Increasing Efficacy of Enveloped Whole-Virus Vaccines by In situ Immune-Complexing with the Natural Anti-Gal Antibody.
Increasing Efficacy of Enveloped Whole-Virus Vaccines by In situ Immune-Complexing with the Natural Anti-Gal Antibody.
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DOI：
10.18103/mra.v9i7.2481
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发表时间：
2021-07-01
期刊：
影响因子：
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通讯作者：
Galili, Uri
中科院分区：
文献类型：
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作者：
Galili, Uri
Covid-19大流行期间出现的突变病毒变体引发了人们对可能形成变体的风险的担忧，这些变体可以逃避基于单抗原S蛋白基因的疫苗引发的保护性免疫反应。这种风险可以通过在疫苗中包含多种抗原来避免，这样，逃避对 SARS-CoV-2 病毒 S 蛋白免疫反应的变体将被针对其他病毒抗原的保护性免疫反应所破坏。制备多抗原包膜病毒疫苗的一种简单方法是使用灭活的全病毒作为疫苗。然而，此类疫苗的免疫原性可能不是最理想的，因为抗原呈递细胞 (APC) 对疫苗的摄取较差，这是由于疫苗病毒的聚糖屏蔽和 APC 的碳水化合物链（聚糖）上唾液酸负电荷的静电排斥所致。此外，聚糖屏蔽可以掩盖许多抗原肽。通过糖工程病毒聚糖，用α-gal表位（Galalpha1-3Galbeta1-4GlcNAc-R）取代聚糖上的唾液酸单位，可以减少聚糖屏蔽的这些影响，并显着增加疫苗接种病毒的免疫原性。用具有 α-gal 表位的灭活全病毒（virusalpha-gal）对人类进行疫苗接种，会导致与疫苗接种部位的病毒 α-gal 表位结合的丰富天然抗 Gal 抗体形成免疫复合物。由于免疫复合物抗 Gal 的 Fc 部分与 APC 上的 Fcgamma 受体结合，这些免疫复合物以 APC 为目标进行严格摄取。 APC 进一步将大量内化的疫苗接种病毒转运至区域淋巴结，处理并呈递病毒抗原肽，以激活病毒特异性辅助 T 细胞和细胞毒性 T 细胞的许多克隆。这引发了针对多种病毒抗原的保护性细胞和体液免疫反应以及有效的免疫记忆。在产生抗 Gal 并用灭活流感病毒α-gal 免疫的小鼠中研究了病毒α-gal 疫苗的免疫反应。与缺乏 α-gal 表位的类似疫苗相比，这些小鼠产生的抗体滴度增加了 100 倍，T 细胞反应显着增加，并且几乎完全抵御致命剂量的活流感病毒的攻击。这种糖工程可以在体外通过以下方式实现：与去除唾液酸的神经氨酸酶和合成α-gal表位的重组α1,3半乳糖基转移酶（α1,3GT）进行酶促反应；通过工程化宿主细胞以包含多个拷贝的α1,3GT基因（GGTA1）；或通过在复制缺陷型腺病毒载体中将该基因转导到宿主细胞中。理论上，这些增强免疫原性的方法可能适用于所有包膜上带有 N-聚糖的有包膜病毒。
The appearance of variants of mutated virus in course of the Covid-19 pandemic raises concerns regarding the risk of possible formation of variants that can evade the protective immune response elicited by the single antigen S-protein gene-based vaccines. This risk may be avoided by inclusion of several antigens in vaccines, so that a variant that evades the immune response to the S-protein of SARS-CoV-2 virus will be destroyed by the protective immune response against other viral antigens. A simple way for preparing multi-antigenic enveloped-virus vaccines is using the inactivated whole-virus as vaccine. However, immunogenicity of such vaccines may be suboptimal because of poor uptake of the vaccine by antigen-presenting-cells (APC) due to electrostatic repulsion by the negative charges of sialic-acid on both the glycan-shield of the vaccinating virus and on the carbohydrate-chains (glycans) of APC. In addition, glycan-shield can mask many antigenic peptides. These effects of the glycan-shield can be reduced and immunogenicity of the vaccinating virus markedly increased by glycoengineering viral glycans for replacing sialic-acid units on glycans with alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R). Vaccination of humans with inactivated whole-virus presenting alpha-gal epitopes (virusalpha-gal) results in formation of immune-complexes with the abundant natural anti-Gal antibody that binds to viral alpha-gal epitopes at the vaccination site. These immune-complexes are targeted to APC for rigorous uptake due to binding of the Fc portion of immunecomplexed anti-Gal to Fcgamma receptors on APC. The APC further transport the large amounts of internalized vaccinating virus to regional lymph nodes, process and present the virus antigenic peptides for the activation of many clones of virus specific helper and cytotoxic T-cells. This elicits a protective cellular and humoral immune response against multiple viral antigens and an effective immunological memory. The immune response to virusalpha-gal vaccine was studied in mice producing anti-Gal and immunized with inactivated influenza-virusalpha-gal. These mice demonstrated 100-fold increase in titer of the antibodies produced, a marked increase in T-cell response, and a near complete protection against challenge with a lethal dose of live influenza-virus, in comparison to a similar vaccine lacking alpha-gal epitopes. This glycoengineering can be achieved in vitro by enzymatic reaction with neuraminidase removing sialic-acid and with recombinant alpha1,3galactosyltransferase (alpha1,3GT) synthesizing alpha-gal epitopes, by engineering host-cells to contain several copies of the alpha1,3GT gene (GGTA1), or by transduction of this gene in a replication-defective adenovirus vector into host-cells. Theoretically, these methods for increased immunogenicity may be applicable to all enveloped viruses with N-glycans on their envelope.