Our research focuses on the genetics, ecology, evolution and pathogenesis of arthropod-borne viruses (arboviruses), virus-mosquito interactions and vaccine development. I currently have 5 major research projects funded by NIH grants:
1. Venezuelan equine encephalitis virus (VEEV) is responsible for several recent human and equine outbreaks in northern South America and Mexico. We have shown that epidemic VEEV strains evolved very recently from avirulent, enzootic viruses that circulate in sylvatic foci involving rodent hosts and mosquito vectors. We are using ecological studies, laboratory transmission experiments, and reverse genetic approaches to study VEE emergence at the molecular, ecological and geographic levels. The latter approach relies on satellite imagery to map the locations of enzootic VEE viruses with emergence potential. This project involves collaborations with scientists in Venezuela, Colombia and Mexico, and at the USDA.
2. We use similar approaches to study retrospectively the emergence of urban dengue viruses from zoonotic progenitors that use non-human primate reservoir hosts and sylvatic mosquito vectors. This project involves a collaboration with scientists at the Institut Pasteur in Senegal. Susceptibility studies have demonstrated that emergence of urban dengue was medicated by adaptation to peridomestic vectors, and the genetic determinants of this adaptation are now being identified.
3. We are also examining the effect of deforestation on arboviral diseases in the Amazon basin of Peru. Humans are now an important component of Amazonian ecological systems, and we hypothesize that anthropogenic disturbances alter the frequency of contact among reservoir hosts, vectors and viruses, changing transmission cycles and promoting epidemic emergence. Ecologic and laboratory studies are being used to test 3 hypotheses: (1) deforestation alters the enzootic transmission ecology, as vectors, reservoir hosts or viruses differentially respond or adapt to anthropogenic changes; (2) deforestation results in increased exposure of humans to arboviruses through ecotone elongation and peridomestic virus circulation; (3) arboviruses can adapt to introduced, peridomestic mosquito vectors and human hosts to colonize tropical cities, with devastating public health consequences. This project involves collaborations with mosquito and mammal ecologists at the University of Florida, Texas Tech University and the U.S. Naval Medical Research Center Detachment in Peru.
4. Because the vectors of most neotropical arboviruses belong to a subgenus [Culex (Melanoconion)] with poorly developed taxonomy and systematics, we are studying this group using molecular phylogenetics to develop a natural classification and genetic diagnostic tools. This project is a collaboration with Dr. Juan Carlos Navarro the Central University of Venezuela.
5. We are also developing new chimeric vaccines against VEEV, as well as eastern and western equine encephalitis viruses. Based on the Sindbis virus backbone and encephalitic alphavirus structural proteins, these chimeric viruses are useful as diagnostic reagents to improve laboratory safety. This project involves collaborations with Drs. Ilya Frolov, Slobodan Paessler and Judy Aronson at UTMB, Hans Heider at U. T. San Antonio, and William Klimstra and Kate Ryman at the LSU Medical Center.
Tel: (409) 266-6500
Fax: (409) 266-0610
Campus Location: 6.200D Galveston National Laboratory
Mail Route: 0610