Diversity of Viruses in Ixodes ricinus in Europe including Novel and Potential Arboviruses

Abstract

Tick-borne pathogens are responsible for many vector-borne diseases in Europe, causing important problems for human and animal health. The composition of viral communities in ticks and their interactions with pathogens is little understood, especially in Eastern Europe, an area that represents a major hub for animal-arthropod vectors exchanges. In this study, we used metatranscriptomics to characterize the virome of 2,753 Ixodes ricinus ticks collected from France and Romania, focusing on viruses that could potentially have implications for human or animal health. Among the great viral diversity of viruses identified, we reported a novel strain of Tribec virus, an important human pathogen that was found in Romanian ticks. We detected viruses belonging to the Phenuiviridae and Nairoviridae families close to human and animal pathogens, suggesting that these viruses could constitute novel arboviruses. We used luciferase immunoprecipitation system targeting external viral proteins of viruses identified among the Sedoreoviridae, Phenuiviridae, and Nairoviridae families to screen serum samples from small ruminants’ exposed to tick bites. The results suggest that part (approximately 12%, 95% CI 9.1–16.2) of the small ruminant population from Danube Delta, was exposed to viruses related to bi- or tri-segmented nairoviruses, but cross-reactive viruses could not be confirmed with certainly. The strategy developed in this study serves as a key step in predicting potential new disease outbreaks and can be readily adapted to study other reservoirs, vectors, and interfaces involving susceptible hosts.

Pathogens Detected in Questing Ixodes ricinus Ticks in a Mountainous Area in Greece

“…The virus, named Norway phlebovirus 1, was detected in all six libraries and clustered together with Blacklegged tick phlebovirus 1 [ 23 ]. Similar viruses have also been detected in Belgium, France, and Bulgaria [ 45 , 46 , 47 ].…”

“…Based on negative serological and cultural results, the authors suggested that the virus is associated with the virome of I. ricinus [24]. A similar virus was detected in France [47]. It is of interest that the closely related Yezo virus identified in 2021 in Japan is associated with febrile illness in humans [48].…”

“…The second nairovirus, the Grotenhout virus, was identified in 2009 through the next-generation sequencing of a pool of adult I. ricinus ticks in Belgium [ 25 ]. Similar viruses (with various names) are also present in several European countries [ 23 , 47 , 49 ]. As above, the closely related Beiji virus identified in China is associated with febrile illness in humans [ 50 ].…”