SARS-CoV-2 can infect human embryos

Area of Science:

• Reproductive Biology
• Virology
• Embryology

Background:

• The COVID-19 pandemic, caused by SARS-CoV-2, has raised concerns about its potential impact on human reproduction.
• While SARS-CoV-2 affects various organs, its effects on early human embryogenesis and pregnancy establishment are not well understood.

Purpose of the Study:

• To investigate the susceptibility of early human embryos to SARS-CoV-2 infection.
• To determine if key viral entry factors are present in preimplantation embryos.

Main Methods:

• RNA sequencing (RNA-seq) and immunofluorescence were used to detect SARS-CoV-2 entry factors (ACE2 and TMPRSS2) in blastocyst-stage embryos.
• Fluorescent reporter virions and live SARS-CoV-2 were used to assess viral entry and infection in human embryos.
• Blocking antibodies targeting the Spike (S) glycoprotein or ACE2 were employed to evaluate infection attenuation.

Main Results:

• ACE2 and TMPRSS2 were found to be co-expressed in trophectoderm cells of blastocyst-stage human embryos.
• Trophectoderm cells demonstrated robust infection by SARS-CoV-2 reporter virions, which was reduced by blocking antibodies.
• Exposure to live SARS-CoV-2 resulted in infection and compromised the health of human blastocysts.

Conclusions:

• Early human embryos, specifically trophectoderm cells, are susceptible to SARS-CoV-2 infection.
• This susceptibility has potential implications for reproductive health during and after the COVID-19 pandemic.
• The findings identify the early embryo as a novel human target tissue for SARS-CoV-2.