Although inoculation of COVID-19 vaccines has rolled out globally, there is still a critical need for safe and effective vaccines to ensure fair and equitable supply for all countries. Here, we report on the development of a highly efficacious mRNA vaccine, SW0123 that is composed of sequence-modified mRNA encoding the full-length SARS-CoV-2 Spike protein packaged in core–shell structured lipopolyplex (LPP) nanoparticles. SW0123 is easy to produce using a large-scale microfluidics-based apparatus. The unique core–shell structured nanoparticle facilitates vaccine uptake and demonstrates a high colloidal stability, and a desirable biodistribution pattern with low liver targeting effect upon intramuscular administration. Extensive evaluations in mice and nonhuman primates revealed strong immunogenicity of SW0123, represented by induction of Th1-polarized T cell responses and high levels of antibodies that were capable of neutralizing not only the wild-type SARS-CoV-2, but also a panel of variants including D614G and N501Y variants. In addition, SW0123 conferred effective protection in both mice and non-human primates upon SARS-CoV-2 challenge. Taken together, SW0123 is a promising vaccine candidate that holds prospects for further evaluation in humans.

Respiratory syncytial virus (RSV) infects small foci of respiratory epithelial cells via infected droplets. Infection induces expression of type I and III interferons (IFNs) and proinflammatory cytokines, the balance of which may restrict viral replication and affect disease severity. We explored this balance by infecting two respiratory epithelial cell lines with low doses of recombinant RSV expressing green fluorescent protein (rgRSV). A549 cells were highly permissive, whereas BEAS-2B cells restricted infection to individual cells or small foci. After infection, A549 cells expressed higher levels of IFN-β-, IFN-λ-, and NF-κB-inducible proinflammatory cytokines. In contrast, BEAS-2B cells expressed higher levels of antiviral interferon-stimulated genes, pattern recognition receptors, and other signaling intermediaries constitutively and after infection. Transcriptome analysis revealed that constitutive expression of antiviral and proinflammatory genes predicted responses by each cell line. These two cell lines provide a model for elucidating critical mediators of local control of viral infection in respiratory epithelial cells. Airway epithelium is both the primary target of and the first defense against respiratory syncytial virus (RSV). Whether RSV replicates and spreads to adjacent epithelial cells depends on the quality of their innate immune responses. A549 and BEAS-2B are alveolar and bronchial epithelial cell lines, respectively, that are often used to study RSV infection. We show that A549 cells are permissive to RSV infection and express genes characteristic of a proinflammatory response. In contrast, BEAS-2B cells restrict infection and express genes characteristic of an antiviral response associated with expression of type I and III interferons. Transcriptome analysis of constitutive gene expression revealed patterns that may predict the response of each cell line to infection. This study suggests that restrictive and permissive cell lines may provide a model for identifying critical mediators of local control of infection and stresses the importance of the constitutive antiviral state for the response to viral challenge.

Herpes simplex virus type 1 (HSV-1) is a prevalent human pathogen that infects over 3.72 billion individuals worldwide and can cause potentially blinding recurrent corneal herpetic disease. HSV-1 establishes latency within sensory neurons of trigeminal ganglia (TG) and TG-resident CD8+ T cells play a critical role in preventing its reactivation. The repertoire, phenotype and function of protective CD8+ T cells are unknown. Bolstering the apparent feeble numbers of CD8+ T cells in TG remains a challenge for immunotherapeutic strategies. In this study, a comprehensive panel of 467 HLA-A*0201-restricted CD8+ T cell epitopes were predicted from the entire HSV-1 genome. CD8+ T cell responses to these genome-wide epitopes were compared in HSV-1 seropositive symptomatic (SYMP) individuals (with a history of numerous episodes of recurrent herpetic disease) vs. asymptomatic (ASYMP) individuals (who are infected but never experienced any recurrent herpetic disease). Frequent polyfunctional HSV-specific effector memory IFN-γ+CD107a/b+CD44highCD62LlowCD8+ TEM cells were detected in ASYMP individuals and were mainly directed against three “ASYMP” epitopes. In contrast, SYMP individuals have more mono-functional central memory CD44highCD62LhighCD8+ TCM cells. Furthermore, therapeutic immunization with an innovative prime/pull vaccine, based on priming with multiple “ASYMP” epitopes (prime) and neurotropic TG delivery of the T-cell attracting chemokine CXCL-10 (pull), boosted the number and function of CD44highCD62LlowCD8+ TEM and tissue-resident CD103highCD8+ TRM cells in TG of latently infected HLA-A*0201 Tg mice and reduced recurrent ocular herpes following UV-B induced reactivation. These findings have profound implications in the development of T-cell-based immunotherapeutic strategies to treat blinding recurrent herpes infection and disease.

Herpes simplex virus 1 (HSV-1) glycoprotein B (gB)-specific CD8؉ T cells protect mice from herpes infection and disease. However, whether and which HSV-1 gB-specific CD8؉ T cells play a key role in the "natural" protection seen in HSV-1-seropositive healthy asymptomatic (ASYMP) individuals (who have never had clinical herpes disease) remain to be determined. In this study, we have dissected the phenotypes and the functions of HSV-1 gB-specific CD8 O ver a billion individuals worldwide carry herpes simplex virus 1 (HSV-1), which causes a wide range of mild to life-threatening diseases (1-3). Although the virus reactivates from latency and is shed multiple times each year in body fluids (i.e., tears, saliva, and nasal and vaginal secretions), most reactivations are subclinical due to an efficient immune-mediated containment of the infection and disease (4-7). Thus, most infected individuals are asymptomatic (ASYMP) and do not present any apparent recurrent herpetic disease (e.g., cold sores, genital, or ocular herpetic disease). However, a small proportion of individuals experience endless recurrences of herpetic disease, usually multiple times a year, often necessitating continuous antiviral therapy (i.e., with acyclovir and derivatives) (8,9). In those symptomatic (SYMP) individuals, HSV-1 frequently reactivates from latency, reinfects the eyes, and may trigger recurrent and severe corneal herpetic disease, a leading cause of infectious corneal blindness in