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Bowden AC, Allbaugh RA, Gall AJ, Costa MDO, Leis M, Sebbag L. Ocular diagnostics, ophthalmic findings, and conjunctival microbiome in the Chilean flamingo (Phoenicopterus chilensis). Vet Ophthalmol 2024. [PMID: 38880760 DOI: 10.1111/vop.13242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 06/18/2024]
Abstract
OBJECTIVE To establish normative data for selected ocular diagnostic tests and commensal conjunctival microflora and describe the incidence of ocular pathology in Chilean flamingos. ANIMALS STUDIED A total of 41 Chilean flamingos were examined at the Blank Park Zoo in Des Moines, Iowa. PROCEDURES In 20 flamingos, blink rate was assessed undisturbed in their exhibit, then gentle manual restraint was used to assess palpebral fissure length (PFL), aqueous tear production (phenol red thread test [PRTT] in one eye, endodontic absorbent paper point tear test [EAPPTT] in the other), intraocular pressure (IOP; rebound tonometry), and fluorescein staining. Twenty-one other flamingos were brought to a darkened area for neuro-ophthalmic examination, slit lamp biomicroscopy, and indirect ophthalmoscopy. Swabs from seven flamingos were used for ocular microbiome evaluation. RESULTS Results are presented as mean ± standard deviation (range). Flamingos comprised 23 females/18 males, aged 11 ± 9.1 (0.7-40) years. Test results: blink rate, 3.7 ± 2 (1-9) blinks/min; PFL, 11.2 ± 1.2 (9-14) mm; IOP, 14 ± 3.2 (10-22) mmHg; EAPPT, 10.2 ± 2.8 (9-14) mm/min; PRTT, 6.8 ± 2.5 (3-13) mm/15 s. Dazzle reflex was positive in four birds examined. Pathologies included cataracts (n = 7 birds), corneal fibrosis (n = 3), endothelial pigment (n = 2), uveal cysts (n = 1), lens luxation (n = 1), and uveitis (n = 1). Ocular microbiome showed high diversity of taxa. CONCLUSIONS Baseline ocular parameters and incidence of ophthalmic pathology assist veterinarians with disease screening for Chilean flamingos, while the ocular microbiome showed high diversity.
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Affiliation(s)
- Anna Catherine Bowden
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Rachel A Allbaugh
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | | | - Matheus de O Costa
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Faculty of Veterinary Medicine, Population Clinical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Marina Leis
- Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Lionel Sebbag
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel
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2
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Kong W, Yang P, Ding G, Cheng G, Xu Z. Elucidating the dynamic immune responses within the ocular mucosa of rainbow trout ( Oncorhynchus mykiss) after infection with Flavobacterium columnare. Front Immunol 2023; 14:1288223. [PMID: 38077363 PMCID: PMC10702956 DOI: 10.3389/fimmu.2023.1288223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 10/26/2023] [Indexed: 12/18/2023] Open
Abstract
The eye of vertebrates is constantly faced with numerous challenges from aquatic or airborne pathogens. As a crucial first line of defense, the ocular mucosa (OM) protects the visual organ from external threats in vertebrates such as birds and mammals. However, the understanding of ocular mucosal immunity in early vertebrates, such as teleost fish, remains limited, particularly concerning their resistance to bacterial infections. To gain insights into the pivotal role of the OM in antibacterial immunity among teleost fish, we developed a bacterial infection model using Flavobacterium columnare in rainbow trout (Oncorhynchus mykiss). Here the qPCR and immunofluorescence results showed that F. columnare could invade trout OM, suggesting that the OM could be a primary target and barrier for the bacteria. Moreover, immune-related genes (il-6, il-8, il-11, cxcl10, nod1, il1-b, igm, igt, etc.) were upregulated in the OM of trout following F. columnare infection, as confirmed by qPCR, which was further proved through RNA-seq. The results of transcriptome analyses showed that bacterial infection critically triggers a robust immune response, including innate, and adaptive immune-related signaling pathways such as Toll-like, NOD-like, and C-type lectin receptor signaling pathway and immune network for IgA production, which underscores the immune role of the OM in bacterial infection. Interestingly, a substantial reduction in the expression of genes associated with visual function was observed after infection, indicating that bacterial infection could impact ocular function. Overall, our findings have unveiled a robust mucosal immune response to bacterial infection in the teleost OM for the first time, providing valuable insights for future research into the mechanisms and functions of ocular mucosal immunity in early vertebrate species.
