A Vaccine Alternative Protects Mice Against Malaria

English: A female mosquito of the Culicidae family (Culiseta longiareolata). Size: about 10mm length Location: Lisbon region, Portugal Türkçe: Culiseta longiareolata türü di?i bir sivrisinek. (Photo credit: Wikipedia)

English: A female mosquito of the Culicidae family (Culiseta longiareolata). Size: about 10mm length Location: Lisbon region, Portugal Türkçe: Culiseta longiareolata türü di?i bir sivrisinek. (Photo credit: Wikipedia)

Vectored immunoprophylaxis (VIP) injection triggers creation of antibodies that prevent malaria in 70 percent of mice

A study led by Johns Hopkins Bloomberg School of Public Health researchers found that injecting a vaccine-like compound into mice was effective in protecting them from malaria. The findings suggest a potential new path toward the elusive goal of malaria immunization.

Mice injected with a virus genetically altered to help the rodents create an antibody designed to fight the malaria parasite produced high levels of the anti-malaria antibody. The approach, known as Vector immunoprophylaxis, or VIP, has shown promise in HIV studies. It had never before been tested with malaria, for which no licensed vaccine exists.

A report on the research appears online Aug. 11 in the Proceedings of the National Academy of Sciences (PNAS).

Malaria is one of the world’s deadliest infectious diseases, killing as many as 1 million people per year, the majority of them children in Africa. Malaria patients get the disease from infected mosquitoes. Of the four types of malaria that affect humans, the parasite Plasmodium falciparum is the most lethal, responsible for the majority of malaria cases. Antimalarial treatments and mosquito habitat modification have contributed to a decline in malaria mortality. But the number of cases remains high, and stemming them is a top global health priority.

In their study, researchers used a virus containing genes that were encoded to produce an antibody targeted to inhibit P. falciparum infection. Up to 70 percent of the mice injected with the VIP were protected from malaria-infected mosquito bites. In a subset of mice that produced higher levels of serum antibodies, the protection was 100 percent. The mice were tested a year after receiving a single injection of the virus and were shown to still produce high levels of the protective antibody.

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Scientists Find Insect DEET Receptors, Develop Safe Alternatives to DEET

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UC Riverside research has large implications for controlling insect-borne diseases worldwide

Insects are repelled by N,N-diethyl-m-toluamide, also known as DEET.  But exactly which olfactory receptors insects use to sense DEET has eluded scientists for long.

Now researchers at the University of California, Riverside have identified these DEET-detecting olfactory receptors that cause the repellency — a major breakthrough in the field of olfaction.

Further, the team of researchers has identified three safe compounds that mimic DEET and could one day be used to prevent the transmission of deadly vector-borne diseases such as malaria, dengue, West Nile virus, and yellow fever.

Study results appear online Oct. 2 in Nature.

“Until now, no one had a clue about which olfactory receptor insects used to avoid DEET,” saidAnandasankar Ray, an associate professor of entomology, who led the research team.  “Without the receptors, it is impossible to apply modern technology to design new repellents to improve upon DEET.”

The method Ray’s team used to identify the receptors examined in an unbiased fashion all the sensory neurons in the insect, which was the key to successfully finding them.  In their experiments, the researchers used the genetic model system Drosophila melanogaster  (fruit fly) that was genetically engineered in such a way that neurons activated by DEET glowed fluorescent green.  The researchers thus found the receptors, called Ir40a receptors, lining the inside of a poorly studied region of the antenna called the sacculus.

Introduced in the 1940s, DEET has remained unchanged for the past 65 years largely because the receptor in insects for DEET was unknown. Capable of dissolving plastics and nylon, DEET has been reported to inhibit an enzyme (acetylcholinesterase) in mammals that is important in the nervous system. DEET is also unaffordable and inconvenient for use in Africa and other parts of the world where hundreds of millions of people suffer from insect-transmitted diseases.

“Our three compounds, which we tested rigorously in the lab, do not dissolve plastics,” Ray said.   “They are approved by the Food and Drug Administration for consumption as flavors or fragrances, and are already being used as flavoring agents in some foods.  But now they can be applied to bed-nets, clothes, curtains — making them ward off insects.”

Using novel chemical informatics strategies, Ray’s lab screened half a million compounds against the DEET receptor to identify substitutes.  A computer algorithm the team developed identified which compounds are not only predicted to be strong repellents but also found naturally in fruits, plants or animals.  The algorithm predicted nearly 200 natural DEET substitutes; of which the researchers tested ten compounds.  Of these, eight were strong repellents on flies, of which four were tested in Aedesmosquitoes and found to be strong repellents. Of the four compounds, three are already approved by the Food and Drug Administration as food additives.

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Genetic genocide: Genetically altered mosquito warriors could wipe out humanity’s biggest killer

English: Aedes aegypti in Dar es Salaam, Tanzania

Image via Wikipedia

Responsible for as many as 46 billion deaths over the history of our species

 
War, plague, famine, heart disease, cigarettes, road trauma: six very effective killers of human beings. But they’re all amateurs when their records are compared to the number one mass murderer of all time. The humble mosquito, and the deadly diseases it carries, is estimated to have been responsible for as many as 46 billion deaths over the history of our species. That staggering number is even more frightening in context – it means that mosquitoes are alleged to have killed more than half the humans that ever lived.

So if any creature has earned the full force of the wrath of humanity, this nasty little bugger is it. Especially certain species like Aedes aegypti mosquitoes – the world’s number one disease vector for deadly dengue fever, which infects between 50 and 100 million people a year around the world.

A. aegypti has evolved into the most curious and innocuous of human predators – it’s the females that bite, and they more or less only feed on humans. Each bite exposes the victim to any blood-borne pathogens that the mosquito might have picked up along its way. Dengue and yellow fevers are among the most common – the mosquito contracts the virus by biting an infected victim, and then injects it along with its saliva when it stabs the next unlucky target’s skin with its proboscis.

A. aegypti flies silently, so it’s hard to know when you’re in danger of being bitten, and it breeds and multiplies extremely effectively, needing only a teaspoon full of standing water for its larvae to hatch.

DDT-based insecticides have been effective against these little blighters, but evolution is quickly building up their resistance to this and other control measures. Fighting them with poison might be effective in the short term, but in the long run it only makes them stronger.

There is, however, a potential solution that can hijack the mosquito’s breeding cycle to dramatically bring down the population and human risk factors. And it’s undergoing testing in two very different ways right now.

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