APOBEC3/Rfv3 and Immunoglobulin Somatic Hypermutation

APOBEC3/Rfv3 和免疫球蛋白体细胞超突变

• 批准号: 9179597
• 负责人: Mario Luis Santiago
• 金额: $ 49.35万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9179597
• 关键词: Acute; Acute Erythroblastic Leukemia; Adjuvant; Affinity; Agonist; Antibodies; Antibody Affinity; Antibody Response; Antigens; Antiviral Agents; Attenuated; Automobile Driving; B-Lymphocytes; Binding; Biology; Clinical; Communicable Diseases; Complex; DNA; Data; Deaminase; Deamination; Deoxycytidine; Deoxyuridine; Development; Disease; Enzymes; Exhibits; Family; Friend Murine Leukemia Virus; Friends; GTP-Binding Protein alpha Subunits, Gs; Gammaretrovirus; Genes; HIV-1; Human; Immune; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin Genes; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulins; Immunologics; Infection; Influenza; Interferon-alpha; Interferons; Link; Mediating; Modeling; Molecular; Mus; Mutate; Mutation; Pathogenicity; Pathway interactions; Plasma Cells; Process; Proteins; Purines; Pyrimidine; Reaction; Recovery; Reporting; Resistance; Retroviridae; Retroviridae Infections; Role; Signal Transduction; Splenomegaly; Structure; Structure of germinal center of lymph node; Study models; Subunit Vaccines; TLR7 gene; Testing; Therapeutic; Transcript; Transgenic Mice; Vaccination; Vaccine Adjuvant; Vaccines; Viral; Viral Vaccines; Viremia; Virion; Virus; Virus Diseases; Virus-like particle; Work; activation-induced cytidine deaminase; base; design; human morbidity; human mortality; in vivo; innovation; insight; interest; nanoparticle; neutralizing antibody; next generation sequencing; novel; particle; pathogen; preference; public health relevance; repaired; resistance gene; response; vaccine-induced immunity; Acute; Acute Erythroblastic Leukemia; Adjuvant; Affinity; Agonist; Antibodies; Antibody Affinity; Antibody Response; Antigens; Antiviral Agents; Attenuated; Automobile Driving; B-Lymphocytes; Binding; Biology; Clinical; Communicable Diseases; Complex; DNA; Data; Deaminase; Deamination; Deoxycytidine; Deoxyuridine; Development; Disease; Enzymes; Exhibits; Family; Friend Murine Leukemia Virus; Friends; GTP-Binding Protein alpha Subunits, Gs; Gammaretrovirus; Genes; HIV-1; Human; Immune; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin Genes; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulins; Immunologics; Infection; Influenza; Interferon-alpha; Interferons; Link; Mediating; Modeling; Molecular; Mus; Mutate; Mutation; Pathogenicity; Pathway interactions; Plasma Cells; Process; Proteins; Purines; Pyrimidine; Reaction; Recovery; Reporting; Resistance; Retroviridae; Retroviridae Infections; Role; Signal Transduction; Splenomegaly; Structure; Structure of germinal center of lymph node; Study models; Subunit Vaccines; TLR7 gene; Testing; Therapeutic; Transcript; Transgenic Mice; Vaccination; Vaccine Adjuvant; Vaccines; Viral; Viral Vaccines; Viremia; Virion; Virus; Virus Diseases; Virus-like particle; Work; activation-induced cytidine deaminase; base; design; human morbidity; human mortality; in vivo; innovation; insight; interest; nanoparticle; neutralizing antibody; next generation sequencing; novel; particle; pathogen; preference; public health relevance; repaired; resistance gene; response; vaccine-induced immunity

