Morphological and molecular identification of hyalomma tick vectors of crimean-congo hemorrhagic fever virus

Georgia Southern University Research & Service Foundation Inc. received a $710,000 Project Grant from the National Institute of Allergy and Infectious Diseases (NIAID) under the Allergy and Infectious Diseases Research program (CFDA 93.855), effective June 1, 2025, through May 31, 2028. The project delivers comprehensive morphological and molecular identification tools for Hyalomma tick species that vector Crimean-Congo Hemorrhagic Fever (CCHF) virus, which presents significant public health risks across Europe, Asia, and Africa with an estimated 30% human fatality rate.

The grant supports two primary deliverables: (1) resolving the systematics of closely related Hyalomma species responsible for CCHF virus transmission through morphological examination, diagnostic character illustration, and multivariate statistical analysis of museum specimens, and (2) developing molecular diagnostic tools using high-throughput genomic sequencing (Illumina short-read and Oxford Nanopore long-read sequencing) to enable accurate species identification at all life stages, including larvae and nymphs. These tools address critical gaps in vector surveillance and pathogen epidemiology by providing taxonomic keys and real-time PCR assays that facilitate precise species identification, essential for disease prevention and treatment strategies in endemic regions.

Abstract

Ticks are obligate blood-feeders, temporary ectoparasites, and vectors of pathogens to humans and animals. Certain species of the genus hyalomma are the principal vectors of the virus that causes crimean-congo hemorrhagic fever (cchf), which poses a health risk in large territories of europe, asia, and africa and fatal to an estimated 30% of affected humans. Hyalomma species are also important vectors of pathogens causing rickettsioses in humans and babesioses, anaplasmosis, and theileriosis in animals. The rationale for the proposed research is that correct identification of tick species, particularly in the immature stages, is essential for surveillance of vectors and pathogens, epidemiology, prevention, and treatment of tick-borne diseases. However, identifying major hyalomma species-vectors is challenging because the systematics of species within groups of closely related species remains unresolved. Additionally, identification of species in the larval and nymphal stages is almost impossible due to the lack of proper taxonomic works, identification keys, and molecular diagnostic tools (e.g. real-time PCR assays).the overall objective of the proposed project is to develop comprehensive tools (morphological and molecular) that effectively identify closely related hyalomma species that are vectors of cchf virus. This will be achieved through two specific aims: (1) resolve the systematics within groups of closely related species of hyalomma responsible for the transmission of cchf virus; such as h. Marginatum (5 SP.), h. Truncatum (3 SP.) and h. Anatolicum (2 SP.), through: 1A) using morphological data by examination of available specimens, illustration of diagnostic characters, and application of multivariate statistics; and 1B) using both high throughput illumina short read and oxford nanopore long read genomic data, guided assembly and annotation, and coalescence-based phylogenetic analyses. (2) to produce comprehensive morphological taxonomic keys and a molecular diagnostic tool for the identification of closely related hyalomma species-vectors of cchf virus at each parasitic stage by: 2A) constructing fully illustrated, web-based, interactive, multi-entry identification keys using morphological characters; and 2B) using the genomic sequence data from aim 1B to identify diagnostic gene or sequence regions for development of a multiplex taqman probe based real-time PCR assay for the accurate identification of closely related hyalomma species. The impact of this research program is that IT will develop effective identification tools for hyalomma species serving as major vectors of cchf virus, through the integration of genomic, morphological, host, and geographic information. These tools will be useful to healthcare providers and scientists in numerous fields, including epidemiology, vector biology, and tick-borne diseases. A PHD student and at least 6 undergraduates will be trained and instrumental in the completion of all aspects of the project strengthening their preparation for future education and careers in the biomedical fields, including vector biology, systematics, and zoonotic infectious diseases.