Substitution of Human Papillomavirus Type 16 L2 Neutralizing Epitopes Into L1 Surface Loops: The Effect on Virus-Like Particle Assembly and Immunogenicity
Substitution of Human Papillomavirus Type 16 L2 Neutralizing Epitopes Into L1 Surface Loops: The Effect on Virus-Like Particle Assembly and Immunogenicity
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DOI：
10.3389/fpls.2019.00779
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发表时间：
2019-06-20
影响因子：
5.6
通讯作者：
Hitzeroth, Inga I.
中科院分区：
文献类型：
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作者：
Chabeda, Mayo;van Zyl, Albertha R.;Hitzeroth, Inga I.
由人乳头瘤病毒（HPV）感染引起的宫颈癌是全球妇女第四大常见癌症，由于医疗资源有限，主要在发展中国家。目前基于免疫显性L1蛋白的重组表达组装的病毒样颗粒（VLP）的疫苗在预防宫颈感染方面非常有效;然而，这些疫苗昂贵且具有类型特异性。因此，需要更广泛的保护和负担得起的疫苗。HPV-16 L2肽序列108-120、65-81、56-81和17-36在几种HPV类型中是高度保守的，并且已经显示出引发交叉中和抗体。为了增加L2免疫原性，开发了L1：L2嵌合VLP（cVLP）疫苗候选物。将上述四种L2肽取代到HPV-16 L1的DE环131位（SAC）或C-末端区域431位（SAE），以产生HPV-16衍生的L1：L2嵌合体。通过根癌农杆菌介导的DNA转移，所有8个嵌合体在本氏烟草中瞬时表达。SAC嵌合体主要组装成高级结构（T = 1和T = 7 VLP），而SAE嵌合体组装成壳粒或形成聚集体。在小鼠的疫苗接种研究中使用了四种SAC和一种SAE嵌合体，并在基于HPV假病毒体的中和测定中分析了它们产生交叉中和抗体的能力。在测试的七种异源HPV中，观察到HPV-11（SAE 65-18）、HPV-18（SAC 108-120、SAC 65-81、SAC 56- 81、SAE 65-81）和HPV-58（SAC 108-120）与嵌合体特异性抗血清的交叉中和。有趣的是，只有抗SAE 65-81抗血清显示出同源HPV-16的中和，表明L2表位展示的位置对于维持L1特异性中和表位至关重要。
Cervical cancer caused by infection with human papillomaviruses (HPVs) is the fourth most common cancer in women globally, with the burden mainly in developing countries due to limited healthcare resources. Current vaccines based on virus-like particles (VLPs) assembled from recombinant expression of the immunodominant L1 protein are highly effective in the prevention of cervical infection; however, these vaccines are expensive and type-specific. Therefore, there is a need for more broadly protective and affordable vaccines. The HPV-16 L2 peptide sequences 108-120, 65-81, 56-81, and 17-36 are highly conserved across several HPV types and have been shown to elicit cross-neutralizing antibodies. To increase L2 immunogenicity, L1:L2 chimeric VLPs (cVLP) vaccine candidates were developed. The four L2 peptides mentioned above were substituted into the DE loop of HPV-16 L1 at position 131 (SAC) or in the C-terminal region at position 431 (SAE) to generate HPV-16-derived L1:L2 chimeras. All eight chimeras were transiently expressed in Nicotiana benthamiana via Agrobacterium tumefaciens-mediated DNA transfer. SAC chimeras predominantly assembled into higher order structures (T = 1 and T = 7 VLPs), whereas SAE chimeras assembled into capsomeres or formed aggregates. Four SAC and one SAE chimeras were used in vaccination studies in mice, and their ability to generate cross-neutralizing antibodies was analyzed in HPV pseudovirion-based neutralization assays. Of the seven heterologous HPVs tested, cross-neutralization with antisera specific to chimeras was observed for HPV-11 (SAE 65-18), HPV-18 (SAC 108-120, SAC 65-81, SAC 56-81, SAE 65-81), and HPV-58 (SAC 108-120). Interestingly, only anti-SAE 65-81 antiserum showed neutralization of homologous HPV-16, suggesting that the position of the L2 epitope display is critical for maintaining L1-specific neutralizing epitopes.