The African Swine Fever Virus (ASFV) poses a major threat to global livestock production by infecting both domestic and wild pigs, causing significant economic loss. Despite promising protective results observed with live attenuated viruses, the safety concern blocked its extensive application. In this study, we developed a novel vaccine combining two recombinant vaccinia viruses-rTTV-D-A and rTTV-K-J-that together express eight ASFV genes, including EP402R (CD2v), B646L (p72), B602L (pB602L), D117L (p17), H240R (pH240R), B438L (p49), E183L (p54), CP204L (p30), and a synthetic T antigen composed of conserved T cell epitopes from multiple ASFV proteins, aiming to induce both humoral and T-cell immune responses against different viral antigens. After demonstrating that this vaccine induced antigen-specific humoral and cellular responses in both mice and swine, its protective efficacy in swine was examined using a lethal challenge model. The vaccinated pigs showed a promising protection against the lethal challenge of a virulent genotype II ASFV strain (100 HAD50/pig), with 4 out of 6 surviving, while all control animals succumbed from 9 to 15 days post challenge. Importantly, the protection was further evidenced by the recovery to normal temperature and no ASFV infection-related clinical signs or virus shedding in surviving pigs over a 21-day observation period. Our results support the potential of rTTV-D-A and rTTV-K-J as a novel multi-immunogen vaccinia-vectored ASFV vaccine. Further studies are warranted to explore and improve its use as a standalone vaccine or in combination with other vaccine platforms to achieve broad and effective protection against ASFV.

Background:Rabies is a lethal zoonotic disease that kills approximately 60,000 people each year. Although inactivated rabies vaccines are available, multiple-dose regimensare recommended for pre-exposure prophylaxis or post-exposure prophylaxis,which cuts down the cost- and time-effectiveness, especially in low- and middle incomecountries.Methods:We developed a nucleoside-modified Rabies mRNA-lipid nanoparticle vaccine (RABV-G mRNA-LNP) encoding codon-optimized viral glycoprotein and assessed the immunogenicity and protective efficacy of this vaccine in mice comparing to a commercially available inactivated vaccine.Results:We first showed that, when evaluated in mice, a single vaccination of RABV-G mRNA with a moderate or high dose induces more potent humoral and T-cell immune responses than that elicited by three inoculations of the inactivated vaccine. Importantly, mice receiving a single immunization of RABV-G mRNA, even at low doses, showed full protection against the lethal rabies challenge. We further demonstrated that the humoral immune response induced by single RABV-G mRNA vaccination in mice could last for at least 25 weeks, while a two-dose strategy could extend the duration of the highly protective response to one year or even longer. In contrast, the three-dose regimen of inactivated vaccine failed to do so.Conclusion:Our study confirmed that it is worth developing a single-dose nucleoside-modified Rabies mRNA-LNP vaccine, which could confer much prolonged and more effective protection.

Objective:To reduce the immunogenicity of vaccinia virus vector by replacing the D8L region, which is a neutralizing antibody epitope in vaccinia virus, with an exogenous gene.Methods:A gene fragment encoding influenza virus hemagglutinin (HA) was inserted into the D8L region to replace it using homologous recombination technique. Then, a recombinant vaccinia virus influenza vaccine was constricted. A recombinant vaccinia virus vaccine with the TK region expressing HA was used as a control. The expression of HA was validated by Western blot. BALB/c mice were immunized with the vaccines and the serum antibody titers two weeks after each immunization were evaluated by ELISA and hemagglutination inhibition assay. The protective efficacy of the recombinant vaccinia virus was assessed through a challenge experiment.Results:Western blot confirmed the successful expression of HAD8L protein in the constructed recombinant vaccines. ELISA and hemagglutination inhibition assay showed that after the primary immunization, the anti-HA antibody titer induced by the recombinant vaccinia virus with D8L region mutation was slightly higher than that induced by the vaccine with TK region mutation, and the difference was statistically significant with the increase of immunization times ( P<0.05). The recombinant vaccinia virus with D8L region mutation showed significantly lower immunogenicity than the recombinant virus with TK region mutation after the primary immunization, but there was no significant difference between them with the increase of immunization times ( P>0.05). After H1N1pdm challenge, no virus was detected in the mice immunized with the recombinant vaccinia virus with D8L region mutation and the mice showed mild lung inflammation and less tissue damage. Conclusions:This study indicated that inserting exogenous genes into the D8L region of the neutralizing antibody epitope in the vaccinia virus vector could help to reduce the immunogenicity of the vector itself and enhance the immunogenicity of the exogenous genes. This provided a reference for the use of the vaccinia virus vector as a delivery tool in the field of vaccines or gene therapy.

Vaccinia virus was used to prevent smallpox. After the World Health Organization declared smallpox extinct, vaccinia virus has been explored for the development of vaccines against a variety of infectious diseases. It also finds a new place in oncolytic therapy. Here we provide a brief review of the history, current status, and future prospect of vaccinia virus-based vaccine and oncolytic virus. New advancements, including a single vaccine targeting multiple viruses, strategies of arming vaccinia viruses to enhance anti-tumor activity, the promise and challenge of combining vaccinia-based virotherapy with immunotherapy, are discussed as special focus.

To curb the pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), multiple platforms have been employed toward a safe and highly effective vaccine. Here, we develop a novel cell-based vaccine candidate, namely K562-S, by utilizing human cell K562 as a cellular carrier to display Spike (S) protein of SARS-CoV-2 on the membrane. Analogous to the traditional inactivated vaccine, K562-S cells can be propagated to a large scale by culturing and completely lose their viability after exposure to X-ray irradiation or formalin. We in turn demonstrated high immunogenicity of formalin-inactivated K562-S vaccine in both mouse and non-human primates and its protective efficacy in mice. In mice, immunization with inactivated K562-S vaccines can elicit potent neutralizing antibody (nAb) responses persisting longer than 5 months. We consequently showed in a hACE2 mouse model of SARS-CoV-2 infection that a two-shot vaccination with adjuvanted K562-S rendered greater than 3 log reduction in viral lung load and concomitant ameliorated lung pathology. Of importance, the administration of the same regimen in non-human primates was able to induce a neutralizing antibody titer averaging three-fold higher relative to human convalescent serum. These results together support the promise of K562-based, S-protein-expressing vaccines as a novel vaccination approach against SARS-CoV-2. Importantly, with a powerful capacity to carry external genes for cell-based vectors, this platform could rapidly generate two- and multiple-valent vaccines by incorporating SARS-CoV-2 mutants, SARS-CoV, or MERS-CoV.

现行抗反转录病毒治疗药物的联合应用可有效抑制艾滋病进程并显著延长患者寿命,但由于人类免疫缺陷病毒1型(human immunodeficiency virus type 1,HIV-1)潜伏库的存在,艾滋病迄今尚无法治愈.近年发现抗HIV广谱中和抗体能有效降低患者体内病毒载量并延缓疾病进程,为研发艾滋病疫苗和治愈策略带来了曙光,尤其是序贯免疫策略的使用极大推进了广谱中和抗体的开发和应用进程.2018年,美国食品药品管理局(Food and Drug Administration,FDA)批准了第1个临床应用的广谱中性单克隆和抗体,无疑为抗HIV单克隆抗体药物的研发注入了一支强心剂.本文围绕近年来抗HIV广谱中和抗体的研究进展进行综述,探讨未来广谱中和抗体研发面临的挑战.