120 YEARS OF ADVANCES FOR MILITARY AND PUBLIC HEALTH
The RV144 trial tested the “prime-boost” combination of two vaccines: ALVAC®-HIV vaccine (the prime) and AIDSVAX® B/E vaccine (the boost). MHRP photo
and encephalitis; and other arthropods – WRAIR investigators study them both in the field and in a global network of insectaries, anchored by WRAIR’s 964-square-foot facility in Maryland. The facility, which opened its doors – multiple, mosquito-proof doors – in 2000, is the starting point for all of WRAIR’s repellent, drug, and vaccine research for vector-borne diseases. The Anopheles mosquitoes used in WRAIR’s malaria challenge studies are bred, hatched, raised, and fed a blood meal with the Plasmodium parasite in the insectary. The products most often associated with the Entomology Branch are those that reduce the risk of being bitten by a carrier – either personal protective measures, such as topical repellents, treated uniforms, and bed nets, or vector controls such as pesticides. Topical repellents are too expensive for many people who live in the most mosquito-infested parts of the world, and the most effective one developed to date, DEET, has fallen out of favor among U.S. Service Members, for various reasons. Out of necessity, WRAIR’s entomologists spend time studying whether people are willing to use a repellent or not – and increasingly, they don’t like DEET. “It’s sticky and it eats plastics,” said Cmdr. Dan Szumlas, director of the Entomology Branch. “Nothing works like topical repellents, but if people don’t want to use them, then obviously they’re not effective at all. So we’re looking at different kinds of spatial repellents, or insecticides, that have that effect that people can use either on their uniforms, or on a device on their body, or in a device you can put in the middle of a group, and protect everyone from bites.” Branch investigators are developing a new generation of both topical repellents – such as picaridin, which is now available to troops – and spatial repellents.
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The Entomology Branch also conducts basic research into vector and parasite biology, and its field workers assist in worldwide vector surveillance efforts. Increasingly, given the enormity of such a task, this work is performed jointly, in partnership with several agencies, including the U.S. Department of Agriculture, the Naval Medical Research Center – which maintains several laboratories of its own – and the WRAIR’s own Walter Reed Biosystematics Unit (WRBU) headquartered at the Smithsonian Institution’s branch in Suitland, Md. Together, investigators from these institutions are participating in the Mosquito Barcoding Initiative (MBI), led by Dr. Yvonne-Marie Linton, a senior National Research Council fellow on assignment from the Natural History Museum in London. The MBI represents the first time researchers have collaborated in such a global effort against mosquito-borne diseases. Investigators are creating genetic references to the world’s mosquitoes by collecting specimens in the field or using museum specimens, identifying them to species, and finally sequencing “barcodes” that correlate with specific genes. One of the project’s ultimate goals is to equip field personnel with devices that can identify not only the mosquito species, but what kind of pathogen it might be carrying. Szumlas pointed out that aside from the obvious benefit to public health, this biosurveillance tool could help protect Soldiers deployed overseas. “In the field, the commander has so many things to worry about,” he said. “Infected bugs infecting people is one of those, but it’s probably a lower priority until the red flag goes up. And that’s what the surveillance is all about: To collect mosquitoes, identify what they are, and then see what’s in them. If there is malaria about to be transmitted, the commander of that unit can say to everyone, ‘If you have not been using your repellent, your prophylactics, your netting, you’d better right now, because we’ve got some hot mosquitoes out and around.’” Ironically, WRAIR’s entomologists, who continue to spend much of their energy trying to repel these insects, are working on better ways of attracting them – not only to participate in biosurveillance efforts, said Szumlas, but also to provide subjects for vector and parasite studies. “A lot of times,” he said, “they have been reared for so many years they’re not a wild type anymore, and they actually react very differently.” To lure mosquitoes, either in the laboratory setting or from within the huge screen tents erected in the field, WRAIR entomologists are evaluating a new generation of traps: some baited with sugar, which mosquitoes seek when they’re not looking for blood, and some with carbon dioxide, the signature attractant in the respiration of all warm-blooded animals.
THE MILITARY HIV RESEARCH PROGRAM When the United States launched its HIV/AIDS (Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome) research program in the 1980s, the Department of Defense, recognizing the threat the disease posed to end strength and readiness, had already begun developing protective measures – education programs, vaccine development, and innovative anti-viral therapies. In 1986, based on data collected at the Walter Reed Army Medical Center, the military program published evidence of the possibility – which was then a controversial idea – that HIV could be transmitted heterosexually. That same year, the Army also adopted the Walter Reed staging classification
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