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K-State Today

May 4, 2017



Division of Biology presents Kathryn Reif May 5

By Division of Biology

K. Reif

The Division of Biology will host Kathryn Reif at 4 p.m. May 5 in 221 Ackert Hall. Reif will present "Identifying Determinants of Vector Competence for Tick Borne Pathogens."

Reif will cover tick-borne diseases that are the most common vector-borne diseases of humans in the U.S. with the number of reported cases steadily increasing and the distribution of tick vector species and tick-borne pathogens continuing to expand and overlap. In the U.S., the number of reported tick-borne disease cases increased from about 17,000 cases in 2001 to more than 40,000 cases in 2014. Moreover, the number of reported tick-borne disease cases are believed to only represent 5-10 percent of actual annual cases, making the number of tick-borne disease cases in the U.S. more than 400,000 per year. Reasons for the increased number of tick-borne disease cases include expansion of tick geographic ranges, broadening of tick-borne disease endemic regions, over abundant deer populations, climate changes, and improved diagnostics and surveillance.

Vector competence describes the ability of the vector to transmit a pathogen. Some tick species, such as Ixodes scapularis and Dermacentor andersoni, can serve as competent vectors for numerous tick-borne pathogens. Additionally, some tick-borne pathogens can be successfully transmitted by multiple tick species. Vector competence for a given tick-borne pathogen can vary among tick species and among populations of a tick species recognized as a competent vector. Moreover, vector competence can be influenced by numerous biotic and abiotic variables. Examples of biotic variables that can affect vector competence include appropriate host cellular receptor for tick-borne pathogen attachment and entry; accessibility to required nutrients; and, direct or indirect interaction with other co-infecting microbiota. Examples of abiotic variables that can affect vector competence, and more broadly vectorial capacity, include temperature and humidity.

Reif will focus on microbial interactions, both interspecific and intraspecific interactions among microbes can specifically affect vector competence and influence transmissibility. Genetic diversity is a hallmark of vector-borne pathogens and studies across numerous systems have demonstrated that even for a single pathogen species, mixed-genotype infections are more common than infections with a single clonal variant. The capacity of hosts to sustain multiple pathogen genotypes, and the within-host interactions among co-infecting genotypes, can impact pathogen transmission, virulence, and immune evasion. However, for pathogens that cycle among multiple host species, especially vector-borne pathogens that cycle between disparate species — mammals and arthropods — the impact of genotypic diversity and genotypic interactions on individual genotype transmission and infection success is largely unknown. We use a set of differentiable Francisella novicida transposon mutants and Dermacentor andersoni ticks, which are a natural vector of Francisella sp. as a platform to study how pathogen genotypic diversity and interactions among genotypes affect colonization of the vector and resulting pathogen transmission.

If you would like to visit with Reif, please contact her at kreif@vet.k-state.edu.