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Affiliation(s)
- Weiguang Kong
- Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Peng Yang
- Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Guangyi Ding
- Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Gaofeng Cheng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Zhen Xu
- Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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3
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Bendlin A, Gemensky-Metzler AJ, Diaz-Campos D, Newbold GM, Miller EJ, Chandler HL. Evaluation of a commercial NGS service for detection of bacterial and fungal pathogens in infectious ulcerative keratitis. Vet Ophthalmol 2023; 26:500-513. [PMID: 36943705 DOI: 10.1111/vop.13069] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 01/16/2023] [Accepted: 01/28/2023] [Indexed: 03/23/2023]
Abstract
OBJECTIVES To compare results from a commercial next-generation sequencing (NGS) service to corneal cytology and culture for identification of causative organisms in veterinary patients presenting for infectious ulcerative keratitis (IUK). PROCEDURE Swabs for corneal aerobic and fungal cultures and DNA swabs for NGS were submitted for canine and equine normal controls (n = 11 and n = 4, respectively) and IUK patients (n = 22 and n = 8, respectively) for which microbrush cytology specimens confirmed the presence of infectious organisms. The sensitivity of the NGS results was compared with bacterial and fungal culture results. Concordance between the NGS and culture results was determined. RESULTS The NGS results were positive for bacterial and fungal organisms in 5 and 1 normal and 18 and 1 IUK cases, respectively. Bacterial and fungal cultures were positive for 7 and 2 normal and 20 and 5 IUK cases, respectively. Sensitivity of NGS was 82.14% (95% confidence interval (CI), 63.11% to 93.94%) and specificity was 76.47% (95% CI, 50.10% to 93.19%). Concordance (complete and partial) between identified bacterial and fungal organisms was found in 79% and 100% of cases, respectively. NGS identified organisms in 3 culture-negative IUK samples. CONCLUSION A commercial NGS service may be useful in the identification of causative agents in IUK cases with a sensitivity greater than the sensitivity previously reported for aerobic culture. Further testing is needed to determine the clinical significance of additional organisms isolated by NGS from infected cases, as well as organisms isolated from normal corneas.
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Affiliation(s)
- Ashley Bendlin
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
| | | | - Dubraska Diaz-Campos
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Georgina M Newbold
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Eric J Miller
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Heather L Chandler
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
- College of Optometry, The Ohio State University, Columbus, Ohio, USA
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4
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Weitzman CL, Belden LK, May M, Langager MM, Dalloul RA, Hawley DM. Antibiotic perturbation of gut bacteria does not significantly alter host responses to ocular disease in a songbird species. PeerJ 2022; 10:e13559. [PMID: 35707121 PMCID: PMC9190666 DOI: 10.7717/peerj.13559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/19/2022] [Indexed: 01/17/2023] Open
Abstract
Bacterial communities in and on wild hosts are increasingly appreciated for their importance in host health. Through both direct and indirect interactions, bacteria lining vertebrate gut mucosa provide hosts protection against infectious pathogens, sometimes even in distal body regions through immune regulation. In house finches (Haemorhous mexicanus), the bacterial pathogen Mycoplasma gallisepticum (MG) causes conjunctivitis, with ocular inflammation mediated by pro- and anti-inflammatory cytokines and infection triggering MG-specific antibodies. Here, we tested the role of gut bacteria in host responses to MG by using oral antibiotics to perturb bacteria in the gut of captive house finches prior to experimental inoculation with MG. We found no clear support for an impact of gut bacterial disruption on conjunctival pathology, MG load, or plasma antibody levels. However, there was a non-significant trend for birds with intact gut communities to have greater conjunctival pathology, suggesting a possible impact of gut bacteria on pro-inflammatory cytokine stimulation. Using 16S bacterial rRNA amplicon sequencing, we found dramatic differences in cloacal bacterial community composition between captive, wild-caught house finches in our experiment and free-living finches from the same population, with lower bacterial richness and core communities composed of fewer genera in captive finches. We hypothesize that captivity may have affected the strength of results in this experiment, necessitating further study with this consideration. The abundance of anthropogenic impacts on wildlife and their bacterial communities, alongside the emergence and spread of infectious diseases, highlights the importance of studies addressing the role of commensal bacteria in health and disease, and the consequences of gut bacterial shifts on wild hosts.
