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Legere RM, Poveda C, Ott JA, Bray JM, Villafone EG, Silveira BPD, Kahn SK, Martin CL, Mancino C, Taraballi F, Criscitiello MF, Berghman L, Bordin AI, Pollet J, Cohen ND. Intramuscular but not nebulized administration of a mRNA vaccine against Rhodococcus equi stimulated humoral immune responses in neonatal foals. Am J Vet Res 2024; 85:ajvr.23.09.0208. [PMID: 38056076 DOI: 10.2460/ajvr.23.09.0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/27/2023] [Indexed: 12/08/2023]
Abstract
OBJECTIVE Design and evaluate immune responses of neonatal foals to a mRNA vaccine expressing the virulence-associated protein A (VapA) of Rhodococcus equi. ANIMALS Cultured primary equine respiratory tract cells; Serum, bronchoalveolar lavage fluid (BALF), and peripheral blood mononuclear cells (PBMCs) from 30 healthy Quarter Horse foals. METHODS VapA expression was evaluated by western immunoblot in cultured equine bronchial cells transfected with 4 mRNA constructs encoding VapA. The mRNA construct with greatest expression was used to immunize foals at ages 2 and 21 days in 5 groups: (1) 300 μg nebulized mRNA (n = 6); (2) 600 μg nebulized mRNA (n = 4); (3) 300 μg mRNA administered intramuscularly (IM) (n = 5); (4) 300 μg VapA IM (positive controls; n = 6); or (5) nebulized water (negative controls; n = 6). Serum, BALF, and PBMCs were collected at ages 3, 22, and 35 days and tested for relative anti-VapA IgG1, IgG4/7, and IgA activities using ELISA and cell-mediated immunity by ELISpot. RESULTS As formulated, nebulized mRNA was not immunogenic. However, a significant increase in anti-VapA IgG4/7 activity (P < .05) was noted exclusively in foals immunized IM with VapA mRNA by age 35 days. The proportion of foals with anti-VapA IgG1 activity > 30% of positive control differed significantly (P = .0441) between negative controls (50%; 3/6), IM mRNA foals (100%; 5/5), and IM VapA (100%; 6/6) groups. Natural exposure to virulent R equi was immunogenic in some negative control foals. CLINICAL RELEVANCE Further evaluation of the immunogenicity and efficacy of IM mRNA encoding VapA in foals is warranted.
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Affiliation(s)
- Rebecca M Legere
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Cristina Poveda
- Department of Pediatrics, Division of Tropical Medicine, Baylor College of Medicine, Houston, TX
- Texas Children's Hospital Center for Vaccine Development, Houston, TX
| | - Jeannine A Ott
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Jocelyne M Bray
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Emma G Villafone
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Bibiana Petri da Silveira
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Susanne K Kahn
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Cameron L Martin
- Department of Poultry Science, College of Agriculture & Life Sciences, Texas A&M University, College Station, TX
| | - Chiara Mancino
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston, TX
- Orthopedics and Sports Medicine, Houston Methodist Hospital, Houston, TX
| | - Francesca Taraballi
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston, TX
- Orthopedics and Sports Medicine, Houston Methodist Hospital, Houston, TX
| | - Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Luc Berghman
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
- Department of Poultry Science, College of Agriculture & Life Sciences, Texas A&M University, College Station, TX
| | - Angela I Bordin
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Jeroen Pollet
- Department of Pediatrics, Division of Tropical Medicine, Baylor College of Medicine, Houston, TX
- Texas Children's Hospital Center for Vaccine Development, Houston, TX
| | - Noah D Cohen
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
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da Silveira BP, Barhoumi R, Bray JM, Cole-Pfeiffer HM, Mabry CJ, Burghardt RC, Cohen ND, Bordin AI. Impact of surface receptors TLR2, CR3, and FcγRIII on Rhodococcus equi phagocytosis and intracellular survival in macrophages. Infect Immun 2024; 92:e0038323. [PMID: 38018994 PMCID: PMC10790823 DOI: 10.1128/iai.00383-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/26/2023] [Indexed: 11/30/2023] Open
Abstract
