About This Project

Exotic Haemaphysalis longicornis tick infestations have been detected in nine U.S states. In east Asia, this tick is thought to be a vector of multiple human and livestock pathogens. Current surveillance efforts focus on testing for these known pathogens using DNA probes, yet may fail to characterize unknown or evolving microbes. This project will use shotgun metagenome sequencing to describe the total microbiome of U.S H. longicornis populations in a next-generation pathogen screening approach.

Ask the Scientists

What is the context of this research?

In 2017, an infestation of exotic Haemaphysalis longicornis ticks was discovered in New Jersey (1) and subsequently nine primarily eastern U.S states. In east Asia, this tick is thought to be a vector of Oriental spotted fever, caused by the bacteria Rickettsia japonica (2) as well as a virus causing Severe Fever with Thrombocytopenia Syndrome (SFTSV) (3). Field-collected H. longicornis have been found to carry a range of bacteria and protozoa, including Borrelia, Bartonella, Anaplasma, Babesia, and Ehrlichia spp., although it is unknown if they are able to transmit these pathogens (4,5,6). In New Zealand it is a severe pest of cattle and transmits the agent of cattle theileriosis (7). The microbial diversity, including potential pathogens, that accompanied this tick to the U.S is unknown.

What is the significance of this project?

Current pathogen surveillance efforts regarding the invasive H. longicornis tick in the United States have focused on quantitative PCR-based assays using molecular probes. These probes are designed using consensus gene/genome sequence data from native-host-range viruses and bacteria. Although this method will qualify the presence of the particular pathogen being tested for, it will not detect evolved, emerging or unknown microorganisms of potential public health importance. Here we propose to use next-generation shotgun metagenome sequencing to assemble and classify the total microbiome of U.S H. longicornis populations. This approach will identify both known and unknown microbiota including RNA/DNA viruses, bacteria and protozoan parasites that accompanied the tick on its journey.

What are the goals of the project?

Final project deliverables will include a list of all viruses, bacteria and protozoan strains recovered in our U.S H. longicornis populations, along with functional genomic data in the form of metagenomic DNA/RNA scaffolds that can additionally be used to assess potential pathogenicity. To achieve this, we will sample three tick populations via collaborators in NJ, VA and AR. We will isolate, amplify and construct six Illumina metagenome sequencing libraries ([1 RNA / 1 DNA] x 3 sites) from total RNA and DNA fractions, and sequence these libraries on a MiSeq genome sequencer. Genome data will be annotated and taxonomically classified informatically via homology search algorithms to national gene and protein databases using the Rutgers Caliburn supercomputing infrastructure.