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Affiliation(s)
- Chava L. Weitzman
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America,Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Lisa K. Belden
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
| | - Meghan May
- Department of Biomedical Sciences, University of New England, Biddeford, ME, United States of America
| | - Marissa M. Langager
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
| | - Rami A. Dalloul
- Department of Poultry Science, University of Georgia, Athens, GA, United States of America
| | - Dana M. Hawley
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
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5
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Weitzman CL, Rostama B, Thomason CA, May M, Belden LK, Hawley DM. Experimental test of microbiome protection across pathogen doses reveals importance of resident microbiome composition. FEMS Microbiol Ecol 2021; 97:6385755. [PMID: 34626186 DOI: 10.1093/femsec/fiab141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/07/2021] [Indexed: 01/04/2023] Open
Abstract
The commensal microbes inhabiting a host tissue can interact with invading pathogens and host physiology in ways that alter pathogen growth and disease manifestation. Prior work in house finches (Haemorhous mexicanus) found that resident ocular microbiomes were protective against conjunctival infection and disease caused by a relatively high dose of Mycoplasma gallisepticum. Here, we used wild-caught house finches to experimentally examine whether protective effects of the resident ocular microbiome vary with the dose of invading pathogen. We hypothesized that commensal protection would be strongest at low M. gallisepticum inoculation doses because the resident microbiome would be less disrupted by invading pathogen. Our five M. gallisepticum dose treatments were fully factorial with an antibiotic treatment to perturb resident microbes just prior to M. gallisepticum inoculation. Unexpectedly, we found no indication of protective effects of the resident microbiome at any pathogen inoculation dose, which was inconsistent with the prior work. The ocular bacterial communities at the beginning of our experiment differed significantly from those previously reported in local wild-caught house finches, likely causing this discrepancy. These variable results underscore that microbiome-based protection in natural systems can be context dependent, and natural variation in community composition may alter the function of resident microbiomes in free-living animals.
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Affiliation(s)
- Chava L Weitzman
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA
| | - Bahman Rostama
- Department of Biomedical Sciences, University of New England, Biddeford - 04005, ME, USA
| | - Courtney A Thomason
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA.,Division of Remediation, Tennessee Department of Environment and Conservation, Oak Ridge - 37830, TN, USA
| | - Meghan May
- Department of Biomedical Sciences, University of New England, Biddeford - 04005, ME, USA
| | - Lisa K Belden
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA
| | - Dana M Hawley
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA
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6
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The porcine corneal surface bacterial microbiome: A distinctive niche within the ocular surface. PLoS One 2021; 16:e0247392. [PMID: 33606829 PMCID: PMC7895408 DOI: 10.1371/journal.pone.0247392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 02/05/2021] [Indexed: 02/08/2023] Open
Abstract
Purpose The ocular surface microbiome has been described as paucibacterial. Until now, studies investigating the bacterial community associated with the ocular surface through high-throughput sequencing have focused on the conjunctiva. Conjunctival samples are thought to reflect and be representative of the microbiome residing on the ocular surface, including the cornea. Here, we hypothesized that the bacterial community associated with the corneal surface was different from those of the inferonasal and superotemporal conjunctival fornices, and from the tear film. Methods Both eyes from 15 healthy piglets were sampled using swabs (inferonasal fornix, superotemporal fornix, and corneal surface, n = 30 each) and Schirmer tear test strips (STT, n = 30). Negative sampling controls (swabs and STT, n = 2 each) and extraction controls (n = 4) were included. Total DNA was extracted and high-throughput sequencing targeting the 16S rRNA gene was performed. Bioinformatic analyses included multiple contamination-controlling steps. Results Corneal surface samples had a significantly lower number of taxa detected (P<0.01) and were compositionally different from all other sample types (Bray-Curtis dissimilarity, P<0.04). It also harbored higher levels of Proteobacteria (P<0.05), specifically Brevundimonas spp. (4.1-fold) and Paracoccus spp. (3.4-fold) than other sample types. Negative control STT strip samples yielded the highest amount of 16S rRNA gene copies across all sample types (P<0.05). Conclusions Our data suggests that the corneal surface provides a distinct environmental niche within the ocular surface, leading to a bacterial community compositionally different from all other sample types.