The virulence-associated protein A (VapA) produced by virulent Rhodococcus equi allows it to replicate in macrophages and cause pneumonia in foals. It is unknown how VapA interacts with mammalian cell receptors, but intracellular replication of avirulent R. equi lacking vapA can be restored by supplementation with recombinant VapA (rVapA). Our objectives were to determine whether the absence of the surface receptors Toll-like receptor 2 (TLR2), complement receptor 3 (CR3), or Fc gamma receptor III (FcγRIII) impacts R. equi phagocytosis and intracellular replication in macrophages, and whether rVapA restoration of virulence in R. equi is dependent upon these receptors. Wild-type (WT) murine macrophages with TLR2, CR3, or FcγRIII blocked or knocked out (KO) were infected with virulent or avirulent R. equi, with or without rVapA supplementation. Quantitative bacterial culture and immunofluorescence imaging were performed. Phagocytosis of R. equi was not affected by blockade or KO of TLR2 or CR3. Intracellular replication of virulent R. equi was not affected by TLR2, CR3, or FcγRIII blockade or KO; however, avirulent R. equi replicated in TLR2-/- and CR3-/- macrophages but not in WT and FcγRIII-/-. rVapA supplementation did not affect avirulent R. equi phagocytosis but promoted intracellular replication in WT and all KO cells. By demonstrating that TLR2 and CR3 limit replication of avirulent but not virulent R. equi and that VapA-mediated virulence is independent of TLR2, CR3, or FcγRIII, our study provides novel insights into the role of these specific surface receptors in determining the entry and intracellular fate of R. equi.
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Affiliation(s)
- Bibiana Petri da Silveira
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Jocelyne M. Bray
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Hannah M. Cole-Pfeiffer
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Cory J. Mabry
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Robert C. Burghardt
- Department of Veterinary Integrative Biosciences, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Angela I. Bordin
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
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Legere RM, Allegro AR, Affram Y, Silveira BPD, Fridley JL, Wells KM, Oezguen N, Burghardt RC, Wright GA, Pollet J, Bordin AI, Figueiredo PD, Leibowitz JL, Cohen ND. Equine bronchial epithelial cells are susceptible to cell entry with a SARS-CoV-2 pseudovirus but reveal low replication efficiency. Am J Vet Res 2023; 84:ajvr.23.06.0132. [PMID: 37442546 DOI: 10.2460/ajvr.23.06.0132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 07/02/2023] [Indexed: 07/15/2023]
Abstract
OBJECTIVE To examine the susceptibility of cultured primary equine bronchial epithelial cells (EBECs) to a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus relative to human bronchial epithelial cells (HBECs). SAMPLE Primary EBEC cultures established from healthy adult horses and commercially sourced human bronchial epithelial cells (HBECs) were used as a positive control. METHODS Angiotensin-converting enzyme 2 (ACE2) expression by EBECs was demonstrated using immunofluorescence, western immunoblot, and flow cytometry. EBECs were transduced with a lentivirus pseudotyped with the SARS-CoV-2 spike protein that binds to ACE2 and expresses the enhanced green fluorescent protein (eGFP) as a reporter. Cells were transduced with the pseudovirus at a multiplicity of infection of 0.1 for 6 hours, washed, and maintained in media for 96 hours. After 96 hours, eGFP expression in EBECs was assessed by fluorescence microscopy of cell cultures and quantitative PCR. RESULTS ACE2 expression in EBECs detected by immunofluorescence, western immunoblotting, and flow cytometry was lower in EBECs than in HBECs. After 96 hours, eGFP expression in EBECs was demonstrated by fluorescence microscopy, and mean ΔCt values from quantitative PCR were significantly (P < .0001) higher in EBECs (8.78) than HBECs (3.24) indicating lower infectivity in EBECs. CLINICAL RELEVANCE Equine respiratory tract cells were susceptible to cell entry with a SARS-CoV-2 pseudovirus. Lower replication efficiency in EBECs suggests that horses are unlikely to be an important zoonotic host of SARS-CoV-2, but viral mutations could render some strains more infective to horses. Serological and virological monitoring of horses in contact with persons shedding SARS-CoV-2 is warranted.
