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Martyn C, Hayes BM, Lauko D, Midthun E, Castaneda G, Bosco-Lauth A, Salkeld DJ, Kistler A, Pollard KS, Chou S. Metatranscriptomic investigation of single Ixodes pacificus ticks reveals diverse microbes, viruses, and novel mRNA-like endogenous viral elements. mSystems 2024:e0032124. [PMID: 38742892 DOI: 10.1128/msystems.00321-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Accepted: 03/27/2024] [Indexed: 05/16/2024] Open
Abstract
Ticks are increasingly important vectors of human and agricultural diseases. While many studies have focused on tick-borne bacteria, far less is known about tick-associated viruses and their roles in public health or tick physiology. To address this, we investigated patterns of bacterial and viral communities across two field populations of western black-legged ticks (Ixodes pacificus). Through metatranscriptomic analysis of 100 individual ticks, we quantified taxon prevalence, abundance, and co-occurrence with other members of the tick microbiome. In addition to commonly found tick-associated microbes, we assembled 11 novel RNA virus genomes from Rhabdoviridae, Chuviridae, Picornaviridae, Phenuiviridae, Reoviridae, Solemovidiae, Narnaviridae and two highly divergent RNA virus genomes lacking sequence similarity to any known viral families. We experimentally verified the presence of these in I. pacificus ticks across several life stages. We also unexpectedly identified numerous virus-like transcripts that are likely encoded by tick genomic DNA, and which are distinct from known endogenous viral element-mediated immunity pathways in invertebrates. Taken together, our work reveals that I. pacificus ticks carry a greater diversity of viruses than previously appreciated, in some cases resulting in evolutionarily acquired virus-like transcripts. Our findings highlight how pervasive and intimate tick-virus interactions are, with major implications for both the fundamental biology and vectorial capacity of I. pacificus ticks. IMPORTANCE Ticks are increasingly important vectors of disease, particularly in the United States where expanding tick ranges and intrusion into previously wild areas has resulted in increasing human exposure to ticks. Emerging human pathogens have been identified in ticks at an increasing rate, and yet little is known about the full community of microbes circulating in various tick species, a crucial first step to understanding how they interact with each and their tick host, as well as their ability to cause disease in humans. We investigated the bacterial and viral communities of the Western blacklegged tick in California and found 11 previously uncharacterized viruses circulating in this population.
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Affiliation(s)
- Calla Martyn
- Department of Biochemistry & Biophysics, University of California-San Francisco, San Francisco, California, USA
- Gladstone Institute of Data Science & Biotechnology, San Francisco, California, USA
| | - Beth M Hayes
- Department of Biochemistry & Biophysics, University of California-San Francisco, San Francisco, California, USA
- One Health Institute, Colorado State University-Fort Collins, Fort Collins, Colorado, USA
| | - Domokos Lauko
- Department of Biochemistry & Biophysics, University of California-San Francisco, San Francisco, California, USA
| | - Edward Midthun
- Department of Biomedical Sciences, Colorado State University-Fort Collins, Fort Collins, Colorado, USA
| | - Gloria Castaneda
- Chan Zuckerberg Biohub, San Francisco, San Francisco, California, USA
| | - Angela Bosco-Lauth
- Department of Biomedical Sciences, Colorado State University-Fort Collins, Fort Collins, Colorado, USA
| | - Daniel J Salkeld
- Department of Biology, Colorado State University-Fort Collins, Fort Collins, Colorado, USA
| | - Amy Kistler
- Chan Zuckerberg Biohub, San Francisco, San Francisco, California, USA
| | - Katherine S Pollard
- Gladstone Institute of Data Science & Biotechnology, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, San Francisco, California, USA
- Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, California, USA
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California-San Francisco, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, San Francisco, California, USA
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Militzer N, Pinecki Socias S, Nijhof AM. Changes in the Ixodes ricinus microbiome associated with artificial tick feeding. Front Microbiol 2023; 13:1050063. [PMID: 36704557 PMCID: PMC9871825 DOI: 10.3389/fmicb.2022.1050063] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/16/2022] [Indexed: 01/11/2023] Open
Abstract
Artificial tick feeding systems (ATFS) can be used to study tick biology and tick-pathogen interactions. Due to the long feeding duration of hard ticks, antibiotics are commonly added to the in vitro blood meal to prevent the blood from decaying. This may affect the ticks' microbiome, including mutualistic bacteria that play an important role in tick biology. This effect was examined by the consecutive feeding of Ixodes ricinus larvae, nymphs, and adults in vitro with and without the supplementation of gentamicin and in parallel on calves. DNA extracted from unfed females was analyzed by 16S rRNA sequencing. The abundance of Candidatus Midichloria mitochondrii, Rickettsia helvetica and Spiroplasma spp. was measured by qPCR in unfed larvae, nymphs, and adults. Larvae and nymphs fed on calves performed significantly better compared to both in vitro groups. Adults fed on blood supplemented with gentamicin and B vitamins had a higher detachment proportion and weight compared to the group fed with B vitamins but without gentamicin. The detachment proportion and weights of females did not differ significantly between ticks fed on calves and in vitro with gentamicin, but the fecundity was significantly higher in ticks fed on calves. 16S rRNA sequencing showed a higher microbiome species richness in ticks fed on calves compared to ticks fed in vitro. A shift in microbiome composition, with Ca. Midichloria mitochondrii as dominant species in females fed as juveniles on calves and R. helvetica as the most abundant species in females previously fed in vitro was observed. Females fed in vitro without gentamicin showed significant lower loads of Ca. M. mitochondrii compared to females fed in vitro with gentamicin and ticks fed on calves. Spiroplasma spp. were exclusively detected in female ticks fed on cattle by qPCR, but 16S rRNA sequencing results also showed a low abundance in in vitro females exposed to gentamicin. In conclusion, the employed feeding method and gentamicin supplementation affected the ticks' microbiome composition and fecundity. Since these changes may have an impact on tick biology and vector competence, they should be taken into account in studies employing ATFS.
