RESUMEN
The global spread of SARS-CoV-2 is posing major public health challenges. One unique feature of SARS-CoV-2 spike protein is the insertion of multi-basic residues at the S1/S2 subunit cleavage site, the function of which remains uncertain. We found that the virus with intact spike (Sfull) preferentially enters cells via fusion at the plasma membrane, whereas a clone (Sdel) with deletion disrupting the multi-basic S1/S2 site instead utilizes a less efficient endosomal entry pathway. This idea was supported by the identification of a suite of endosomal entry factors specific to Sdel virus by a genome-wide CRISPR-Cas9 screen. A panel of host factors regulating the surface expression of ACE2 was identified for both viruses. Using a hamster model, animal-to-animal transmission with the Sdel virus was almost completely abrogated, unlike with Sfull. These findings highlight the critical role of the S1/S2 boundary of the SARS-CoV-2 spike protein in modulating virus entry and transmission.
RESUMEN
Objective The staffs of biosafety level 3 laboratories (BSL-3) face with the stress of handling highly pathogenic microbs and special laboratory environment.The job stress may result in accidents in the laboratory as negative factor for the risk control.The research may provide support for the control of risk in biosafety laboratories.Methods In order to assess the job stress in the staff in BSL-3 laboratory, we modified “the Chinese simple job stress questionnaire”based on the theory of the JDC mode and ERI mode, and an investigation was carried out.The present study included the staffs (87 employees) from six BSL-3 laboratories located in five provinces ( Shanghai, Zhejiang, Jiangsu, Fujian and Wuhan) .Results Analysis of the data indicates that variables of age, working years, job duties, manipulating of animals, type of microorganisms and transmission route have a significant influence on the level of job stress in BSL-3 laboratory.Conclusion The BSL-3 laboratory staff in higher stress level have the characteristicses:20-39 years old, short work years, regular staff, operating on air-borne microbiology, manipulating of animals and operating on one more microbiology.
