Evidence of Human Exposure to Tamdy Virus, Northwest China.

We report the isolation of Tamdy virus from Hyalomma asiaticum ticks in northwest China and serologic evidence of human Tamdy virus infection in the same region. These findings highlight the need to further investigate a potential causal relationship between Tamdy virus and febrile illnesses of unknown etiology in that region.

Tamdy Virus in Ixodid Ticks Infesting Bactrian Camels, Xinjiang, China, 2018.

We isolated Tamdy virus (TAMV; strain XJ01/TAMV/China/2018) from Hyalomma asiaticum ticks infesting Bactrian camels in Xinjiang, China, in 2018. The genome of the strain showed high nucleotide similarity with previously described TAMV strains from Asia. Our study highlights the potential threat of TAMV to public health in China.

Epidemiological surveys revealed the risk of TAMV spill-over from ticks to hosts.

BACKGROUND: Tick-borne viral diseases have become an increasingly important public health concern. Tamdy virus (TAMV) is a tick-borne virus of the genus Orthonairovirus in the family Nairoviridae. While some studies have suggested that TAMV is a pathogen associated with human febrile illness, its epidemiology and the risk of TAMV spill-over remain poorly understood. METHODS: Ticks were collected in Xinjiang, China, and grouped into pools. RT-PCR assays were used to detect TAMV RNA in these pools. The seroprevalence of TAMV was investigated using Immunofluorescence assays, Western blotting, and Luciferase immunoprecipitation system (LIPS) assays. RESULTS: TAMV RNA was detected in 17 out of 363 tick pools, resulting in a minimum infection rate (MIR) of 4.7%. Hyalomma asiaticum and Dermacentor nuttalli were identified as major tick vectors of TAMV. Phylogenetic analysis demonstrated that TAMV strains from Xinjiang are closely related to strains from other countries. Seroprevalence studies showed that TAMV exposure has been occurring in Xinjiang since at least 2006. Antibody responses to TAMV were detected in 1.1% (26/2296) of animals, including domestic animals and wild rodents. The seropositivity rates were as follows: sheep (1.7%), dog (2.3%), Marmota monax (0.8%), Meriones meridianus (3.5%). CONCLUSIONS: The research findings reveal that TAMV can be transmitted by ticks to various animal species, posing a significant public health risk. The wide distribution of TAMV and its tick vectors emphasise the importance of early preparedness and control measures. This study highlights the necessity for maintaining vigilance in addressing emerging zoonotic diseases transmitted by ticks.

Serological Evidence of Bactrian Camel Infection with Tamdy Virus, Xinjiang, China.

Background: Tamdy Virus (TAMV) is a pathogenic nairovirus widely distributed in central Asia and northwestern China. However, the host range of TAMV remains unclear, which limits our understanding the transmission cycle and cross-species patterns of this virus. Materials and Methods: A total of 160 serum samples were collected from livestock animals of camels, cattle, and sheep in Xinjiang, China between 2018 and 2021. An indirect immunofluorescence assay for TAMV were developed in this study, and have been employed to test TAMV-specific antibodies in these serum samples. Results: TAMV IgG antibody was detectable in camel sera collected from Urumqi in 2018 (6/17, 35%) and also from the Alertai Region in 2021 (1/8, 12.5%). Conclusion: The serological results in this study provide the first evidence that TAMV is able to infect camels and that the pathogen is circulating in different regions of Xinjiang. These findings highlight the need to further increase clinical and epidemiological surveillance of TAMV in humans and livestock in northwestern China.

Rapid detection of the emerging tick-borne Tamdy virus by TaqMan-based real-time reverse transcription PCR.

Tamdy virus (TAMV) is an emerging zoonotic tick-borne arbovirus in the genus Orthonairovirus. Reports of human infections with TAMV have been increasing and development of a rapid detection assay is thus urgently required. In the present study, singleplex and dual-target real-time reverse transcription PCR (qRT-PCR) assays were established for the detection of TAMV. Sensitivity and specificity were evaluated, which demonstrated high sensitivity for both the singleplex and dual-target qRT-PCR assays with no cross-reaction with common bunyaviruses and tick-borne viruses. The TaqMan-based qRT-PCR methodology established in this study can be employed for epidemiological surveillance and pathogenesis studies of TAMV.

Multiple orthonairoviruses including Crimean-Congo hemorrhagic fever virus, Tamdy virus and the novel Meram virus in Anatolia.

We conducted orthonairovirus RNA screening of 7043 tick specimens-representing 16 species-collected from various regions of Anatolia. In 602 pools, Crimean-Congo hemorrhagic fever virus (CCHFV) Europe 1 and 2 lineages were detected in seven pools (1.1 %) comprising Hyalomma marginatum, Hyalomma scupense, Rhipicephalus bursa, Rhipicephalus sanguineus sensu lato and Rhipicephalus turanicus ticks. In pools of Hyalomma aegyptium, we detected Tamdy virus (TAMV) and an unclassified nairovirus sequence. Next-generation sequencing revealed complete coding regions of three CCHFV Europe 2 (AP92-like) viruses, TAMV and the novel orthonairovirus, tentatively named herein as Meram virus. We further performed in silico functional analysis of all available CCHFV Europe 2, TAMV, Meram and related virus genomes. The CCHFV Europe 2 viruses possessed several conserved motifs, including those with OTU-like cysteine protease activity. Probable recombinations were identified in L genome segments of CCHFV and TAMV. Through phylogeny reconstruction using individual genome segments, Meram virus emerged as a distinct virus among species within the Orthonairovirus genus. It further exhibited conserved motifs associated with RNA binding, encapsidation, signal peptidase cleavage, post-translational modification, RNA-dependent RNA polymerase and OTU-like activities. Bole tick virus 3 was also detected in two pools with CCHFV reactivity. Hereby, we describe a novel tick-associated orthonairovirus, in a CCHFV-endemic region with confirmed TAMV activity. Human and animal health impact of these viruses need to be addressed.