Detection of Transcripts and an Infectious Dose of Murine Gammaherpesvirus 68 in Dermacentor reticulatus Ticks

Background: Murine gammaherpesvirus 68 is assumed to be a natural pathogen of murid rodents. Previous investigations of MHV68 in field-collected Dermacentor reticulatus, Ixodes ricinus, and Haemaphysalis concinna ticks support the idea that ticks acquire the virus from feeding on infected hosts. Based on our previous finding of a live MHV-68 capable to replicate in mammalian cells, we aimed to investigate if transcripts of MHV-68 are present in D. reticulatus ticks and to determine the amount of MHV-68 in these ticks. Methods: This study utilized a sensitive nested RT-PCR method to detect transcripts of the early-late M3 gene of MHV-68, then nested PCR to screen MHV-68 presence and real-time PCR to quantify virus infectious dose in ticks. Results: Transcripts of MHV-68 M3 gene were detected in 10 out of 11 questing ticks. MHV-68 was detected in 38 out of 48 questing ticks, in which an infectious dose of MHV-68 varies from 2.2 × 104–8.6 × 106 copies of the virus genome. Conclusion: We report the first evidence of MHV-68 transcription and infectious dose of MHV-68 in field collected D. reticulatus ticks. Results provide unique evidence that ticks could act as a reservoir of gammaherpesvirus, which could be capable of replication.