The official guide for laboratory testing for coronavirus disease in suspected human cases by the WHO explains the procedure for testing a sample. On page two it states that the test

is based on detection for unique sequences of virus RNA by NAAT such as rRT-PCR with confirmation by nucleic acid sequencing when necessary.

As a layman I'm trying to understand how this works and specifically it this test involves the host's DNA or RNA. I understand that viruses attack and modify the host's DNA to get the host to make more copies of the virus.

Does the PCR test explained above target DNA/RNA of the host or does it attempt to find intact instances of SARS-CoV-2 RNA itself -- before it befalls a host's cell? It tries to identify the presence of the virus but does it do it on infected human genes or does it do it on the original virus?

  • 1
    The virus befalls the host cell. Some integrate their viral genome into the hosts DNA, SARS-CoV-2 does not do that. However, the host cell‘s machinery, which can not differentiate between foreign and own genome, then uses the virus‘ genome to produce (viral) mRNA. This RNA is then detected with the RT-PCR test. This only works if the virus has befallen a cell because SARS-CoV-2 does not have this machinery by itself, it needs to make use of our enzymes.
    – Narusan
    Commented Jul 24, 2020 at 7:09
  • The viral mRNA then gets turned into viral proteins by the host again, these viral proteins accumulate, generate a new virus, are able to leave the host cell and can infect other cells. Antibody tests test against these viral proteins.
    – Narusan
    Commented Jul 24, 2020 at 7:10
  • @Narusan That sounds like it answers the question and should not be a mere comment.
    – bitmask
    Commented Jul 24, 2020 at 11:17


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