The development of an effective HIV-1 vaccine is still a global priority. In recent years, vaccinia virus (VV) has been widely used as an HIV-1 vaccine vector, but its immune efficacy against HIV-1 antigens needs to be optimized. The extracellular enveloped virus (EEV) of VV is capable of faster entry, earlier release, and long-range dissemination. We hypothesized that an improvement in EEV formation by the manipulation of VV genes involved in the EEV release would consequently cause an improved expression of the VV carrying HIV-1 Env antigen and a subsequent enhanced immune response. To this end, an A34R K151E mutant (rVTT-A34R_mut) from VV Tiantan strain (VTT) with robustly increased EEV release was selected to serve as an optimized vaccine vector. The results were consistent with our hypothesis: the A34R mutant-based HIV-1 vaccine candidate rVTT-A34R_mut-Env produced more HIV-1 Env antigen in vitro and in vivo, and thus led to an improved HIV-1 Env-specific T cell immune response, binding antibody, and even the neutralizing antibody response in mice without increased virulence. Meanwhile, the application of the A34R mutation on another VV-based HIV-1 vaccine candidate, VTKgpe, also exhibited a similar immune enhancement effect with no enhanced virulence. The results in this study suggested that rVTT-A34R_mut is a potentially improved vaccine vector candidate for human application. In addition, the improvement of the EEV formation via the A34R gene mutation may also be potent in other poxvirus vector-based vaccines against HIV-1 or other pathogens and even cancer in the future.

开发有效的HIV-1疫苗仍然是全球优先事项。近年来，痘苗病毒（VV）已被广泛用作HIV-1疫苗载体，但是其针对HIV-1抗原的免疫效力需要优化。VV的细胞外被膜病毒（EEV）能够更快进入，更早释放和进行远程传播。我们假设通过操纵参与EEV释放的VV基因来改善EEV的形成将因此导致携带HIV-1 Env抗原的VV表达的改善和随后增强的免疫反应。为此，一个A34R K151E突变体（rVTT-A34R _mut从具有强烈增加的EEV释放的VV天坛菌株（VTT）中选择）作为优化的疫苗载体。结果与我们的假设是一致的：所述突变型A34R基于HIV-1的疫苗候选rVTT-A34R _MUT -Env产生更多的HIV-1包膜抗原在体外和在体内，从而导致改进的HIV-1包膜蛋白特异性T细胞免疫反应，结合抗体，甚至小鼠中和抗体反应，而没有增加毒力。同时，在另一种基于VV的HIV-1疫苗候选药物VTKgpe上应用A34R突变也表现出相似的免疫增强效果，而没有增强的毒力。在这项研究结果表明，rVTT-A34R _MUT是用于人类应用的潜在改良疫苗载体候选物。此外，通过A34R基因突变改善EEV的形成在将来针对HIV-1或其他病原体甚至癌症的其他基于痘病毒载体的疫苗中也可能有效。