Immunizing Mosquitoes To Fight Malaria
By Jesse Emspak, International Business Times
Millions of people in the tropics suffer from malaria, a mosquito-borne disease that has been difficult to treat and which costs many developing countries millions of dollars per year in lost productivity. Up to now, efforts at controlling it have focused on attacking the parasites that cause it, keeping mosquitoes from biting, or killing the insects.
But at Johns Hopkins University, Rhoel Dinglasan, an entomologist and biologist, decided to try another tack: immunizing mosquitoes.
Mosquitoes carry a species of parasite called plasmodium. The parasite lives in the mosquito’s gut. The parasites then spread to the mosquito’s salivary glands, and when the insect bites an uninfected person, they enter the bloodstream. At that point the plasmodium goes from the blood to a person’s liver, where it matures, escaping to the bloodstream to infect the red blood cells in a form called a merozoite.
Once in the blood cells, the parasite reproduces until the red cell bursts, releasing more merozoites. This cycle repeating itself causes the characteristic fever, chills and ache associated with the disease.
…
When a mosquito bites an infected human, it takes up some of the gametocytes.They aren’t dangerous to people at that stage. Since plasmodium is vulnerable there, and that is the point that Dinglasan chose to attack.
Full story here
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Here’s the very first Press Release from Johns Hopkins university citing this idea:
Vaccine Blocks Malaria Transmission in Lab Experiments
Researchers at the Johns Hopkins Malaria Research Institute have for the first time produced a malarial protein (Pfs48/45) in the proper conformation and quantity to generate a significant immune response in mice and non-human primates for use in a potential transmission-blocking vaccine. Antibodies induced by Pfs48/45 protein vaccine effectively blocked the sexual development of the malaria-causing parasite, Plasmodium, as it grows within the mosquito. Sexual development is a critical step in the parasite’s life cycle and necessary for continued transmission of malaria from mosquitoes to humans. The study is published in the July 22 edition of the journal PLoS ONE.
“Development of a successful transmission-blocking vaccine is an essential step in efforts to control the global spread of malaria. In our study, we demonstrate the relative ease of expression and induction of potent transmission-blocking antibodies in mice and non-human primates. This approach provides a compelling rationale and basis for testing a transmission-blocking vaccine in humans,” said Nirbhay Kumar, PhD, senior author of the study and professor in Johns Hopkins Bloomberg School of Public Health’s W. Harry Feinstone Department of Molecular Microbiology and Immunology.
For the study, the research team expressed full-length Pfs48/45 in E. coli bacteria to produce the vaccine. Previous attempts to fully express the protein had not been successful. The vaccine was first given to mice in the laboratory. The vaccine was also tested in non-human primates (Olive baboons) in Kenya with similar results. According to the study, a single-dose vaccine provided a 93 percent transmission-blocking immune response, reaching greater than 98 percent after a booster given several months later.
“This is an exciting beginning to what might become an important tool in the arsenal for malaria control and progressive elimination of malaria transmission,” said Kumar. There is no animal reservoir for human malaria and in that regard it is possible to gradually reduce malaria transmission to a point of almost eradication. However, Kumar cautioned that more research is needed to achieve that goal. For one, similar research efforts are needed to reduce transmission of Plasmodium vivax, another major human malaria parasite.
Malaria affects greater than 500 million people worldwide and is estimated to kill over one million people each year, most of whom are children living in Africa.
In addition to Kumar, “A Potent Malaria Transmission-Blocking Vaccine Based on Condon Harmonized Full Length Pfs48/45 Expressed in E. Coli” was published by Debabani Roy Chowdhury, a postdoctoral fellow of the Johns Hopkins Bloomberg School of Public Health; Evelina Angov of the U.S. Military Malaria Vaccine Program; and Thomas Kariuki of the Institute of Primate Research in Nairobi, Kenya.
The research was supported by grants from the National Institutes of Health and the Johns Hopkins Malaria Research Institute.
My thanks to Biobob for pointing out the simple fact that only a few species carry malaria. It appears they have been exterminated in the U.S., as well as several other countries, prior to the effective ban of the otherwise harmless DDT used for that purpose. We used it to control blood-sucking flies, as well, spraying the exposed cattle about every month—not to mention each other from time to time. It is harmless to humans.
Mr Lynn says:
October 30, 2010 at 8:35 pm
“[…]
So vaccinating all the people (not the mosquitos!) in a malarial region might be a more effective medium-term solution than anything else. This research is not, as some above have portrayed it, a frivolous exercise at all.”
Yes, the vaccine would be a great tool in the fight against malaria infection. I just got my flu vaccination last Wednesday and the imagery that popped up – long lines of mosquitos awaiting their shots; in which shoulder? – was largely due to the title and intro of the article. Couldn’t help myself, thanks to the title.
/Mr Lynn
DDT kills too many things, but I don’t think surgically eliminating a few mosquito species would have much of an effect on the rest of the ecosystem. I’m not sure I know what I’m talking about, but I’m not sure anyone else does either. This is just based on common sense reasoning — things that eat mosquitos have many other food sources. I don’t understand why we cant use pheromones or something to prevent the little buggers from breeding, but I suppose there are reasons.
