Hamer Receives $3.5 Million to Study Mosquito-Borne Viruses

Lopa Chakraborty checking a trap

Technician Lopa Chakraborty collecting mosquitoes from an Autocidal Gravid Ovitrap in the Lower Rio Grande Valley of South Texas. Photo by Ester Carbajal.

Mosquitoes are considered the deadliest animal on the earth, not because of the annoying bite, but because of their ability to transmit pathogens resulting in human diseases such as Malaria, West Nile and Dengue fever, and most recently, Zika.

Assistant Professor of Entomology, Dr. Gabriel Hamer, has received $3.5 million in new funds in the past year from several agencies to research mosquitoes and mosquito-borne viruses.  According to Hamer, “These applications for external support were prepared by large collaborative teams from multiple universities and agencies”.

Two of these awards are from the National Institutes of Health (NIH) with one being a career development award (K01) titled “Consequences of pathogen co-infection in mosquitoes on West Nile virus transmission.” The grant, Hamer said, would provide protected time to enhance his lab’s capacity in the fields of virology, mathematical modeling, and to conduct laboratory transmission experiments.  These skills will be enhanced while conducting laboratory mosquito co-infection experiments of both avian malaria and insect-specific viruses with West Nile to see how co-circulating pathogens in nature influence the way which mosquitoes transmit West Nile Virus.  “The project aims to understand the mechanisms of how this virus amplifies so successfully in the mosquito-bird cycle in the U.S. which then results in spill-over transmission to humans and animals,” Hamer said. “The better we understand this process, the more effective we will be at predicting when the risk of transmission is highest and how to efficiently intervene to block transmission using control measures.”  The mentor team for this award includes Dr. Sanjay Reddy, Texas A&M University, Dr. Scott Weaver, University of Texas Medical Branch, and Dr. Renata Ivanek, Cornell University.

Members of Dr. Gabe Hamer’s lab working with the community to sample mosquito larvae from container habitat in South Texas. Photo by Ester Carbajal.

Members of Dr. Gabe Hamer’s lab working with the community to sample mosquito larvae from container habitat in South Texas. Photo by Ester Carbajal.

A second award from the NIH is an R21 titled “Social-ecological factors influencing receptivity to Zika virus and the efficacy of interventions in communities along the Texas-Mexico border.”  Hamer said this project will evaluate a mosquito control technique using the Autocidal Gravid Ovitrap.  This trap, developed by researchers at the Centers for Disease Control, is a simple five gallon bucket attracting mosquitoes with water but instead of reaching the water to lay eggs, the female mosquito gets stuck to a sticky surface and dies.  Once this trap is deployed in large numbers, it has proven to be an effective tool in Puerto Rico so Hamer and colleagues will explore the potential for this trap to be used in an integrative approach to control mosquitoes in Texas.

Hamer also has two awards from the Centers for Disease Control and Prevention (CDC).  The newest is titled “Dispersal, larval habitat source, and efficacy of intervention using autodissemination on Aedes aegypti and Aedes albopictus in South Texas”.  The objectives, Hamer said, are to identify the relative importance of different container habitats for producing Aedes aegypti and Aedes albopictus mosquitoes and understanding how far adult mosquitoes travel from these water habitats.  In addition, this project will evaluate the ability of autodissemination stations to control mosquitoes.  These control tools work by attracting females to a simulated habitat where she will lay eggs but while doing that, she is comes into contact with the container side and is dusted with an insect growth regulator.  Then as this female travels to other natural larval habitat, she inadvertently treats those other habitats with this larvicide preventing the production of mosquitoes.

Hamer is also an investigator in the CDC-funded “Western Gulf Center of Excellence for Vector-Borne Diseases”.  The lead institution of this project is the University of Texas Medical Branch in Galveston, TX but several investigators from Texas A&M University are involved.  Hamer’s contributions will be to work with local agencies in the Lower Rio Grande Valley area to help improve their intervention strategies in controlling mosquitoes. Hamer’s team will use field data and mathematical modeling to help determine the necessary level of control needed to reduce mosquito populations below the threshold necessary to maintain mosquito-borne viruses such as Zika virus. In addition, Hamer and colleagues will study the social science dimensions of vector control by conducting public surveys of citizens in several communities in Texas to evaluate the impact of mosquitoes on their quality of life, their support or opposition to different mosquito control techniques, and their willingness to pay for mosquito control.

Hamer is also receiving funds from the Lawrence Livermore National Laboratory for a project titled “Integrated vector-animal-human test bed for surveillance of high-consequence transboundary infectious diseases”.  Hamer says this project aims to study the receptivity of South Texas communities for emerging mosquito-borne viruses as well as partnering with local agencies to conduct enhanced biosurveillance.  Mosquito samples are being collected and screened broadly for many viruses and other microbes both in Hamer’s lab in College Station and also at the National Lab in California.

Hamer also has a contract from the Department of Homeland Security titled “Competence of North American arthropod vectors for high consequence or transboundary foreign animal diseases”.  This collaborative project will conduct a quantitative synthesis of published studies to evaluable the risk of introduction and transmission of Rift Valley Fever virus, Japanese encephalitis virus, Venezuelan encephalitis virus, and African swine fever viruses, Heartwater (Ehrlichia ruminantium) to be transmitted in the continental U.S.

“The global pandemic of Zika virus has stimulated interest and funds to allow researchers to urgently address critical gaps in knowledge”, according to Hamer.  We are in a unique position in Texas given that we are at the front lines to Zika virus which is now established in Mexico and has resulted in 6 locally-acquired human cases in South Texas.

Several of these new projects based in in the Lower Rio Grande Valley are possible thanks to the support of the Texas A&M AgriLife Research and Extension Center at Weslaco.  “Dr. Juan Landivar (Center Director) and Dr. Ismael Badillo-Vargas (Assistant Professor) have been very supportive in helping to acquire these external grants and manage these projects”, Hamer says.  “One of the most exiting aspects of these new projects is the opportunity to grow our collaborative team with the addition of other investigators, post-doctoral researchers, and graduate students.  We have a lot of accomplish in the next few years”.

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