A promising endeavor against human cytomegalovirus: Predominant epitopes-based recombinant subunit vaccine RH <i>Ec</i> ^{IE1/pp65/pp150}

Human cytomegalovirus (HCMV) is widespread in the population, typically remaining latent. However, it can cause severe morbidity and mortality in transplant patients and immunodeficient individuals. Currently, there is no approved vaccine against HCMV. This study used immunoinformatics methods to predict the predominant T and B-cell epitopes of three key HCMV proteins, including phosphoprotein 65 (pp65), pp150, and immediate-early protein 1 (IE1). Subsequently, we synthesized a recombinant subunit vaccine (RH<i>Ec</i>^{IE1/pp65/pp150}) from <i>Escherichia coli</i>, comprising RH<i>Ec</i>-1 and RH<i>Ec</i>-2. We observed that the RH<i>Ec</i>^{IE1/pp65/pp150} vaccine exhibited high safety and immunogenicity in mice, enhancing a significant upregulation of CD80, CD86, CD40, and MHCII on dendritic cells and macrophages. Additionally, the vaccine activated innate immune responses through the NF-κB signalling pathway, triggering CD4⁺ and CD8⁺T cells to secrete tumour necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-2, directing the T-cell response towards Th1. Moreover, it stimulated CD4⁺T cells to secrete IL-4, IL-6, and IL-10, promoting B-cell immunity. Furthermore, the RH<i>Ec</i>^{IE1/pp65/pp150} vaccine induced the formation of abundant memory cells and high levels of neutralizing antibody titres, conducive to providing long-lasting protection. Taken together, the RH<i>Ec</i>^{IE1/pp65/pp150} vaccine is a promising endeavour against HCMV, and these findings contribute valuable insights to the development of HCMV vaccine candidates.