 DESCRIPTION (provided by applicant): Neutralizing antibodies (NAb) are important in vaccine protection and recovery from viral infection. Thus, understanding the mechanisms governing NAb development could have significant clinical and translational implications. NAbs develop through a process known as affinity maturation in structures known as Germinal Centers (GCs). In GCs, B cells with rearranged immunoglobulin (Ig) genes undergo somatic hypermutation (SHM), leading to enhanced antibody binding to cognate antigens. Ig SHM is primarily mediated by Activation Induced Deaminase (AID), an enzyme that deaminates deoxycytidines into deoxyuridines in transcribing Ig DNA, resulting in G-to-A or C-to-T transitions. Most antibodies have mutations <10% relative to germline, but antibodies that can broadly neutralize global influenza and HIV-1 strains exhibit unusually high SHM levels (up to 33%). Thus, a better understanding of how Ig SHM occurs during viral infections may inform the design of universal vaccines against antigenically-diverse viral pathogens of global importance. Interestingly, the APOBEC3 enzymes are evolutionarily related to AID. APOBEC3 could counteract retroviruses by deaminating reverse transcripts, leading to lethal G-to-A hypermutation. We reported 6 years ago that APOBEC3 encodes Rfv3, a classical resistance gene in mice that promotes recovery from pathogenic Friend retrovirus infection by stimulating a stronger NAb response1. We recently discovered exciting evidence that APOBEC3 could directly edit virus-specific IgG, but in a different sequence context compared to AID2. Thus, we unraveled APOBEC3- mediated deamination as a novel mechanism for antibody diversification in vivo. This fundamental immunological finding unleashed a plethora of basic questions on APOBEC3-mediated Ig SHM, as this process may be a strategy to augment NAb responses during vaccination. In fact, we reported that APOBEC3 can be regulated by IFNα treatment in vivo3. Moreover, we obtained pilot data showing that a TLR7 agonist may augment vaccine IgG responses via APOBEC3. To expand our understanding of APOBEC3-mediated Ig SHM, we therefore propose to: (Aim 1) evaluate regulatory checkpoints for APOBEC3-mediated Ig SHM during viral infection; (Aim 2) investigate the impact of APOBEC3 in vaccine-induced antibody protection; and (Aim 3) determine if increased NAb potency are due to APOBEC3 mutations. Of note, mice encode only 1 APOBEC3 gene, but humans have seven. Thus, the 7 human APOBEC3 proteins may have a stronger impact on Ig SHM. We will utilize a novel transgenic mouse encoding the entire human APOBEC3 locus to test this hypothesis. We will capitalize on our expertise in the Friend retrovirus infection model, utilize novel murine lines specifically generated for the study, investigate clinically-approved vaccine adjuvants and employ innovative nanoparticle vaccines, single B cell PCR and next-generation sequencing approaches. The proposed studies should provide deeper insights on how APOBEC3 mediates Ig SHM that may inform universal vaccine strategies.

 描述（通过应用程序提供）：中和抗体（NAB）对于疫苗保护和从病毒感染中恢复很重要。这是理解管理NAB发育的机制，可能具有重大的临床和翻译意义。 NABS通过称为生发中心（GCS）的结构中称为亲和力成熟的过程。在GC中，具有重新排列免疫球蛋白（IG）基因的B细胞经历了体细胞超突变（SHM），从而导致抗体与同源抗原的结合增强。 IG SHM主要是由激活诱导的脱肌（AID）介导的，该酶在转录Ig DNA时将脱氧胞苷脱氧丝氨酸脱氧基因定丁碱，从而导致G-TO-A或C-TO-T-T-T-T-T-T-T-TTriontions。相对于种系，大多数抗体的突变<10％，但是可以大致中和全球影响力和HIV-1菌株的抗体表现出异常高的SHM水平（高达33％）。这是对病毒感染过程中IG SHM的发生方式的更好理解，可能会为全球重要性的抗原多样性病毒病原体的普遍疫苗设计。有趣的是，APOBEC3酶在进化上与AID相关。 APOBEC3可以通过脱离逆转录物来抵消逆转录病毒，从而导致致命的g-to-t-t-t-a超成名。我们6年前报道说，APOBEC3编码RFV3，这是小鼠中经典的抗药性基因，可通过刺激更强的NAB反应1来促进病原朋友逆转录病毒感染中的恢复。我们最近发现了令人兴奋的证据，表明APOBEC3可以直接编辑病毒特异性IgG，但与AID2相比，在不同的序列环境中。这，我们将APOBEC3介导的死亡作为体内抗体多样化的新机制。这一基本的免疫学发现除非有关APOBEC3介导的IG SHM的大量基本问题，因为此过程可能是增强疫苗期间NAB反应的策略。实际上，我们报道了apobec3可以通过IFNα处理在VIVO3中调节。此外，我们获得了试验数据，表明TLR7激动剂可以通过APOBEC3增强IgG疫苗反应。因此，为了扩展我们对APOBEC3介导的IG SHM的了解，我们建议：（ AIM 1）评估病毒感染期间APOBEC3介导的IG SHM的调节检查点； （AIM 2）研究APOBEC3在疫苗诱导的抗体保护中的影响； （AIM 3）确定NAB效力增加是否是由于APOBEC3突变引起的。值得注意的是，小鼠仅编码1个apobec3基因，但人类有7个基因。这是7种人Apobec3蛋白可能对IG SHM产生更大的影响。我们将利用一种编码整个人类APOBEC3基因座的新型转基因小鼠来检验该假设。我们将利用我们在朋友逆转录病毒感染模型中的专业知识，利用专门为研究生成的新型鼠系，研究临床批准的疫苗佐剂和员工创新的纳米颗粒疫苗，单个B细胞PCR和下一代测序方法。拟议的研究应提供有关APOBEC3如何介导的IG SHM的更深入的见解，这可能为普遍的疫苗策略提供依据。