Human embryos could be at the risk of SARS-CoV-2 virus in as early as the second week of pregnancy if the would-be-mom is Covid-19 positive, according to a study published in the Royal Society’s journal ‘Open Biology’.
Conducted by the scientists from the University of Cambridge and the California Institute of Technology (Caltech), the study said that genes that are thought to play a role in how the Coronavirus infects our cells have been found to be active in embryos as early as during the second week of pregnancy.
“This could mean embryos are susceptible to COVID-19 if the mother gets sick, potentially affecting the chances of a successful pregnancy,’ said the scientists.
To examine the risks, they used technology developed by Professor Magdalena Zernicka-Goetz at the University of Cambridge to culture human embryos through the stage they normally implant in the body of the mother to look at the activity - or ‘expression’ - of key genes in the embryo.
On the surface of the SARS-CoV-2 virus are large ‘spike’ proteins. Spike proteins bind to ACE2, a protein receptor found on the surface of cells in our body. Both the spike protein and ACE2 are then cleaved, allowing genetic material from the virus to enter the host cell. The virus manipulates the host cell’s machinery to allow the virus to replicate and spread.
The researchers found patterns of expression of the genes ACE2, which provide the genetic code for the SARS-CoV-2 receptor, and TMPRSS2, which provides the code for a molecule that cleaves both the viral spike protein and the ACE2 receptor, allowing infection to occur.
These genes were expressed during key stages of the embryo’s development, and in parts of the embryo that go on to develop into tissues that interact with the maternal blood supply for nutrient exchange.
Gene expression requires that the DNA code is first copied into an RNA message, which then directs the synthesis of the encoded protein. The study reports the finding of the RNA messengers.
Professor Magdalena Zernicka-Goetz from the University of Cambridge and Caltech, said: “Our work suggests that the human embryo could be susceptible to Covid-19 as early as the second week of pregnancy if the mother gets sick.
“To know whether this really could happen, it now becomes very important to know whether the ACE2 and TMPRSS2 proteins are made and become correctly positioned at cell surfaces. If these next steps are also taking place, it is possible that the virus could be transmitted from the mother and infect the embryo’s cells.”