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Affiliation(s)
- Nina Militzer
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Sophia Pinecki Socias
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ard M. Nijhof
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany,Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany,*Correspondence: Ard M. Nijhof, ✉
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Thorpe CJ, Wang XR, Munderloh UG, Kurtti TJ. Tick Cell Culture Analysis of Growth Dynamics and Cellular Tropism of Rickettsia buchneri, an Endosymbiont of the Blacklegged Tick, Ixodes scapularis. INSECTS 2021; 12:968. [PMID: 34821769 PMCID: PMC8626015 DOI: 10.3390/insects12110968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 11/23/2022]
Abstract
The blacklegged tick, Ixodes scapularis, a species of significant importance to human and animal health, harbors an endosymbiont Rickettsia buchneri sensu stricto. The symbiont is largely restricted to the ovaries, but all life stages can harbor various quantities or lack R. buchneri entirely. The endosymbiont is cultivable in cell lines isolated from embryos of Ixodes ticks. Rickettsia buchneri most readily grows and is maintained in the cell line IRE11 from the European tick, Ixodes ricinus. The line was characterized by light and electron microscopy and used to analyze the growth dynamics of wildtype and GFPuv-expressing R. buchneri. qPCR indicated that the genome copy doubling time in IRE11 was >7 days. Measurements of fluorescence using a plate reader indicated that the amount of green fluorescent protein doubled every 11 days. Two 23S rRNA probes were tested via RNA FISH on rickettsiae grown in vitro and adapted to evaluate the tissue tropism of R. buchneri in field-collected female I. scapularis. We observed strong positive signals of R. buchneri in the ovaries and surrounding the nucleus of the developing oocytes. Tissue tropism in I. scapularis and in vitro growth dynamics strengthen the contemporary understanding of R. buchneri as a transovarially transmitted, non-pathogenic endosymbiont.
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Affiliation(s)
- Cody J. Thorpe
- Department of Entomology, University of Minnesota, Saint Paul, MN 55108, USA; (X.-R.W.); (U.G.M.)
| | | | | | - Timothy J. Kurtti
- Department of Entomology, University of Minnesota, Saint Paul, MN 55108, USA; (X.-R.W.); (U.G.M.)
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Salata C, Moutailler S, Attoui H, Zweygarth E, Decker L, Bell-Sakyi L. How relevant are in vitro culture models for study of tick-pathogen interactions? Pathog Glob Health 2021; 115:437-455. [PMID: 34190676 PMCID: PMC8635668 DOI: 10.1080/20477724.2021.1944539] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Although tick-borne infectious diseases threaten human and animal health worldwide, with constantly increasing incidence, little knowledge is available regarding vector-pathogen interactions and pathogen transmission. In vivo laboratory study of these subjects using live, intact ticks is expensive, labor-intensive, and challenging from the points of view of biosafety and ethics. Several in vitro models have been developed, including over 70 continuous cell lines derived from multiple tick species and a variety of tick organ culture systems, facilitating many research activities. However, some limitations have to be considered in the translation of the results from the in vitro environment to the in vivo situation of live, intact ticks, and vertebrate hosts. In this review, we describe the available in vitro models and selected results from their application to the study of tick-borne viruses, bacteria, and protozoa, where possible comparing these results to studies in live, intact ticks. Finally, we highlight the strengths and weaknesses of in vitro tick culture models and their essential role in tick-borne pathogen research.
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Affiliation(s)
- Cristiano Salata
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Sara Moutailler
- Laboratoire De Santé Animale, Anses, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Maisons-Alfort, France
| | - Houssam Attoui
- Department of Animal Health, UMR1161 Virologie, INRAE, Ecole Nationale Vétérinaire d’Alfort, ANSES, Université Paris-Est, Maisons-Alfort, France
| | - Erich Zweygarth
- The Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
| | - Lygia Decker
- Department of Preventive Veterinary Medicine, School of Veterinary Medicine, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Lesley Bell-Sakyi
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
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