title: Coinfection of tick cell lines has variable effects on replication of intracellular bacterial and viral pathogens.
abstract: Ticks transmit various human and animal microbial pathogens and may harbour more than one pathogen simultaneously. Both viruses and bacteria can trigger, and may subsequently suppress, vertebrate host and arthropod vector anti-microbial responses. Microbial coinfection of ticks could lead to an advantage or disadvantage for one or more of the microorganisms. In this preliminary study, cell lines derived from the ticks Ixodes scapularis and Ixodes ricinus were infected sequentially with 2 arthropod-borne pathogens, Borrelia burgdorferi s.s., Ehrlichia ruminantium, or Semliki Forest virus (SFV), and the effect of coinfection on the replication of these pathogens was measured. Prior infection of tick cell cultures with the spirochaete B. burgdorferi enhanced subsequent replication of the rickettsial pathogen E. ruminantium whereas addition of spirochaetes to cells infected with E. ruminantium had no effect on growth of the latter. Both prior and subsequent presence of B. burgdorferi also had a positive effect on SFV replication. Presence of E. ruminantium or SFV had no measurable effect on B. burgdorferi growth. In tick cells infected first with E. ruminantium and then with SFV, virus replication was significantly higher across all time points measured (24, 48, 72h post infection), while presence of the virus had no detectable effect on bacterial growth. When cells were infected first with SFV and then with E. ruminantium, there was no effect on replication of either pathogen. The results of this preliminary study indicate that interplay does occur between different pathogens during infection of tick cells. Further study is needed to determine if this results from direct pathogen-pathogen interaction or from effects on host cell defences, and to determine if these observations also apply in vivo in ticks. If presence of one pathogen in the tick vector results in increased replication of another, this could have implications for disease transmission and incidence.
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK; Department of Infectious Diseases and Neuroinfections, Medical University in Białystok, Żurawia 14, 15-540 Białystok, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Moniuszko
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK.
authors.forename: Claudia
authors.initials: C
authors.lastname: Rückert
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK.
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Alberdi
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK.
authors.forename: Gerald
authors.initials: G
authors.lastname: Barry
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, MS421 Chandler Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Stevenson
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK; The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK.
authors.forename: John K
authors.initials: JK
authors.lastname: Fazakerley
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK.
authors.forename: Alain
authors.initials: A
authors.lastname: Kohl
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, UK. Electronic address: lesley.sakyi@pirbright.ac.uk.
authors.forename: Lesley
authors.initials: L
authors.lastname: Bell-Sakyi
mesh_terms: D018354:Alphavirus Infections / Q000635:transmission* / Q000821:virology; D000818:Animals; D025065:Borrelia burgdorferi / Q000502:physiology*; D002460:Cell Line; D060085:Coinfection; D016995:Ehrlichia ruminantium / Q000502:physiology*; D017930:Genes, Reporter; D006357:Heartwater Disease / Q000382:microbiology / Q000635:transmission*; D006801:Humans; D018884:Ixodes / Q000382:microbiology*; D008193:Lyme Disease / Q000382:microbiology / Q000635:transmission*; D012672:Semliki forest virus / Q000502:physiology*; D014779:Virus Replication
keywords: Borrelia; Coinfection; Ehrlichia; Ixodes spp.; Semliki Forest virus; Tick cell line