Research & Science

CORaV (genus Emaravirus, family Fimoviridae) is a single stranded RNA virus with a negative orientation (Rehanek et al. 2022). It´s genome consists of five RNAs (Rehanek et al. 2021) and phylogenetic analyses of RNA1-RNA4 confirm that the virus is a member of the genus Emaravirus (Rehanek et al. 2021). Studies on morphology of the virus are missing, although it is likely that CORaV forms spherical particles of varying size (80-100 nm) in the cytoplasm of infected mesophyll cells as described for other emaraviruses (Rehanek et al. 2022). Also, many epidemiological questions regarding the disease are still open, because the virus has only recently been identified as putative causal agent. For instance, investigations on the natural gall mite vector species of CORaV could not associate any mite species inducing galls on Quercus spp. with the ringspot disease, so far (Büttner et al. 2023). However, we could detect CORaV by RT-PCR in single free-living eriophyid mites of an unknown species collected from the underside of leaves showing typical leaf symptoms of the ringspot disease. The leaves were also confirmed to be CORaV-infected by virus-specific RT-PCR targeting the viral RNA3. Also the natural host range of the virus requires further research as similar symptoms have been described to occur for instance in Q. marilandica and Q. velutina, respectively in the USA (Cooper 1979), however, the virus is not yet confirmed as causal agent.