Electrical Transport Properties of Topological Insulators

Abstract

Vector-borne diseases have a major impact in mortality and morbidity throughout the tropics. Vector-borne pathogens are transmitted to humans by blood feeding arthropods like mosquitoes and ticks. A true understanding of the vector-borne disease cycle requires the study of the major players involved in this cycle: the mammalian host, the pathogen and the arthropod vector. This thesis examines these aspects by using a tick-borne disease – human granulocytic anaplasmosis (HGA) – as a model. Chapters 1, 2 and 3 emphasize the importance of vector-borne diseases and discuss medically relevant arthropod vectors in light of their immune response to human pathogens. The etiologic agent of HGA, Anaplasma phagocytophilum, is also examined in detail, with a focus on immune evasion strategies used to colonize mammals and ticks. Chapters 4 thru 6 are dedicated to address pathogen, host and the tick vector, respectively. First, the contribution of one A. phagocytophilum gene – the dihydrolipoamide dehydrogenase – to infection is demonstrated. Next, the role of tick saliva as an immunomodulator of A. phagocytophilum infection in the mammalian host is revealed. Finally, an Ixodes scapularis X-linked inhibitor of apoptosis protein is described as an E3 ubiquitin ligase that controls tick colonization by A. phagocytophilum. In summary, this dissertation uncovers three distinct events underlying the tick-pathogen-host interface.