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7
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Scott EM, Lewin AC, Leis ML. Current ocular microbiome investigations limit reproducibility and reliability: Critical review and opportunities. Vet Ophthalmol 2020; 24:4-11. [PMID: 33382917 DOI: 10.1111/vop.12854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/13/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022]
Abstract
Enthusiasm for research describing microbial communities using next-generation sequencing (NGS) has outpaced efforts to standardize methodology. Without consistency in the way research is carried out in this field, the comparison of data between studies is near impossible and the utility of results remains limited. This holds true for bacterial microbiome research of the ocular surface, and other sites, in both humans and animals. In addition, the ocular surface remains under-explored when compared to other mucosal sites. Low bacterial biomass samples from the ocular surface lead to further technical challenges. Taken together, two major problems were identified: (1) Normalization of the workflow in studies utilizing NGS to investigate the ocular surface bacteriome is necessary in order to propel the field forward and improve research impact through cross-study comparisons. (2) Current microbiome profiling technology was developed for high bacterial biomass samples (such as feces or soil), posing a challenge for analyses of samples with low bacterial load such as the ocular surface. This article reviews the challenges and limitations currently facing ocular microbiome research and provides recommendations for minimum reporting standards for veterinary ophthalmologists and clinician scientists to limit inter-study variation, improve reproducibility, and ultimately render results from these studies more impactful. The move toward normalization of methodology will expedite and maximize the potential for microbiome research to translate into meaningful discovery and tangible clinical applications.
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Affiliation(s)
- Erin M Scott
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA
| | - Andrew C Lewin
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Marina L Leis
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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8
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Li JJ, Yi S, Wei L. Ocular Microbiota and Intraocular Inflammation. Front Immunol 2020; 11:609765. [PMID: 33424865 PMCID: PMC7786018 DOI: 10.3389/fimmu.2020.609765] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/23/2020] [Indexed: 12/20/2022] Open
Abstract
The term ocular microbiota refers to all types of commensal and pathogenic microorganisms present on or in the eye. The ocular surface is continuously exposed to the environment and harbors various commensals. Commensal microbes have been demonstrated to regulate host metabolism, development of immune system, and host defense against pathogen invasion. An unbalanced microbiota could lead to pathogenic microbial overgrowth and cause local or systemic inflammation. The specific antigens that irritate the deleterious immune responses in various inflammatory eye diseases remain obscure, while recent evidence implies a microbial etiology of these illnesses. The purpose of this review is to provide an overview of the literature on ocular microbiota and the role of commensal microbes in several eye diseases. In addition, this review will also discuss the interaction between microbial pathogens and host factors involved in intraocular inflammation, and evaluate therapeutic potential of targeting ocular microbiota to treat intraocular inflammation.
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Affiliation(s)
- Jing Jing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Sanjun Yi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lai Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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9
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LaFrentz S, Abarca E, Mohammed HH, Cuming R, Arias CR. Characterization of the normal equine conjunctival bacterial community using culture-independent methods. Vet Ophthalmol 2020; 23:480-488. [PMID: 32017364 DOI: 10.1111/vop.12743] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 12/10/2019] [Accepted: 12/30/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND The equine conjunctival microbiota has often been reported to be dominated by Gram-positive species such as Staphylococcus sp., Bacillus sp., and Corynebacterium sp. However, traditional culture-based methods can only recover a fraction of the bacterial species present in the sample. OBJECTIVES This pilot study aimed at exploring the diversity of the equine conjunctival microbiota using culture-independent methods. STUDY DESIGN Eight horses were included in this study, and only eyes with normal ophthalmic examination (n = 15 eyes) were sampled. METHODS Conjunctival biopsies (culture-independent) were collected, and DNA was extracted from the tissues. Bacterial communities in conjunctival biopsies were characterized by next-generation sequencing of the 16S rRNA genes. Individual reads were ascribed to operational taxonomic units (OTUs) using BLASTn and Greengenes databases. Species richness, evenness, and Good's coverage were determined for each conjunctiva-associated microbial community. RESULTS Culture-independent samples produced a total of 329 bacterial OTUs. The main OTUs identified in the study belonged to the Gram-negative species Ralstonia mannitolilytica (88.0%), Nicoletella semolina (3.3%), and Pseudomonas tolaasii (1.5%). CONCLUSIONS Contrary to previously published data based on culture-dependent methods, the horse eye microbial community was dominated by Gram-negative bacteria of the phylum Proteobacteria.
