Microscopic Visualisation of Zoonotic Arbovirus Replication in Tick Cell and Organ Cultures Using Semliki Forest Virus Reporter Systems.

Lesley Bell-Sakyi,Sabine Weisheit,John Fazakerley,Claudia Rückert,Rennos Fragkoudis,Gerald Barry

doi:10.3390/vetsci3040028

Lesley Bell-Sakyi, Sabine Weisheit + Show 4 more

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https://doi.org/10.3390/vetsci3040028

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Abstract

Ticks are vectors and reservoirs of many arboviruses pathogenic for humans or domestic animals; in addition, during bloodfeeding they can acquire and harbour pathogenic arboviruses normally transmitted by other arthropods such as mosquitoes. Tick cell and organ cultures provide convenient tools for propagation and study of arboviruses, both tick-borne and insect-borne, enabling elucidation of virus-tick cell interaction and yielding insight into the mechanisms behind vector competence and reservoir potential for different arbovirus species. The mosquito-borne zoonotic alphavirus Semliki Forest virus (SFV), which replicates well in tick cells, has been isolated from Rhipicephalus, Hyalomma, and Amblyomma spp. ticks removed from mammalian hosts in East Africa; however nothing is known about any possible role of ticks in SFV epidemiology. Here we present a light and electron microscopic study of SFV infecting cell lines and organ cultures derived from African Rhipicephalus spp. ticks. As well as demonstrating the applicability of these culture systems for studying virus-vector interactions, we provide preliminary evidence to support the hypothesis that SFV is not normally transmitted by ticks because the virus does not infect midgut cells.

Highlights

Ixodid and argasid ticks transmit a wide range of pathogenic arboviruses of medical and/or veterinary importance; most of these are RNA viruses belonging to the families Bunyaviridae, Flaviviridae, and Reoviridae, while a single DNA virus, African swine fever virus of the familyAsfarviridae, is harboured and transmitted by argasid ticks of the genus Ornithodoros [1]
The R. decoloratus tick cell line BDE/CTVM16 [34] at passage level 76 was grown in L-15 (Leibovitz) medium supplemented with 10% tryptose phosphate broth (TPB, Invitrogen, Paisley, UK), 20%
Structures associated with Semliki Forest virus (SFV) replication and production were clearly visible by electron microscopy (EM) in tick, mosquito, and mammalian cells infected with SFV4(3F)-ZsGreen

Summary

Introduction

Ixodid and argasid ticks transmit a wide range of pathogenic arboviruses of medical and/or veterinary importance; most of these are RNA viruses belonging to the families Bunyaviridae, Flaviviridae, and Reoviridae, while a single DNA virus, African swine fever virus of the familyAsfarviridae, is harboured and transmitted by argasid ticks of the genus Ornithodoros [1]. Other putative endogenous tick viruses have only been detected by electron microscopy in cultured tick cells [4,5,6], as partial RNA sequences identified through high-throughput screening of field tick samples (reviewed by [7]), or as partial DNA sequences present in tick genomes [8]. A fourth group of viruses detected in ticks by in vitro isolation and/or molecular techniques comprises arboviruses that are normally transmitted by other arthropods, in particular mosquitoes. These include zoonotic pathogens such as West Nile virus, Rift Valley fever virus, and chikungunya virus [9,10,11]

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