Background: The Omicron variant has become the most prevalent SARS-CoV-2 variant. Omicron is known to induce milder lesions compared to the original Wuhan strain. Fatal infection of the Wuhan strain into the brain has been well documented in COVID-19 mouse models and human COVID-19 cases, but apparent infections into the brain by Omicron have not been reported in human adult cases or animal models. In this study, we investigated whether Omicron could spread to the brain using K18-hACE2 mice susceptible to SARS-CoV-2 infection. Results: K18-hACE2 mice were intranasally infected with 1 × 105 PFU of the original Wuhan strain and the Omicron variant of SARS-CoV-2. A follow-up was conducted 7 days post infection. All Wuhan-infected mice showed > 20% body weight loss, defined as the lethal condition, whereas two out of five Omicron-infected mice (40%) lost > 20% body weight. Histopathological analysis based on H&E staining revealed inflammatory responses in the brains of these two Omicron-infected mice. Immunostaining analysis of viral nucleocapsid protein revealed severe infection of neuron cells in the brains of these two Omicron-infected mice. Lymphoid depletion and apoptosis were observed in the spleen of Omicron-infected mice with brain infection. Conclusion Lethal conditions, such as severe body weight loss and encephalopathy, can occur in Omicron-infected K18-hACE2 mice. Our study reports, for the first time, that Omicron can induce brain infection with lymphoid depletion in the mouse COVID-19 model.

AIM: In order to bridge the gap between pharmacogenomic research and its clinical application, we propose the concept of genetic electronic identity, named "GeneFace", and developed an electronic information system which integrated "drug-gene" interactions and recommendations for personalized medicine. METHODS: Based on the self-developed Precision Medicine knowledgebase, which concludes drug directions, guidelines or important literatures with high level of evidence, we developed GeneFace with Java-based open-resource application framework Spring Boot, further developed a mobile App with cross-platform framework Uni-APP. RESULTS: The App includes six modules: genetic testing appointment, genetic knowledge introduction, individualized medication advice, medication records, Geneface interpretation, and Precision Medicine knowledgebase. By detecting the genotype of more than 300 gene loci upon first use, users import the results to form a personal "drug-gene identity card". Then scan or enter the drug name in "GeneFace", the App would automatically give corresponding medication recommendations, including: risks for possible adverse drug reactions, risks for reducing the efficacy or even ineffectiveness, and possibility for dose adjustment, etc., which increase the safety of clinical drug use. People can obtain pharmacogenomics knowledge and basic drug information in the "GeneFace" app. CONCLUSION: Development as a digital therapeutic product, the expanded application of GeneFace can rapidly promote clinical applications of basic pharmacogenomics research and significantly improve drug use safety, which creating a new model for accelerating the clinical application of personalized medicine.