Currently, an inactivated vaccine has been widely used with encouraging results as a prophylactic agent against COVID-19 infection, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants. However, in vitro SARS-CoV-2 vaccine-specific immune features remain elusive, hindering the promotion of a third dose of the vaccine. Here, we present a detailed in vitro immune cellular response and large-scale multi-omics analysis for peripheral blood mononuclear cells (PBMCs) from participants vaccinated with CoronaVac (Sinovac Life Sciences, Beijing, China) and recovered participants from COVID-19. The mean titers of SARS-CoV-2 serum-neutralizing antibodies were significantly increased after the boosting immunization (Day 45) compared to the unimmunized state. We observed that type-1 helper T cells (Th1) tended to dominate after the first dose of vaccine, while humoral immune responses became dominant after the second dose due to the activation of type-2 helper T cell (Th2), memory B cells, and plasmablasts. T follicular helper cells (Tfh) involved in antibody production were activated after the first dose and were maintained for the observed time points. Single-cell RNA sequencing of PBMCs revealed specific changes in cell compositions and gene expression in immunized participants. Multi-omics analysis also demonstrated that CoronaVac-specific serum proteins, plasma metabolites, and plasma lipid changes were skewed to those changes in convalescent patients. Collectively, we provide a comprehensive understanding of CoronaVac-specific in vitro immune features.

Ribonucleic acid (RNA) viruses pose heavy burdens on public-health systems. Synthetic biology holds great potential for artificially controlling their replication, a strategy that could be used to attenuate infectious viruses but is still in the exploratory stage. Herein, we used the genetic-code expansion technique to convert Enterovirus 71 (EV71), a prototypical RNA virus, into a controllable EV71 strain carrying the unnatural amino acid (UAA) Nε-2-azidoethyloxycarbonyl-L-lysine (NAEK), which we termed an EV71-NAEK virus. After NAEK supplementation, EV71-NAEK could recapitulate an authentic NAEK time- and dose-dependent infection in vitro, which could serve as a novel method to manipulate virulent viruses in conventional laboratories. We further validated the prophylactic effect of EV71-NAEK in two mouse models. In susceptible parent mice, vaccination with EV71-NAEK elicited a strong immune response and protected their neonatal offspring from lethal challenges similar to that of commercial vaccines. Meanwhile, in transgenic mice harboring a PylRS-${\mathrm{tRNA}}_{\mathrm{CUA}}^{\mathrm{Pyl}}$ pair, substantial elements of genetic-code expansion technology, EV71-NAEK evoked an adjustable neutralizing-antibody response in a strictly external NAEK dose-dependent manner. These findings suggested that EV71-NAEK could be the basis of a feasible immunization program for populations with different levels of immunity. Moreover, we expanded the strategy to generate controllable coxsackieviruses for conceptual verification. In combination, these results could underlie a competent strategy for attenuating viruses and priming the immune system via artificial control, which might be a promising direction for the development of amenable vaccine candidates and be broadly applied to other RNA viruses.

In this protocol, we describe how to utilize the unnatural amino acid (UAA) incorporation system to read through endogenous premature termination codons in a Duchenne muscular dystrophy mouse model. We detail how to screen and optimize tRNA-enzyme pairs for efficient UAA incorporation, deliver the system intraperitoneally or intramuscularly in pathogenic mice by an adeno-associated viral (AAV) vector, and evaluate the restoration of endogenous dystrophin and increase in muscle strength after AAV injection.

