Those malaria mosquitoes may have met their match--with researchers at the University of California, Davis.

UC Davis entomology doctoral candidate Ashley Horton, recent winner of the 2010 Arthur J. and Dorothy D. Palm Agricultural Scholarship, focuses her research on how mosquitoes transmit malaria.

Horton studies with major professor Shirley Luckhart, professor in the Department of Medical Microbiology and Immunology and researches how the immune system of the malaria mosquito, Anopheles gambiae, affects the transmission of the Plasmodium parasite, the causative agent of malaria.

Malaria kills more than a million people a year, primarily in Africa.

“Ashley’s work that was recently published in Malaria Journal, together with our co-authors and collaborators Dr. Yoosook Lee and Dr. Gregory Lanzaro, is the first to identify mutations in immune signaling genes that exhibit associations with natural infection with Plasmodium falciparum in field-collected Anopheles gambiae mosquitoes in Mali," Luckhart said. "Plasmodium falciparum is the most important human malaria parasite in Africa and this work is necessary as a foundation to assess whether genetic control measures to block transmission of this parasite will be possible in malaria-endemic countries.”

The research, titled "Identification of Three Single Nucleotide Polymorphisms in Anopheles gambiae Immune Signaling Genes that are Associated with Natural Plasmodium falciparum Infection," appears in the June 10, 2010 edition of Malaria Journal.

Horton, who received her bachelor's degree in public health studies at The Johns Hopkins University, Baltimore, joined the UC Davis Entomology Graduate Program in 2005. In 2008 she received a William Hazeltine Student Research Fellowship, an award in memory of a noted California entomologist.

The Palm scholarship supplements her fellowship support from a National Institutes of Health T32 training grant that is managed by director Lanzaro and associate director Luckhart.

Arthur Palm, an alumnus of UC Davis, received his bachelor's degree in agricultural economics in 1939. He and his wife established the endowed fund to support undergraduate and graduate students.

The Palm family and others who fund scholarships not only support our university students; they support public health issues.

They, too, are tackling malaria.

It's exciting work, and he'll be at UC Davis to tell us about it.

Peter F. Billingsley (right), senior director of Entomology and Quality Systems at Sanaria Inc., Rockville, Md., will speak on "Development of a Mosquito-Derived, Attenuated Whole Parasite Vaccine against Malaria" on Friday, Dec. 3.

His talk--from 12:10 to 1 p.m. in the UC Davis Genome Center Auditorium, 1005 Genome and Biological Sciences Facility, 451 Health Sciences Drive--is part of the UC Davis Department of Medical Microbiology and Immunology Seminar Series, "Emerging Challenges in Microbiology and Immunology."  It's also affiliated with the UC Davis Department of Entomology fall seminar series.

Host is Shirley Luckhart, associate professor of medical microbiology and immunology, who studies the malaria mosquito, Anopheles gambiae. Luckhart's many roles include serving as a graduate student advisor in the Department of Entomology.

Sanaria? It's a self-described "biotechnology company dedicated to the production of a vaccine protective against malaria caused by the pathogen Plasmodium falciparum."

Billingsley has more than 20 years experience in medical entomology and malaria transmission research. He directed research teams at Imperial College, London, and the University of Aberdeen, Scotland, examining diverse aspects of insect biology related to disease transmission, especially midgut and salivary gland biology, and more recently the molecular physiology of aging in mosquitoes.

Billinglsey, who earned his doctorate at Queen’s University in Canada, is a former head (chair) of zoology in the School of Biological Sciences,  Aberdeen University.

Since 2006, he has devoted his broad expertise to the unique challenges of developing and deploying a live attenuated Plasmodium falciparum sporozoite vaccine at Sanaria Inc.

Billingsley's talk is generating a lot of interest, as well it should.

According to the Centers for Disease Control and Prevention (CDC), malaria kills more than a million people a year: "In 2008, an estimated 190 - 311 million cases of malaria occurred worldwide and 708,000 - 1,003,000 people died, most of them young children in sub-Saharan Africa."

A malaria-proof mosquito?

Research news coming out of the University of California, Davis and the University of Arizona labs recently drew international attention; the scientists have genetically engineered mosquitoes that are resistant to malaria parasites.

Now one of the co-authors has received a coveted research fellowship from the National Institutes of Health (NIH).

Entomology doctoral student Anna Drexler (top photo)
who studies with noted malaria researcher and major professor Shirley Luckhart (left), has received a NIH research fellowship aimed to promote diversity in health-related research.

