TMPRSS2 and infection: Viotti et al. collected trophectoderm cells from blastocyst-stage embryos donated to research after exposing them to the SARS-CoV-2 virus (infection by spinoculation with GFP-reporter pseudotyped virions) and discovered that the cells from the embryos expressed ACE2 receptor and TMPRSS2 protease are susceptible to the infection through the ACE2 receptor [31].