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Affiliation(s)
- Rebecca M Legere
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Angelica R Allegro
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Yvonne Affram
- Department of Microbial Pathogenesis & Immunology, School of Medicine, Texas A&M University, College Station, TX
| | - Bibiana Petri da Silveira
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Jennifer L Fridley
- Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Kelsey M Wells
- Department of Microbial Pathogenesis & Immunology, School of Medicine, Texas A&M University, College Station, TX
| | - Numan Oezguen
- Texas Children's Microbiome Center, Baylor College of Medicine, Houston, TX
| | - Robert C Burghardt
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Gus A Wright
- Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Jeroen Pollet
- National School of Tropical Medicine, Department of Pediatrics, Baylor College of Medicine, Houston, TX
- Texas Children's Hospital Center for Vaccine Development, Baylor College of Medicine, Houston, TX
| | - Angela I Bordin
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis & Immunology, School of Medicine, Texas A&M University, College Station, TX
- Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
| | - Julian L Leibowitz
- Department of Microbial Pathogenesis & Immunology, School of Medicine, Texas A&M University, College Station, TX
| | - Noah D Cohen
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX
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Cohen ND, Flores-Ahlschewde P, Gonzales GM, Kahn SK, da Silveira BP, Bray JM, King EE, Blair CC, Bordin AI. Fecal concentration of Rhodococcus equi determined by quantitative polymerase chain reaction of rectal swab samples to differentiate foals with pneumonia from healthy foals. J Vet Intern Med 2022; 36:1146-1151. [PMID: 35475581 PMCID: PMC9151472 DOI: 10.1111/jvim.16438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/04/2022] [Accepted: 04/12/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Diagnostic accuracy of real-time, quantitative PCR (qPCR) assays to quantify virulent Rhodococcus equi using rectal swab samples has not been systematically evaluated. OBJECTIVE To evaluate the accuracy of qPCR of rectal swab samples to differentiate foals with pneumonia from healthy foals of similar age from the same environment. ANIMALS One hundred privately owned foals born in 2021 from 2 farms in New York. METHODS An incident case-control study design was used. Rectal swabs were collected from all foals diagnosed with R. equi pneumonia at 2 horse-breeding farms (n = 47). Eligible pneumonia cases (n = 39) were matched by age to up to 2 healthy (n = 53) control foals; rectal swabs were collected from control foals on the day of diagnosis of the index case. DNA was extracted from fecal swabs and the concentration of virulent R. equi (ie, copy numbers of the virulence-associated protein A gene [vapA] per 100 ng fecal DNA) was estimated by qPCR. RESULTS The area under the ROC curve for qPCR of fecal swabs was 83.7% (95% CI, 74.9-92.6). At a threshold of 14 883 copies of vapA per 100 ng fecal DNA, specificity of the assay was 83.0% (95% CI, 71.7-92.4) and sensitivity was 79.5% (95% CI, 66.7-92.3). CONCLUSIONS AND CLINICAL IMPORTANCE Although fecal concentrations of virulent R. equi are significantly higher in pneumonic foals than healthy foals of similar age in the same environment, qPCR of rectal swabs as reported here lacks adequate diagnostic accuracy for clinical use.