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Affiliation(s)
- Stacey LaFrentz
- School of Fisheries, Aquaculture and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, USA
| | - Eva Abarca
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
| | - Haitham H Mohammed
- School of Fisheries, Aquaculture and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, USA
| | - Rosemary Cuming
- School of Fisheries, Aquaculture and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, USA
| | - Covadonga R Arias
- School of Fisheries, Aquaculture and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, USA
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10
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Borroni D, Romano V, Kaye SB, Somerville T, Napoli L, Fasolo A, Gallon P, Ponzin D, Esposito A, Ferrari S. Metagenomics in ophthalmology: current findings and future prospectives. BMJ Open Ophthalmol 2019; 4:e000248. [PMID: 31276030 PMCID: PMC6557081 DOI: 10.1136/bmjophth-2018-000248] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 02/04/2019] [Accepted: 02/19/2019] [Indexed: 01/14/2023] Open
Abstract
Less than 1% of all microorganisms of the available environmental microbiota can be cultured with the currently available techniques. Metagenomics is a new methodology of high-throughput DNA sequencing, able to provide taxonomic and functional profiles of microbial communities without the necessity to culture microbes in the laboratory. Metagenomics opens to a ‘hypothesis-free’ approach, giving important details for future research and treatment of ocular diseases in ophthalmology, such as ocular infection and ocular surface diseases.
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Affiliation(s)
- Davide Borroni
- St Paul's Eye Unit, Department of Corneal and External Eye Diseases, Royal Liverpool University Hospital, Liverpool, United Kingdom.,Department of Doctoral Studies, Riga Stradins University, Riga, Latvia.,Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom.,Fondazione Banca Degli Occhi Del Veneto Onlus, Zelarino, Venezia, Italy
| | - Vito Romano
- St Paul's Eye Unit, Department of Corneal and External Eye Diseases, Royal Liverpool University Hospital, Liverpool, United Kingdom.,Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom
| | - Stephen B Kaye
- St Paul's Eye Unit, Department of Corneal and External Eye Diseases, Royal Liverpool University Hospital, Liverpool, United Kingdom.,Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom
| | - Tobi Somerville
- St Paul's Eye Unit, Department of Corneal and External Eye Diseases, Royal Liverpool University Hospital, Liverpool, United Kingdom.,Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom
| | - Luca Napoli
- Dipartimento di Specialità Medico-Chirurgiche, Scienze Radiologiche e Sanita Pubblica, Universita degli Studi di Brescia, Brescia, Italy
| | - Adriano Fasolo
- Fondazione Banca Degli Occhi Del Veneto Onlus, Zelarino, Venezia, Italy
| | - Paola Gallon
- Fondazione Banca Degli Occhi Del Veneto Onlus, Zelarino, Venezia, Italy
| | - Diego Ponzin
- Fondazione Banca Degli Occhi Del Veneto Onlus, Zelarino, Venezia, Italy
| | - Alfonso Esposito
- Centre for Integrative Biology (CIBIO), Trento University, Trento, Italy
| | - Stefano Ferrari
- Fondazione Banca Degli Occhi Del Veneto Onlus, Zelarino, Venezia, Italy
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11
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Banks KC, Ericsson AC, Reinero CR, Giuliano EA. Veterinary ocular microbiome: Lessons learned beyond the culture. Vet Ophthalmol 2019; 22:716-725. [PMID: 31070001 DOI: 10.1111/vop.12676] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/27/2019] [Accepted: 04/12/2019] [Indexed: 01/08/2023]
Abstract
Ocular pathogens cause many painful and vision-threatening diseases such as infectious keratitis, uveitis, and endophthalmitis. While virulent pathogens and pathobionts play important roles in disease pathogenesis, the scientific community has long assumed disruption of the ocular surface occurs prior to microbial colonization and subsequent infection. While nonpathogenic bacteria are often detected in corneal and conjunctival cultures from healthy eyes, cultures also frequently fail to yield growth of common ocular pathogens or nonpathogenic bacteria. This prompts the following question: Is the ocular surface populated by a stable microbial population that cannot be detected using standard culture techniques? The study of the microbiome has recently become a widespread focus in physician and veterinary medicine. Research suggests a pivotal symbiotic relationship with these microbes to maintain healthy host tissues, and when altered is associated with various disease states ("dysbiosis"). The microbiota that lives within and on mammalian bodies have long been known to influence health and susceptibility to infection. However, limitations of traditional culture methods have resulted in an incomplete understanding of what many now call the "forgotten organ," that is, the microbiome. With the introduction of high-throughput sequencing, physician ophthalmology has recognized an ocular surface with much more diverse microbial communities than suspected based on traditional culture. This article reviews the salient features of the ocular surface microbiome and highlights important future applications following the advent of molecular techniques for microbial identification, including characterizing ocular surface microbiomes in our veterinary species and their potential role in management of infectious and inflammatory ocular diseases.
