In reading about Malaria and the struggle to create a
vaccine against it I came across this article/chart about promising strategies
to create a vaccine. The parasites, of the Plasmodium
genus, that causes Malaria in humans has been around for hundreds to even
thousands of years. This disease has no vaccine but lots of research is being
done to find one. There are three strategies that are seen as promising in
possible vaccination.
The first is to grow genetically modified or irradiate
immature parasites in mosquitoes, extract them and then inject fragments into a
previously uninfected human. This would trigger an immune response in the human
and lead to the creation of anti-body against the parasite. With anti-body, IgE
is the class of anti-body that fights parasites, present and memory cells
developed if the person were to be infected with the parasite again hopefully
Malaria would not develop and the parasite would be killed quickly.
The next strategy is similar to the first strategy but
instead of altering the parasite, healthy parasite surface proteins are taken
and coupled with an adjuvant. The adjuvant will elicit an increased immune
response to the antigen, the foreign parasite surface proteins. This would be
followed up by a booster shot about two years later. This would also lead to
memory cell formation.
A vaccine for the mosquito itself would prevent the
transmission from person to person. How it is suppose to work is by creating a
human antibody against an enzyme in the mosquito critical to the proliferation
of the parasites. Taking parts of the enzyme aminopeptidase and injecting them
into a human would lead to the creation of anti-bodies against the enzyme. When
the immunized human is then bitten by a mosquito not only would the mosquito ingest
blood, but also antibody. This antibody would then bind to aminopeptidase prohibiting
the enzyme from performing its proper function in the proliferation of Malaria
causing parasites.
Each of these are very novel ways to try and vaccinate
against Malaria and hopefully one day soon they will be given to eradicate this
disease that has been around for so long. To combine a vaccination that not
only treats the human but also prevents transmission by, in a round-a-bout way,
immunizing the mosquito as well seems like an excellent way to not only protect
humans but maybe one day eliminate the parasite all together.
I agree with the importance of this topic. Malaria is a large global burden that rests on some of the countries shoulders least able to devote economic resources to developing treatment. I like the idea of developing vaccinations, as this may be the most cost effective way to tackle the issue. I looked for a paper on pubmed for recent vaccinations, and got excited when I found such an optimistic paper (Douglass et al). They seem to have found a protein to target in P. falciparum which can virtually eliminate that species. Howeverm the next article I found reminded me that life is not always so simple...(Mackinnon et al). They found in their animal model that vaccines eliminated some strains, but increased the overall virulence of the strains that were not affected by the vaccine. This reminds me that the implementation of new treatment outside of laboratories always has surprises in store.
ReplyDeleteAlexander D. Douglas, Andrew R. Williams, Joseph J. Illingworth, Gathoni Kamuyu, Sumi Biswas, Anna L. Goodman, David H. Wyllie, Cécile Crosnier, Kazutoyo Miura, Gavin J. Wright, Carole A. Long, Faith H. Osier, Kevin Marsh, Alison V. Turner, Adrian V.S. Hill, Simon J. Draper. The blood-stage malaria antigen PfRH5 is susceptible to vaccine-inducible cross-strain neutralizing antibody. Nature Communications, 2011; 2: 601 DOI: 10.1038/ncomms1615
Margaret J. Mackinnon, Andrew F. Read. Immunity Promotes Virulence Evolution in a Malaria Model. PLoS Biology, 2004; 2 (9): e230 DOI: 10.1371/journal.pbio.0020230