Development of a taqman real-time PCR for the identification of haemaphysalis longicornis (Acari: ixodidae)

Authors: XU, GUANG - University Of Massachusetts; RIBBE, FUMIKO - University Of Massachusetts; MCCAFFERY, JOSEPH - University Of Massachusetts; LUO, CHU-YUAN - University Of Massachusetts; Li, Andrew; RICH, STEPHEN - University Of Massachusetts

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2022
Publication Date: 5/28/2022
Citation: Xu, G., Ribbe, F., Mccaffery, J., Luo, C., Li, A.Y., Rich, S. 2022. Development of a taqman real-time PCR for the identification of haemaphysalis longicornis (Acari: ixodidae). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjac074.
DOI: https://doi.org/10.1093/jme/tjac074

Interpretive Summary: The Asian longhorned tick (Haemaphysalis longicornis) is an important tick species that is native to eastern Asia. This vector tick species can transmit approximately 30 human and animal pathogens. The introductions of this pest and disease vector to Australia from Japan in the nineteenth century, and later to New Zealand and several Pacific islands, have caused severe economic damages to dairy and wool productions in the region. Since its first discovery in New Jersey, this invasive species has been reported in 16 states in the United States by September 2021. Due to the small size and often damaged tick specimen, it has been challenging to identify this invasive tick species using morphological features. The USDA scientists collaborated with university researchers in developing a novel molecular assay for accurate and rapid identification of this tick species. The application of this Real-time PCR assay has led to the discovery of archived specimen of this invasive tick species that was collected 2 years prior to its first reported collection in 2017. This rapid molecular tick identification tool can be readily adopted by tick researchers, tick-borne disease epidemiologists, and public health agencies to facilitate surveillance work in order to monitor the spreading of this invasive tick species in the United States.

Technical Abstract: Haemaphysalis longicornis, a vector of various pathogens with medical and veterinary importance, is a recent invasive species in the United States. Like many tick species, discerning H. longicornis from congeners can be a challenge. To overcome the difficulty of morphological identification, a quantitative real time PCR based on the internal transcribed spacer gene (ITS2) was developed for quick and accurate identification of H. longicornis with a detection limit of as low as 19.8 copies. We also applied the assay to 76,004 archived ticks and found 37 ticks were H. longicornis. One H. longicornis was submitted from Warren, Somerset County, New Jersey in June 2015, two years earlier than the previous report. None of these 37 H. longicornis was positive for Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, B. miyamotoi, B. mayonii, Babesia microti or Ehrlichia muris–like agent.