Department of Pathology, The Johns Hopkins University, Baltimore, MD 21231, USA.
Virol J. 2009 Oct 27;6:176. doi: 10.1186/1743-422X-6-176.
Vaccination of mice with minor capsid protein L2 or passive transfer with the L2-specific neutralizing monoclonal antibody RG-1 protects against human papillomavirus type 16 (HPV16) challenge. Here we explored the nature of the RG-1 epitope and its contribution to viral infectivity. RG-1 bound equivalently HPV16 L2 residues 17-36 with or without an intact C22-C28 disulphide bridge. HPV16 L2 mutations K20A, C22A, C22S, C28A, C28S, or P29A prevented RG-1 binding, whereas Y19A, K23A or Q24A had no impact. Mutation of either C22 or C28 to alanine or serine compromises HPV16 pseudoviral infectivity both in vitro and in the murine vaginal tract, but does not impact pseudovirion assembly. Despite their lack of infectivity, HPV16 pseudovirions containing C22S or C28S mutant L2 bind to cell surfaces, are taken up, and expose the 17-36 region on the virion surface as for wild type HPV16 pseudovirions suggesting normal furin cleavage of L2. Mutation of the second cysteine residue in Bovine papillomavirus type 1 (BPV1) L2 to serine (C25S) dramatically reduced the infectivity of BPV1 pseudovirions. Surprisingly, in contrast to the double mutation in HPV16 L2, the BPV1 L2 C19S, C25S double mutation reduced BPV1 pseudovirion infectivity of 293TT cells by only half.
用次要衣壳蛋白 L2 对小鼠进行疫苗接种或用 L2 特异性中和单克隆抗体 RG-1 进行被动转移可预防人乳头瘤病毒 16 型（HPV16）的攻击。在这里，我们探讨了 RG-1 表位的性质及其对病毒感染力的贡献。RG-1 与 HPV16 L2 残基 17-36 结合的能力不受是否存在完整的 C22-C28 二硫键的影响。HPV16 L2 的突变 K20A、C22A、C22S、C28A、C28S 或 P29A 阻止了 RG-1 的结合，而 Y19A、K23A 或 Q24A 则没有影响。C22 或 C28 突变为丙氨酸或丝氨酸会损害 HPV16 假病毒在体外和小鼠阴道中的感染性，但不影响假病毒的组装。尽管缺乏感染性，但含有 C22S 或 C28S 突变 L2 的 HPV16 假病毒仍能与细胞表面结合、被摄取，并暴露病毒表面的 17-36 区域，就像野生型 HPV16 假病毒一样，这表明 L2 的furin 切割正常。牛乳头瘤病毒 1 型（BPV1）L2 中的第二个半胱氨酸残基突变为丝氨酸（C25S）会显著降低 BPV1 假病毒的感染性。令人惊讶的是，与 HPV16 L2 的双突变相反，BPV1 L2 C19S、C25S 双突变使 BPV1 假病毒在 293TT 细胞中的感染性降低了一半。
