COVID-19

Why is there still no HIV vaccine when there was enough in a year to develop several against Covid-19?

Forty years after the first AIDS warning on June 5, 1981, there is still no AIDS vaccine. There is no cure for AIDS: people with HIV have to undergo treatment for their entire lives. Conversely, the researchers managed to conduct an exceptional race against the clock against the coronavirus. In less than a year, several Covid-19 vaccines have been authorized. How can this discrepancy be explained?

In fact, HIV and coronavirus are two very different viruses, explains Christine Ruziu, Professor Emeritus of Virology at the Faculty of Medicine. René-Descartes (Necker Hospital), member of the National Academy of Medicine and the National Academy of Pharmacy.

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Can you remember what HIV is? How does this virus work in the body?

HIV (Human Immunodeficiency Virus) is a virus that infects cells of the immune system – lymphocytes. Its peculiarity lies in the integration of its genetic material into the chromosome of infected cells. HIV is a lentivirus that slowly destroys the immune system and gradually leads to AIDS (acquired immunodeficiency syndrome). In this case, the body is vulnerable to multiple opportunistic infections (toxoplasmosis, pneumocystosis, cryptococcosis, etc.).

Since lymphocytes are cells that play an extremely important role in the immune system, they are always active. However, once they become active, they produce a virus. Thus, the replication of the virus continues.

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Antiretroviral therapy and their combination in triple therapy only help to block the virus from multiplying. These lifelong therapies prevent the progression of infection to AIDS, but they do not kill infected cells and therefore do not kill the virus. Infected lymphocytes enter a dormant state and are not recognized as infected, so they cannot be removed. This is the main obstacle to this infection. It is also an obstacle to therapeutic vaccination.

Is this the reason why there is no AIDS vaccine today?

This virus constantly interferes with immune responses, it bypasses them. All vaccine methods that have been tested so far have failed to create an effective vaccine, including adenovirus vaccines (which use a live virus but are rendered harmless to carry some of the DNA. Another virus, in this case HIV, into cells to elicit an immune response) …

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