Luckhart is an associate professor in the Department of Medical Microbiology and Immunology, UC Davis School of Medicine, and a graduate student advisor in the UC Davis Department of Entomology.

Drexler, who joined the Luckhart lab in January 2008, focuses her research on the roles of the human blood-derived insulin-like growth factor-1 and the role of insulin signaling in the regulation of malaria parasite transmission by Anopheles mosquitoes.

The UC Davis student is a co-first author of a paper on malaria parasites published July 15, 2010 in the journal Public Library of Science Pathogens (PLOS). Titled “Activation of Akt Signaling Reduces the Prevalence and Intensity of Malaria Parasite Infection and Lifespan in Anopheles stephensi Mosquitoes,” the work is a collaborative effort between UC Davis and the University of Arizona.

Co-authors include Luckhart and UC Davis researcher Ed Lewis, who has a joint appointment with the Department of Nematology and the Department of Entomology.

The paper, with more than 4200 article views in July alone, has drawn extensive news coverage. BBC science reporter Victoria Gill, in a July 16th article headlined “Malaria-Proof Mosquito Engineered,” wrote that the scientists “have succeeded in genetically engineering a malaria-resistant mosquito.”

In a July 17th piece, “Malaria-Proof Mosquito Created,” ABC News science writer Eric Bland wrote that scientists have created a malaria-proof mosquito by engineering "a genetic ‘on switch' that permanently activates a malaria-destroying response.”

“If these mosquitoes,” Bland wrote, “are successfully introduced into the wild, they could prevent millions of people from becoming infected with life-threatening Plasmodium--the parasite that causes malaria.”

Drexler, who grew up in Washington, D.C., received her bachelor’s degree in integrative biology, with an emphasis on animal biology, from UC Berkeley in 1999. She earned  her master’s degree in physiology and behavior from San Francisco State University in 2006.

The competitive NIH fellowships are available to provide funds to qualified students for stipends, research supplies, and research-related travel under an existing parent research grant.

The applications are evaluated on multiple criteria, including career goals, prior research training, research potential and relevant experience, and evidence of educational achievement.

This research is so important: targeting a killer that causes more than a million human deaths a year worldwide.

It's a killer, pure and simple.

But the issue is as complex as it comes.

The malaria mosquito, from the genus Anopheles, infects some 350 to 500 million people a year, killing more than a million. Most are young children in sub-Saharan Africa.

Female mosquitoes “bite” because they require a blood meal to develop their eggs. They detect their prey via olfactory receptor neurons found on their antennae, the insect equivalent to the human “nose.”

When Anopheline mosquitoes are infected with a parasite that causes malaria, the insect-host transmission occurs.  The result: a deadly killer.

Identifying exactly how malaria mosquitoes detect their human prey is crucial to developing strategies for mosquito control, says chemical ecologist Walter Leal, professor of entomology at the University of California, Davis.

Leal, recently asked to write a "News-and-Views" piece on a Yale-Vanderbilt study for the international science journal, Nature, did so eloquently in its March 4th edition. He praised the scientific report as a “milestone discovery in our understanding of the malaria mosquito’s sense of smell.”

In the article, headlined "The Treacherous Scent of a Human," Leal zeroes in the widespread threat of malaria, a disease that threatens half of the world’s population. It's "an accessory to the deaths of about one million humans every year,” Leal wrote. “Globally, the number of people who get malaria each year is greater than the population of the United States.”

That's putting a number on the numbers.

The Yale-Vanderbilt team, headed by John Carlson of the Yale Department of Molecular, Cellular and Developmental Biology, examined 79 of the malaria mosquito’s odorant receptors, finding that some are well-tuned to detect specific human odors and others aren’t. Certain odorants activate some receptors but inhibit others, according to their comprehensive study published March 4 in Nature.

Indeed. The Leal lab back in 2008 published groundbreaking research that revealed the secret mode of the insect repellent, DEET. The scent doesn't jam the insect senses and it doesn't mask the smell of the host, as scientists previously thought. Mosquitoes avoid it because it smells bad to them.

Leal advocates more molecular studies in the war against malaria and other mosquito-borne diseases. But that research can't stand alone. As he succinctly points out:  “The development of effective malaria control will require a multidisciplinary approach that includes, but is not limited to, improvements to social infrastructure in countries affected by disease, vaccination programs and vector management.”

New mosquito attractants or repellents, he says, could be developed through reverse chemical ecology, determining which odorant attracts and which repels.

Mosquitoes don't like the scent of DEET. What else do they NOT like?

The study, as Leal correctly observes, "offers a fresh strategy for controlling the unwitting accessories to one of the world’s most prolific killers.”