UC Irvine professor Dr. Alan G. Barbour and researchers Jianmin Zhong and Algimantas Jasinskas found that certain antibiotics reduced the number of bacteria in ticks, and this was associated with retarded growth in immature ticks and reduce reproduction by adult females.
"The significance is that control of ticks as vectors of disease and as pests for humans, pets and agricultural animals might be achieved by targeting inborn bacteria that the ticks depend on for achieving full growth and reproduction," Barbour said.
The yearlong study focused on the lone star tick, Amblyomma americanum, which is common in the southern and eastern United States and transmits erhlichiosis and other infections to humans and other animals. All of the ticks of this species have bacteria that appear to live symbiotically with the arthropod and are passed from one generation to the next. The bacteria are found at highest concentrations in nymphs that have not quite reached adulthood and in engorged females. Ticks were divided into three groups and injected either with the antibiotics rifampin or tetracycline, or with a buffer that contained no antibiotics. In the groups that got antibiotics, the nymphs gained less weight than control ticks, and the females took longer to lay eggs, hatched fewer eggs and produced fewer viable larvae.
Because the bacteria are only distantly related to humans and other vertebrates, compounds that selectively inhibit or kill the bacteria could be identified and taken as a supplement by at-risk animals as part of an integrated pest management program. The compounds would then be passed through the blood to feeding ticks. This may provide an improvement over current use of pesticides that target ticks directly but also may be toxic to vertebrates and beneficial insects.
Barbour, Zhong and Jasinskas conducted the research under the auspices of the Department of Microbiology and Molecular Genetics, Department of Medicine and the Pacific-Southwest Center for Biodefense and Emerging Infections at UCI. Zhong also is affiliated with the Department of Biological Sciences at California State University Humboldt.
uci
The Iowa Center for Research on Botanical Dietary Supplements brings together plant scientists, biochemists, nutritionists, chemists, immunologists, food scientists, virologists, metabolic scientists and statisticians. Center strengths include genomic analysis, broad-based plant metabolic profiling and an ability to integrate complex datasets by using bioinformatics and other statistical tools, Birt said. "One particular strength we have is our ability to control the genetics and growth conditions of the plant material used in our cellular and animal model studies," Birt said. "Being able to characterize known-source germplasm is a very important resource for our center."
In the renewal, researchers will continue to conduct the anti-viral, anti inflammatory and pain receptor studies to see how components can block inflammation by stimulating the receptor to down regulate it.
"In the next three years, we'll include emphasis on bioavailability," Birt said. "We don't know if the chemicals we've identified are absorbed. We'll also be looking at the mechanism, focusing on cellular, signaling, pathways and receptors."
And they will add a third plant, Prunella. Also known as self heal, Prunella has been used to treat ailments such as inflammatory bowel disease, fever, headache and diarrhea.
"Prunella grows well in Iowa. We have made some extracts and saw very good activity ”both antiviral and anti-inflammatory, so it fits well with what we're doing," Birt said.
The nine Iowa State faculty involved are from four colleges (Liberal Arts and Sciences, Agriculture, Human Sciences and Veterinary Medicine.) In addition, two scientists from the USDA Plant Introduction Center, two faculty from Yale and one from the University of Iowa conduct research for the center.
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