Abstract
Background: Ticks and fleas are important vectors and hosts for various emergent human pathogens, such as severe fever with thrombocytopenia syndrome virus, Crimean-Congo hemorrhagic fever virus, and tick-borne encephalitis virus. In the Qinghai-Tibet plateau of China, Marmota himalayana (marmots) serves as the primary reservoir for Yersinia pestis, primarily transmitted by fleas. Due to their wide distribution and large population, marmots serve as important host animals for ticks and fleas to survive and reproduce on the Qinghai-Tibet Plateau. However, the spectrum of RNA viruses found in ticks and fleas that feed on marmots is still not fully understood. Methods: Ticks and fleas infesting marmots in the Qinghai-Tibet plateau, China, were collected in 2018. The RNA virome of pooled ticks and fleas were analyzed using a metatranscriptomics approach. Results: A total of 30 RNA viruses were identified, with 11 viruses from ticks (Ixodes spp.) and 19 viruses from fleas (Oropsylla silantiewi), which were classified into 16 families, mainly Phasmaviridae (n = 4), Phenuiviridae (n = 4), and Iflaviridae (n = 3), Peribunyaviridae (n = 2). These viruses formed distinct clusters and shared less than 84% amino acid identity with their closest relatives, indicating that they belonged to novel members of their respective taxa and circulated among ticks and fleas for an extended period. Furthermore, six nearly identical viruses were shared between ticks and fleas, with 96.0 - 99.8% RNA-dependent RNA polymerase amino acid identity, but only 38.5 - 73.8% identity with known viruses, indicating potential interspecies transmission of viruses between ticks and fleas. Conclusion: Overall, these findings highlight the diverse and abundant viruses that arthropods in the Qinghai-Tibet plateau can harbor, shedding light on the potential for cross-species transmission of viruses.