RESUMEN
The development of a tractable small animal model faithfully reproducing human coronavirus disease 2019 pathogenesis would arguably meet a pressing need in biomedical research. Thus far, most investigators have used transgenic mice expressing the human ACE2 in epithelial cells (K18-hACE2 transgenic mice) that are intranasally instilled with a liquid severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suspension under deep anesthesia. Unfortunately, this experimental approach results in disproportionate high central nervous system infection leading to fatal encephalitis, which is rarely observed in humans and severely limits this model's usefulness. Here, we describe the use of an inhalation tower system that allows exposure of unanesthetized mice to aerosolized virus under controlled conditions. Aerosol exposure of K18-hACE2 transgenic mice to SARS-CoV-2 resulted in robust viral replication in the respiratory tract, anosmia, and airway obstruction but did not lead to fatal viral neuroinvasion. When compared with intranasal inoculation, aerosol infection resulted in a more pronounced lung pathology including increased immune infiltration, fibrin deposition, and a transcriptional signature comparable to that observed in SARS-CoV-2infected patients. This model may prove useful for studies of viral transmission, disease pathogenesis (including long-term consequences of SARS-CoV-2 infection), and therapeutic interventions.
Asunto(s)
Enzima Convertidora de Angiotensina 2/genética , COVID-19/fisiopatología , Modelos Animales de Enfermedad , Encefalitis Viral/prevención & control , Queratina-18/genética , Rociadores Nasales , SARS-CoV-2/fisiología , Administración por Inhalación , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , COVID-19/inmunología , COVID-19/virología , Encefalitis Viral/mortalidad , Células Epiteliales/metabolismo , Femenino , Humanos , Queratina-18/metabolismo , Pulmón/inmunología , Pulmón/patología , Pulmón/fisiopatología , Masculino , Ratones , Ratones Transgénicos , Regiones Promotoras Genéticas/genética , Transcriptoma , Replicación ViralRESUMEN
The COVID-19 pandemic caused by SARS-CoV-2 has made the development of safe and effective vaccines a critical priority. To date, four vaccines have been approved by European and American authorities for preventing COVID-19, but the development of additional vaccine platforms with improved supply and logistics profiles remains a pressing need. Here we report the preclinical evaluation of a novel COVID-19 vaccine candidate based on the electroporation of engineered, synthetic cDNA encoding a viral antigen in the skeletal muscle. We constructed a set of prototype DNA vaccines expressing various forms of the SARS-CoV-2 spike (S) protein and assessed their immunogenicity in animal models. Among them, COVID-eVax-a DNA plasmid encoding a secreted monomeric form of SARS-CoV-2 S protein receptor-binding domain (RBD)-induced the most potent anti-SARS-CoV-2 neutralizing antibody responses (including against the current most common variants of concern) and a robust T cell response. Upon challenge with SARS-CoV-2, immunized K18-hACE2 transgenic mice showed reduced weight loss, improved pulmonary function, and lower viral replication in the lungs and brain. COVID-eVax conferred significant protection to ferrets upon SARS-CoV-2 challenge. In summary, this study identifies COVID-eVax as an ideal COVID-19 vaccine candidate suitable for clinical development. Accordingly, a combined phase I-II trial has recently started.