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Extracellular vesicles are thought to facilitate pathogen transmission from arthropods to humans and other animals. Here, we reveal that pathogen spreading from arthropods to the mammalian host is multifaceted. Extracellular vesicles from Ixodes scapularis enable tick feeding and promote infection of the mildly virulent rickettsial agent Anaplasma phagocytophilum through the SNARE proteins Vamp33 and Synaptobrevin 2 and dendritic epidermal T cells. However, extracellular vesicles from the tick Dermacentor andersoni mitigate microbial spreading caused by the lethal pathogen Francisella tularensis. Collectively, we establish that tick extracellular vesicles foster distinct outcomes of bacterial infection and assist in vector feeding by acting on skin immunity. Thus, the biology of arthropods should be taken into consideration when developing strategies to control vector-borne diseases. Extracellular vesicles have been implicated in the transmission of pathogens from the arthropod to the human host. Here the authors show that tick-derived extracellular vesicles play a role in feeding and modulate the outcome of bacterial infection. [ABSTRACT FROM AUTHOR]

Ticks transmit infectious agents to humans and other animals. Genetic manipulation of vectors like ticks could enhance the development of alternative disease control strategies. Transgene expression using the phytopathogen Agrobacterium tumefaciens has been shown to promote the genetic modification of non-plant cells. In the present work we developed T-DNA constructs for A. tumefaciens to mediate transgene expression in HeLa cells as well as Rhipicephalus microplus tick cells. Translational fusions eGfp: eGfp or Salp15: eGfp, including the enhanced-green fluorescent protein and the Ixodes scapularis salivary factor SALP15 genes, were constructed using the CaMV 35S (cauliflower mosaic virus) promoter, 'PBm' tick promoter ( R. microplus pyrethroid metabolizing esterase gene) or the Simian Virus SV40 promoter. Confocal microscopy, RT-PCR and Western-blot assays demonstrated transgene(s) expression in both cell lines. Transgene expression was also achieved in vivo, in both R. microplus and I. scapularis larvae utilizing a soaking method including the A. tumefaciens donor cells and confirmed by nested-RT-PCR showing eGfp or Salp15 poly-A-mRNA(s). This strategy opens up a new avenue to express exogenous genes in ticks and represents a potential breakthrough for the study of tick-host pathophysiology. [ABSTRACT FROM AUTHOR]

As it feeds upon cattle, Rhipicephalus ( Boophilus) microplus is capable of transmitting a number of pathogenic organisms, including the apicomplexan hemoparasite Babesia bovis, a causative agent of bovine babesiosis. The R. microplus female gut transcriptome was studied for two cohorts: adult females feeding on a bovine host infected with B. bovis and adult females feeding on an uninfected bovine. RNA was purified and used to generate a subtracted cDNA library from B. bovis-infected female gut, and 4,077 expressed sequence tags (ESTs) were sequenced. Gene expression was also measured by a microarray designed from the publicly available R. microplus gene index: BmiGI Version 2. We compared gene expression in the tick gut from females feeding upon an uninfected bovine to gene expression in tick gut from females feeding upon a splenectomized bovine infected with B. bovis. Thirty-three ESTs represented on the microarray were expressed at a higher level in female gut samples from the ticks feeding upon a B. bovis-infected calf compared to expression levels in female gut samples from ticks feeding on an uninfected calf. Forty-three transcripts were expressed at a lower level in the ticks feeding upon B. bovis-infected female guts compared with expression in female gut samples from ticks feeding on the uninfected calf. These array data were used as initial characterization of gene expression associated with the infection of R. microplus by B. bovis. [ABSTRACT FROM AUTHOR]