded RNA, or dsRNA, helps activate PKR and OAS. PKR phosphorylates the alpha subunit of eukaryotic translation initiation factor 2, called eIF2alpha. This blocks the start of mRNA translation and slows both viral and host protein synthesis. At the same time, OAS makes 2',5'-linked oligoadenylates, which activate RNase L.

Active RNase L breaks down viral and cellular RNA, including ribosomal RNA. This deepens the shutdown of protein synthesis and strengthens the antiviral state in the cell. Recombinant interferons have also been used in medicine, especially for chronic hepatitis B and C, HPV-associated lesions, and Kaposi's sarcoma linked to HIV.

Interferon-alpha, or IFN-alpha, was a historical treatment for hepatitis C before direct-acting antivirals became available. Pegylated interferon with ribavirin was once standard therapy for hepatitis C. IFN-alpha is also used in some cancers, including hairy cell leukemia, chronic myeloid leukemia, malignant melanoma, and renal cell carcinoma.

Interferon-beta, or IFN-beta, is used to manage multiple sclerosis. It can reduce relapse frequency and slow disability progression. Interferon treatments can also cause flu-like symptoms, fatigue, depression, and blood-related abnormalities, which may limit their use.

Interferons Block Viral Replication

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key terms and concepts

Learn how interferons stop viral replication by turning on PKR, OAS, and RNase L, and see their uses in hepatitis, HPV, cancer, and multiple sclerosis.

Interferons Block Viral Replication | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Interferons Block Viral Replication

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