2023-12-14 17:24:12
One to two weeks following contracting Covid-19, the SARS-CoV-2 virus generally becomes undetectable in the upper respiratory tract. However, this does not necessarily mean that the virus is no longer present in the body. These are the conclusions of a team of researchers from the Institut Pasteur, in collaboration with the Atomic Energy and Alternative Energies Commission (CEA). This study was carried out on animal lung cells.
Persistence of SARS-CoV-2: the role of viral reservoirs
This study, published on November 2, 2023 in the scientific journal Nature Immunologyshows that not only can SARS-CoV-2 stay in the lungs for up to 18 months, but that this might be linked to defects in natural immunity.
Innate or natural immunity is immunity that is present from birth and “does not need to be learned through exposure to an invader,” explains the MSD manual. Who specifies: “It thus provides an immediate response to foreign invaders. However, its components treat all foreign invaders in a similar manner. They recognize only a limited number of identifying substances (antigens) on foreign invaders. These antigens are, however, present on many foreign invaders. Unlike acquired immunity, innate immunity does not remember its encountersdoes not memorize particular foreign antigens or maintain protection once morest future infections.”
Some viruses remain in the body discreetly and undetectably following causing an infection. They are present in what are called “viral reservoirs”. This is particularly the case for HIV, which remains latent in certain immune cells and can reactivate at any time. This might therefore also be the case for the SARS-CoV-2 virus, which causes Covid-19.
Persistence of the virus: it is more important with Omicron
This hypothesis was put forward by researchers at the Pasteur Institute in 2021 and was therefore confirmed by their study published on November 2, 2023. “We observed that inflammation persists for a long time in primates that have been infected with SARS-CoV -2. Therefore, we suspect that this is due to the presence of the virus in the body”, explains the head of the HIV, inflammation and persistence department at the Pasteur Institute Michaela Müller-Trutwin.
Scientists also discovered that the amount of virus persisting in the lungs was less with the Omicron variant than with the original virus. “We were really surprised to find viruses in certain immune cells – alveolar macrophages – following such a long period and when regular PCR tests were negative,” adds Nicolas Huot, the first author of the study, also a researcher in the HIV, inflammation and persistence department of the Pasteur Institute.
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