SUMMARY: Cancer develops through a gradual accumulation of mutations including nonsense mutations in tumor suppressor genes (TSGs), which drive tumor proliferation and progression due to the impairment or complete loss of tumor suppressor protein function. The ability to restore functional tumor suppressor protein from mutant driver TSGs is a longstanding aspiration in cancer therapy, however, current strategies face formidable challenges in recovering proteins harboring heterogeneous mutations and circumventing dominant-negative effects exerted by endogenous mutant proteins. Therefore, the development of therapeutic interventions that are effective and generalizable across diverse nonsense mutations in cancer, to rescue endogenous mutant tumor suppressor proteins remains an urgent yet unmet need. Here we find that engineered suppressor transfer RNA (sup-tRNA) could overcome nonsense mutations in key driver tumor suppressor genes, such as TP53 , thereby avoiding the dominant-negative effects through the restoration of endogenous mutant p53 with its original functions. Optimized sup-tRNA that we named super tRNA, enabling high-fidelity incorporation of desired amino acids, can further enhanced the transcriptional activity of p53 to suppress tumor cell proliferation. Moreover, we also establish a computational model to guide super tRNAs design, and demonstrate that super tRNA could effectively inhibit tumor growth by targeted readthrough of nonsense mutations in different tumor suppressor genes. In two xenograft models harboring nonsense mutant TP53 , we observed up to a 70% reduction in tumor volume after lipid nanoparticle (LNP)-based sup-tRNA treatment, along with robust recovery of p53 expression and function, and no hematological or histological abnormalities detected. Our findings demonstrate the potential of sup-tRNA as a feasible and effective strategy to rescue and enhance tumor suppressor protein function, thereby preventing cancer development. As a novel therapeutic RNA, sup-tRNA provides a flexible strategy for targeting driver mutations in cancer, thereby expanding the potential of tRNA-based therapy in precision oncology.

The frequent emergence of drug resistance during the treatment of influenza A virus (IAV) infections highlights a need for effective antiviral countermeasures. Here, we present an antiviral method that utilizes unnatural amino acid-engineered drug-resistant (UAA-DR) virus. The engineered virus is generated through genetic code expansion to combat emerging drug-resistant viruses. The UAA-DR virus has unnatural amino acids incorporated into its drug-resistant protein and its polymerase complex for replication control. The engineered virus can undergo genomic segment reassortment with normal virus and produce sterilized progenies due to artificial amber codons in the viral genome. We validate in vitro that UAA-DR can provide a broad-spectrum antiviral strategy for several H1N1 strains, different DR-IAV strains, multidrug-resistant (MDR) strains, and even antigenically distant influenza strains (e.g., H3N2). Moreover, a minimum dose of neuraminidase (NA) inhibitors for influenza virus can further enhance the sterilizing effect when combating inhibitor-resistant strains, partly due to the promoted superinfection of unnatural amino acid-modified virus in cellular and animal models. We also exploited the engineered virus to achieve adjustable efficacy after external UAA administration, for mitigating DR virus infection on transgenic mice harboring the pair, and to have substantial elements of the genetic code expansion technology, which further demonstrated the safety and feasibility of the strategy. We anticipate that the use of the UAA-engineered DR virion, which is a novel antiviral agent, could be extended to combat emerging drug-resistant influenza virus and other segmented RNA viruses.

Ribonucleic acid (RNA) viruses pose heavy burdens on public-health systems. Synthetic biology holds great potential for artificially controlling their replication, a strategy that could be used to attenuate infectious viruses but is still in the exploratory stage. Herein, we used the genetic-code expansion technique to convert Enterovirus 71 (EV71), a model of RNA virus, into a controllable EV71 strain carrying the unnatural amino acid (UAA) Nε-2-azidoethyloxycarbonyl-L-lysine (NAEK), which we termed an EV71-NAEK virus. EV71-NAEK could recapitulate an authentic NAEK time- and dose-dependent infection in vitro and in vivo , which could serve as a novel method to manipulate virulent viruses in conventional laboratories. We further validated the prophylactic effect of EV71-NAEK in two mouse models. In susceptible parent mice, vaccination with EV71-NAEK elicited a strong immune response and potentially protected their neonatal offspring from lethal challenge similar to that of commercial vaccines. Meanwhile, in transgenic mice harboring a PylRS-tRNA ^Pyl pair, substantial elements of genetic-code expansion technology, EV71-NAEK evoked an adjustable neutralizing-antibody response in a strictly external NAEK dose-dependent manner. These findings suggested that EV71-NAEK could be the basis of a feasible immunization program for populations with different levels of immunity. Moreover, we expanded the strategy to generate controllable coxsackieviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for conceptual verification. In combination, these results could underlie a competent strategy for attenuating viruses and priming the immune system via artificial control, which might be a promising direction for the development of amenable vaccine candidates and be broadly applied to other RNA viruses.