Using a reverse genetic system, researchers mapped SARS-CoV-2 infection.

On May 27, Ralph Baric of the University of North Carolina (UNC) led a team that developed a reverse genetic system of SARS-CoV-2, providing new insights into the mechanisms by which disease progresses and severity after infectionThe findings were published in the journal CellThe reverse genetic system in virology usually refers to the ability to modify the genetic characteristics of the virus by cloning the full-length genome cDNA of the virus to the vector and copying the modified sub-virus in the cellBaric team is the ancestor of the development of coronavirus reverse technologyIn the latest study, they built an infectious clone of SARS-CoV-2 and a recombinant new coronavirus that expresses nano-luciferase (nLucerase), establishing a high-throughput, accurate neutralizing antibody detection methodspecifically, the researchers used different SARS-CoV-2 isolates to see how they effectively infected cultured cells in different parts of the human respiratory tractThey found a significant pattern of continuous change , SARS-CoV-2 , which showed a decreasing rate of infection in the human respiratory tract from the nasal cavity to the endothelial cells of the alveoliresearchers also found that ACE2 (the cell surface receptor used by the virus to enter cells) was expressed higher in the nasal epithelial cells, significantly higher than the throat, trachea, bronchial, end bronchial, and alveoli epithelial levelsThis difference may at least partly explain why the nasal epithelial cells are more susceptible to infectionresearchers further tested tmPRSS2 and Furin, two protein lysis enzymesThese enzymes are present in human cells, and SARS-CoV-2 uses them to reshape the necessary viral proteins and enter human cells for infectionIt turns out that when the levels of these enzymes rise, the ability to infect cells and replicate increasesThe team mapped several cases of lung infection in patients who died of COVID-19 and found that even though SARS-CoV-2 had about 75 percent of the sequence inovirus with SARS-CoV, the previously described neutralizing antibodies against MERS-CoV and SARS-CoV did not neutralise SARS-CoV-2However, serum in two of the five SARS patients in 2002 showed low levels of serum but had significant ability to contract SARS-CoV-2 infection in neutralized and cultured cellsThese data suggest that people who have been exposed to other coronaviruses may carry other types of antibodies in their blood that can at least partially protect them from SARS-CoV-2 infectionIn summary, the study found that the recombinant virus prepared by reverse genetics was consistent with the replication level of wild viruses in cell lines, and demonstrated the enhanced effect of protease TMPRSS2 and Furin on the replication of SARS-CoV-2In addition, SARS-CoV-2 has a decreasing rate of infection in human respiratory tract sepsis from the nasal cavity to the endoscopic epithelial cells Cross-neutralized the production of ANTIbodies to SARS-CoV may be a low-probability event in people infected with the new crown virus these findings open up new directions for future research on SARS-CoV-2, which could guide drug development and reduce THE spread of COVID-19