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Affiliation(s)
- Kayla C Banks
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Aaron C Ericsson
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri
| | - Carol R Reinero
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Elizabeth A Giuliano
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
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12
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Weitzman CL, Sandmeier FC, Tracy CR. Host species, pathogens and disease associated with divergent nasal microbial communities in tortoises. ROYAL SOCIETY OPEN SCIENCE 2018; 5:181068. [PMID: 30473851 PMCID: PMC6227988 DOI: 10.1098/rsos.181068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/18/2018] [Indexed: 06/09/2023]
Abstract
Diverse bacterial communities are found on every surface of macro-organisms, and they play important roles in maintaining normal physiological functions in their hosts. While the study of microbiomes has expanded with the influx of data enabled by recent technological advances, microbiome research in reptiles lags behind other organisms. We sequenced the nasal microbiomes in a sample of four North American tortoise species, and we found differing community compositions among tortoise species and sampling sites, with higher richness and diversity in Texas and Sonoran desert tortoises. Using these data, we investigated the prevalence and operational taxonomic unit (OTU) diversity of the potential pathogen Pasteurella testudinis and found it to be common, abundant and highly diverse. However, the presence of this bacterium was not associated with differences in bacterial community composition within host species. We also found that the presence of nasal discharge from tortoises at the time of sampling was associated with a decline in diversity and a change in microbiome composition, which we posit is due to the harsh epithelial environment associated with immune responses. Repeated sampling across seasons, and at different points of pathogen colonization, should contribute to our understanding of the causes and consequences of different bacterial communities in these long-lived hosts.
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Affiliation(s)
- Chava L. Weitzman
- Department of Biology, University of Nevada, Reno, NV 89557, USA
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV 89557, USA
| | | | - C. Richard Tracy
- Department of Biology, University of Nevada, Reno, NV 89557, USA
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Leis ML, Costa MO. Initial description of the core ocular surface microbiome in dogs: Bacterial community diversity and composition in a defined canine population. Vet Ophthalmol 2018; 22:337-344. [PMID: 30095241 DOI: 10.1111/vop.12599] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To characterize the bacterial community residing on the conjunctiva of clinically healthy dogs. METHODS Bacterial DNA from conjunctival swabs of 10 dogs with normal ocular examinations (both OD and OS, n = 20) was extracted, and 16S rRNA amplicons were sequenced using Illumina MiSeq 600. Resulting data were subjected to quality control steps, and analyzed for bacterial community richness and diversity, within- and between-group dissimilarity, and relative taxonomic composition. RESULTS High-quality reads (2.22 million bp) resulted in a mean of 159 068 sequences per sample. Bacterial community evenness and diversity was high when compared to other species, and did not significantly differ when samples were grouped by dogs or eyes. As expected, within-dog samples were more similar than between-dog samples. Taxonomic classification revealed that >95% of the community consisted of Firmicutes (34.9 ± 8.8%), Actinobacteria (26.3 ± 7.1%), Proteobacteria (26.2 ± 6.6%), and Bacteroidetes (9.4 ± 2.4%). Key members of the dog ocular surface microbiome, found in all dogs and corresponding to >25% of all identified OTUs (operational taxonomic units), were part of the Bifidobacteriaceae, Lachnospiraceae, Moraxellaceae, Corynebacteriaceae families. Genera previously thought to account for the majority of the core ocular surface microbiome in the dog (Staphylococcus sp., Streptococcus sp., and Bacillus sp.) were associated with only 2.63% of overall reads. CONCLUSIONS This study shows the feasibility of conjunctival swabs and high-throughput sequencing to profile the bacterial community structure of the canine ocular surface. A core ocular surface microbiome was identified for this canine population.
