Malaria: New knowledge about naturally acquired immunity may improve
vaccines

Date:
November 12, 2021
Source:
University of Copenhagen - The Faculty of Health and Medical
Sciences
Summary:
When you have become immune to malaria after having contracted the
disease, it seems that the body uses a more efficient protection
than if you have been vaccinated against the deadly disease. The
researchers believe the new findings may be used to improve existing
malaria vaccines.



FULL STORY ==========================================================================
Each year, about half a million children in Africa die from
malaria. Infection with the malaria parasite is such a widespread
and deadly disease that scientists all over the globe are working to
understand it better in order to be able to fight it.


==========================================================================
Now, researchers from the University of Copenhagen have come a significant
step closer, as they have found an important difference between naturally acquired immunity and immunity following vaccination.

"The antibodies which the body produces when you have been infected with malaria look different from those produced by the body when you have
been vaccinated. And that probably means that our immune system has a
more efficient response when we have been naturally infected than when
we are vaccinated against malaria," says Lars Hviid, Professor at the Department of Immunology and Microbiology.

"Natural killer cells" The immune system can trigger various mechanisms
in order to defend the body.

The usual defence against infections with parasites, viruses and bacteria consists of so-called macrophages.

"When we are exposed to an attack from the outside, the immune system
can produce antibodies that attach to the foreign body that needs to
be fought.

They are then recognised by some small cells called macrophages, which
are attracted to the antibody and eat the bacterium or virus. This is
basically how immunity to most infectious diseases works," explains
Lars Hviid.



==========================================================================
But, now, researchers have discovered that immunity to malaria seems to
work differently. Here, the body's immune system uses some other types
of cells to fight an infection with the malaria parasite.

"We have found that the antibodies look different, depending on whether
you have been vaccinated or infected. And that means that the body
launches some other defence mechanism as, instead, it uses what we call
natural killer cells," says Lars Hviid.

More in common with cancer Natural killer cells are usually known to researchers as one of the body's best weapons to fight cancer cells. But,
now, it seems that the defence against malaria has features in common
with the immune system against cancer.

"In popular terms, you could say that the immune system has a
more tailored defence against malaria than against other typical
infections. Maybe we have evolved in this way because it is such a
contagious and deadly disease -- that is difficult to guess," says
Lars Hviid.

The researchers made the findings by comparing blood samples from Ghanaian people who had been infected with malaria with blood samples from people
who participated in Phase 1 clinical trials of an experimental malaria
vaccine.

He explains that the new knowledge may be used to develop new and improved malaria vaccines.

"Our study points to a new strategy for developing even better malaria
vaccines in the future. Because, now, we know how the body mobilises the defence with natural killer cells, and we can imitate that with vaccines,"
he says.

He looks forward to being able to test -- together with other researchers
- - whether a future malaria vaccine will be able to utilise natural
killer cells instead of the macrophages that the current vaccines use.

========================================================================== Story Source: Materials provided by University_of_Copenhagen_-_The_Faculty_of_Health_and
Medical_Sciences. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Mads Delbo Larsen, Mary Lopez-Perez, Emmanuel Kakra Dickson, Paulina
Ampomah, Nicaise Tuikue Ndam, Jan Nouta, Carolien A. M. Koeleman,
Agnes L. Hipgrave Ederveen, Benjamin Mordmu"ller, Ali Salanti,
Morten Agertoug Nielsen, Achille Massougbodji, C. Ellen van der
Schoot, Michael F. Ofori, Manfred Wuhrer, Lars Hviid, Gestur
Vidarsson. Afucosylated Plasmodium falciparum-specific IgG is
induced by infection but not by subunit vaccination. Nature
Communications, 2021; 12 (1) DOI: 10.1038/s41467-021- 26118-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211112121457.htm

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