Detection and identification of putative bacterial endosymbionts and endogenous viruses in tick cell lines

M. P. Alberdi, M. J. Dalby, J. Rodriguez-Andres, J. K. Fazakerley, A. Kohl, Lesley Bell-Sakyi

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As well as being vectors of many viral, bacterial, and protozoan pathogens of medical and veterinary importance, ticks harbour a variety of microorganisms which are not known to be pathogenic for vertebrate hosts. Continuous cell lines established from ixodid and argasid ticks could be infected with such endosymbiotic bacteria and endogenous viruses, but to date very few cell lines have been examined for their presence. DNA and RNA extracted from over 50 tick cell lines deposited in the Roslin Wellcome Trust Tick Cell Biobank ( were screened for presence of bacteria and RNA viruses, respectively. Sequencing of PCR products amplified using pan-16S rRNA primers revealed the presence of DNA sequences from bacterial endosymbionts in several cell lines derived from Amblyomma and Dermacentor spp. ticks. Identification to species level was attempted using Rickettsia- and Francisella-specific primers. Pan-Nairovirus primers amplified PCR products of uncertain specificity in cell lines derived from Rhipicephalus, Hyalomma, Ixodes, Carios, and Ornithodoros spp. ticks. Further characterisation attempted with primers specific for Crimean-Congo haemorrhagic fever virus segments confirmed the absence of this arbovirus in the cells. A set of pan-Flavivirus primers did not detect endogenous viruses in any of the cell lines. Transmission electron microscopy revealed the presence of endogenous reovirus-like viruses in many of the cell lines; only 4 of these lines gave positive results with primers specific for the tick Orbivirus St Croix River virus, indicating that there may be additional, as yet undescribed 'tick-only' viruses inhabiting tick cell lines.
Original languageEnglish
Pages (from-to)137-146
Number of pages10
JournalTicks and tick-borne diseases
Issue number3
Early online date30 Jun 2012
Publication statusPublished - 2012
EventProceedings of the 7th International Ticks and Tick-borne Pathogens (TTP7) Conference Zaragosa, Spain - Zaragosa, Spain
Duration: 28 Aug 20112 Sep 2011


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