RESUMEN
Severe acute respiratory syndrome CoV-2 (SARS-CoV-2) caused the Corona Virus Disease 2019 (COVID-19) cases in China has become a public health emergency of international concern (PHEIC). Based on angiotensin converting enzyme 2 (ACE2) as cell entry receptor of SARS-CoV, we used the hACE2 transgenic mice infected with SARS-CoV-2 to study the pathogenicity of the virus. Weight loss and virus replication in lung were observed in hACE2 mice infected with SARS-CoV-2. The typical histopathology was interstitial pneumonia with infiltration of significant lymphocytes and monocytes in alveolar interstitium, and accumulation of macrophages in alveolar cavities. Viral antigens were observed in the bronchial epithelial cells, alveolar macrophages and alveolar epithelia. The phenomenon was not found in wild type mice with SARS-CoV-2 infection. The pathogenicity of SARS-CoV-2 in hACE2 mice was clarified and the Kochs postulates were fulfilled as well, and the mouse model may facilitate the development of therapeutics and vaccines against SARS-CoV-2.
RESUMEN
Objective:Semaphorin 4D (Sema4D) acts as a regulator for axon guidance in central nervous system development. However, new evidence indicates that Sema4D has a previously unrecognized function, namely, compensatory angiogenic factor. This study aimed to investigate the effect of Sema4D on tumor growth and vascularity of colorectal carcinoma (CRC) in nude mice. Meth-ods:Sema4D was knocked down in CRC cells by infecting the cells with lentiviruses coding for Sema4D shRNA. Two groups of cells, namely, those infected with control viruses and those infected with Sema4D shRNA viruses, were subjected to migration assay to test their ability induce endothelial cell migration. The two cell groups were subcutaneously injected into nude mice. Tumor growth was documented, and the tumors harvested from the mice were subjected to immunohistochemistry or immuno fl uorescence analyses. Re-sults:In vitro migration assay results indicated that media conditioned by HCT-116 cells infected with Sema4D shRNA lentiviruses in-duced low endothelial cell migration. The two groups of subcutaneously inoculated cells showed 100%tumorigenicity. However, tumor growth rates were significantly different between the two groups. Xenografts in which Sema4D was downregulated showed marked re-duction in tumor size and vascularity. Conclusion:Cancer cells may highly express Sema4D to trigger net neo-angiogenesis and gener-ate a tumor blood supply system. Thus, Sema4D could potentially be a target in anti-angiogenic therapy of CRC patients.