Detection of HFRSV in Eulaelaps shanghaiensis and Ornithonyssus bacoti by using in situ hybridization

AIM: To provide molecular biological evidence of transmission of hemorrhogic fever with renal syndrome virus (HFRSV) by gamasid mites, Eulaelaps shanghaiensis and Ornithonyssus bacoti. METHODS: Frozen sections of the gamasid mites 10 days and more than 100 days after biting suckling mice inoculated with HFRSV were in situ hybridized with dig-labelled HFRSV cDNA probes. RESULTS: RNA was detected in frozen sections of Eulaelaps shanghaiensis, after biting suckling mice inoculated with Hantaan (76-118) and Seoul (UR) virus, respectively. Most of the fine granules of the virus RNA were located in the nuclei, cytoplasm and nuclear membrane of cells of brain cortex, caeca and genitalia of the mites. In situ hybridization results showed that 17 of 31 mites in Hantaan group and 10 of 23 mites in Seoul group were positive. The virus RNA was still detected in tissues of the mites on d132 for Hantaan group and on d102 for Seoul group after infection, respectively. Among 20 Ornithonyssus bacoti detected 12 were positive on d10 after biting suckling mice inoculated with Hantaan virus, and the virus RNA was mainly found in the cells of genitalia (Figs. 1-13). CONCLUSION: Both Eulaelaps shanghaiensis and Ornithonyssus bacoti could be infected with HFRSV by biting HFRSV-positive mice. E. shanghaiensis could be infected with both Hantaan and Seoul virus, and the two types of HFRSV were found to be maintained in the mites for 132 days and 102 days, respectively. These confirmed that E. shanghaiensis and O. bacoti are suitable vectors and reservoirs of both Hantaan and Seoul virus and might play an important role in the cross transmission of the two types of HFRSV.