Mr Lynn and Biobob
Its good to see some sensible posting here. It does not take much to search for ddt to find it is not banned for vector control.
It is also interesting that it is not 100% safe for honey bees. (see trials from the 1950s).
It is not right to spread broad spectrum death on insects even if it is relatively safe for humans.
Many controls have been tried on other pests without sufficient research (cane toads in Aus is one).
To quote bob:
“DDT has never been banned for use on Malaria in the USA or anywhere else where it is needed. “
WilliMc says:
) However, the insect vector populations are much smaller and the Malaria infected human population is small enough so that the disease is not likely to be transmitted.
October 31, 2010 at 6:03 am
” …It appears they have been exterminated in the U.S., as well as several other countries, prior to the effective ban of the otherwise harmless DDT used for that purpose. ….It is harmless to humans.”
You all should understand that absolutely NO Malaria vectors have EVER been exterminated (completely deleted) anyplace where vector control has been administered except perhaps in some small and very isolated islands. The Anopheles mosquitoes are STILL present in the areas where Malaria historically occurred. (see
DDT does have harmful efffects on humans and mammals; it is just not as immediately toxic as Organochloride insecticides that have also been use restricted (banned). Lots of studies have shown endocrine effects.
All of the experts and nearly-expert can discuss and tell me that my intellect or education isn’t up to the task of understanding the issues in the malaria & mosquito dance, but I know this: malaria disappeared from North America as a consequence of killing off the mosquitoes who were infected with DDT. Many other nations, especially in the tropics had started excellent programs to do the same, but were persuaded or refused aid money to pay for DDT-based programs. Those nations which stopped their DDT programs have had millions of deaths since; nearby nations which have not discontinued the DDT have not had those extra deaths.
Complicated biochemistry and explanations thereof are very interesting and I confess I’ve learned a lot from “lurking” and reading here, about a lot of subjects. But, gentlemen and ladies, facts is facts – as my grandfather used to say – and just as Schmelling was KO’d by Joe Louis, the mosquito and malaria were being KO’d by DDT until some people stopped the use of DDT. My point? Kill the damned mosquitoes with what we know kills ’em and doesn’t kill humans. And what might that be? DDT.
The nice thing about these schemes is that those malaria strains which aren’t susceptible to the mosquito’s immunes response, will multiply to become the dominant population and then a new solution will be needed- ensuring employment for gene monkeys forever. Now what you don’t want to do is improve the living conditions of children so that they are healthier and can survive malaria infections. That sort of mollycoddling just sets a bad precedent. And contrary to what is says in the article, there is a wild animal reservoir for human malaria, it has recently been found in great apes.
Who’s to say that the vaccine won’t have deleterious effects on the environment? I would be pleasantly surprised if this works as planned but I’m still betting on DDT.
tm says:
October 30, 2010 at 6:47 am
Some combination of ego and money is involved, I’m sure.
Perhaps a big name has decreed embryonic stem cell research, and that is that. Grants and other funding will flow accordingly.
Or, maybe it’s the other way around. Grants and funding are coming the way of embryonic stem cell research and like salmon following a scent of home waters, the researchers are moving up those particular streams.
A lot of celebrity firepower came the embryonic way. I’m sure some money did to.
Malaria was essentially eliminated from the USA BEFORE the widespread use of DDT. Agreed, used as a persistent agent, it’s good at eliminating Anopheline mosquitoes, but mosquitoes have already evolved DDT resistance. Animals with high mutation rates & very short generations (such that 10 generations can occur in one calender year) can & do evolve resistance to chemicals, just as bacteria and viruses do.
No SINGLE approach is going to eliminate malaria in the tropics. Development, leading to clean water supplies inside the home and homes that are not wide open to mosquitoes, was a big part of how the USA & western Europe got rid of malaria. Consideration of draining some swampy areas that don’t serve a useful purpose in the local ecosystem should be in the picture. DDT & other pesticides should be in the picture. Bednets to protect people while they sleep are a solution that is cheap and can be applied immediately, and offers relatively little opportunity for graft on the part of greedy tyrannies in malarious parts of the world. This strategy is interesting and potentially workable, and might also contribute to an effective multi-pronged approach on the problem.
People in malarious regions are losing out economically because they are chronically mildly ill, so they can’t work as hard. There are pretty good estimates available as to the economic losses available. People in malarious regions are suffering daily family tragedies — babies, young children, and pregnant women are all more vulnerable to dying of malaria.
It seems that many of the regular commenters here are strong believers in human freedom. Well, helping people be healthy so they can get busy lifting themselves out of poverty sounds like a pretty good investment of research money to me, especially if it’s coming out of private pockets like the Bill and Melinda Gates Foundation. I’d like to see us, the free world, stop pushing our eco-craziness on people struggling in unimaginable poverty. But then again, AGW is, in my view, very racist, designed to keep the poorest people of the world poor by preventing them from accessing energy in the form of fossil fuels so they can’t lift themselves out of the crushing poverty they live in.