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Affiliation(s)
- Marina L Leis
- Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Matheus O Costa
- Faculty of Veterinary Medicine, Department of Farm Animal Health, Utrecht University, Utrecht, Netherlands.,Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Knutie SA. Relationships among introduced parasites, host defenses, and gut microbiota of Galapagos birds. Ecosphere 2018. [DOI: 10.1002/ecs2.2286] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs Connecticut 06269 USA
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Leon AE, Hawley DM. Host Responses to Pathogen Priming in a Natural Songbird Host. ECOHEALTH 2017; 14:793-804. [PMID: 28766063 PMCID: PMC5726927 DOI: 10.1007/s10393-017-1261-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 06/14/2017] [Accepted: 06/14/2017] [Indexed: 06/07/2023]
Abstract
Hosts in free-living populations can experience substantial variation in the frequency and dose of pathogen exposure, which can alter disease progression and protection from future exposures. In the house finch-Mycoplasma gallisepticum (MG) system, the pathogen is primarily transmitted via bird feeders, and some birds may be exposed to frequent low doses of MG while foraging. Here we experimentally determined how low dose, repeated exposures of house finches to MG influence host responses and protection from secondary high-dose challenge. MG-naive house finches were given priming exposures that varied in dose and total number. After quantifying host responses to priming exposures, all birds were given a secondary high-dose challenge to assess immunological protection. Dose, but not the number of exposures, significantly predicted both infection and disease severity following priming exposure. Furthermore, individuals given higher priming doses showed stronger protection upon secondary, high-dose challenge. However, even single low-dose exposures to MG, a proxy for what some birds likely experience in the wild while feeding, provided significant protection against a high-dose challenge. Our results suggest that bird feeders, which serve as sources of infection in the wild, may in some cases act as "immunizers," with important consequences for disease dynamics.
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Affiliation(s)
- Ariel E Leon
- Department of Biological Sciences, Virginia Tech, 2119 Derring Hall (0406), Blacksburg, VA, 24061, USA.
| | - Dana M Hawley
- Department of Biological Sciences, Virginia Tech, 2119 Derring Hall (0406), Blacksburg, VA, 24061, USA
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Thomason CA, Mullen N, Belden LK, May M, Hawley DM. Resident Microbiome Disruption with Antibiotics Enhances Virulence of a Colonizing Pathogen. Sci Rep 2017; 7:16177. [PMID: 29170421 PMCID: PMC5701009 DOI: 10.1038/s41598-017-16393-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/13/2017] [Indexed: 01/06/2023] Open
Abstract
There is growing evidence that symbiotic microbes play key roles in host defense, but less is known about how symbiotic microbes mediate pathogen-induced damage to hosts. Here, we use a natural wildlife disease system, house finches and the conjunctival bacterial pathogen Mycoplasma gallisepticum (MG), to experimentally examine the impact of the ocular microbiome on host damage and pathogen virulence factors during infection. We disrupted the ocular bacterial community of healthy finches using an antibiotic that MG is intrinsically resistant to, then inoculated antibiotic- and sham-treated birds with MG. House finches with antibiotic-disrupted ocular microbiomes had more severe MG-induced conjunctival inflammation than birds with unaltered microbiomes, even after accounting for differences in conjunctival MG load. Furthermore, MG cultures from finches with disrupted microbiomes had increased sialidase enzyme and cytadherence activity, traits associated with enhanced virulence in Mycoplasmas, relative to isolates from sham-treated birds. Variation in sialidase activity and cytadherence among isolates was tightly linked with degree of tissue inflammation in hosts, supporting the consideration of these traits as virulence factors in this system. Overall, our results suggest that microbial dysbiosis can result in enhanced virulence of colonizing pathogens, with critical implications for the health of wildlife, domestic animals, and humans.
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Affiliation(s)
| | - Nathan Mullen
- Department of Biomedical Sciences, University of New England, Biddeford, ME, USA
| | - Lisa K Belden
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Meghan May
- Department of Biomedical Sciences, University of New England, Biddeford, ME, USA
| | - Dana M Hawley
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
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