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Affiliation(s)
- Noah D Cohen
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | | | - Giana M Gonzales
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Susanne K Kahn
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Bibiana Petri da Silveira
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Jocelyne M Bray
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Emily E King
- Rood & Riddle Equine Hospital in Saratoga, Saratoga Springs, New York, USA
| | - Caroline C Blair
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Angela I Bordin
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
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Cohen ND, Kahn SK, Bordin AI, Gonzales GM, da Silveira BP, Bray JM, Legere RM, Ramirez-Cortez SC. Association of pneumonia with concentrations of virulent Rhodococcus equi in fecal swabs of foals before and after intrabronchial infection with virulent R. equi. J Vet Intern Med 2022; 36:1139-1145. [PMID: 35322902 PMCID: PMC9151490 DOI: 10.1111/jvim.16409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/08/2022] [Accepted: 03/09/2022] [Indexed: 12/03/2022] Open
Abstract
Background Intragastric administration of virulent Rhodococcus equi protects foals against subsequent experimental intrabronchial (IB) infection, but it is unknown whether R. equi naturally ingested by foals contributes to their susceptibility to pneumonia. Hypothesis Fecal concentration of virulent R. equi before IB infection with R. equi is positively associated with protection from pneumonia in foals. Animals Twenty‐one university‐owned foals. Methods Samples were collected from experimental studies. Five foals were gavaged with live, virulent R. equi (LVRE) at age 2 and 4 days; the remaining 16 foals were not gavaged with LVRE (controls). Fecal swabs were collected from foals at ages 28 days, immediately before IB infection. Foals were monitored for clinical signs of pneumonia, and fecal swabs were collected approximately 2 weeks after IB infection. Swabs were tested by quantitative PCR for concentration of virulent R. equi (ie, copy numbers of the virulence‐associated protein A gene [vapA] per 100 ng fecal DNA). Results Fecal concentrations of virulent R. equi (vapA) before IB infection were significantly (P < .05) lower in control foals (25 copies/100 ng DNA [95% CI, 5 to 118 copies/100 ng DNA) that developed pneumonia (n = 8) than in healthy control foals (n = 8; 280 copies/100 ng DNA; 95% CI, 30 to 2552 copies/100 ng DNA) or those gavaged with LVRE (707 copies/100 ng DNA, 95% CI, 54 to 9207 copies/100 ng DNA). Conclusions and Clinical Importance Greater natural ingestion of LVRE might contribute to protection against pneumonia among foals.
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Affiliation(s)
- Noah D Cohen
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Susanne K Kahn
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Angela I Bordin
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Giana M Gonzales
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Bibiana Petri da Silveira
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Jocelyne M Bray
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Rebecca M Legere
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Sophia C Ramirez-Cortez
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
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Vail KJ, da Silveira BP, Bell SL, Cohen ND, Bordin AI, Patrick KL, Watson RO. The opportunistic intracellular bacterial pathogen Rhodococcus equi elicits type I interferon by engaging cytosolic DNA sensing in macrophages. PLoS Pathog 2021; 17:e1009888. [PMID: 34473814 PMCID: PMC8443056 DOI: 10.1371/journal.ppat.1009888] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/15/2021] [Accepted: 08/12/2021] [Indexed: 11/18/2022] Open
Abstract
Rhodococcus equi is a major cause of foal pneumonia and an opportunistic pathogen in immunocompromised humans. While alveolar macrophages constitute the primary replicative niche for R. equi, little is known about how intracellular R. equi is sensed by macrophages. Here, we discovered that in addition to previously characterized pro-inflammatory cytokines (e.g., Tnfa, Il6, Il1b), macrophages infected with R. equi induce a robust type I IFN response, including Ifnb and interferon-stimulated genes (ISGs), similar to the evolutionarily related pathogen, Mycobacterium tuberculosis. Follow up studies using a combination of mammalian and bacterial genetics demonstrated that induction of this type I IFN expression program is largely dependent on the cGAS/STING/TBK1 axis of the cytosolic DNA sensing pathway, suggesting that R. equi perturbs the phagosomal membrane and causes DNA release into the cytosol following phagocytosis. Consistent with this, we found that a population of ~12% of R. equi phagosomes recruits the galectin-3,-8 and -9 danger receptors. Interestingly, neither phagosomal damage nor induction of type I IFN require the R. equi’s virulence-associated plasmid. Importantly, R. equi infection of both mice and foals stimulates ISG expression, in organs (mice) and circulating monocytes (foals). By demonstrating that R. equi activates cytosolic DNA sensing in macrophages and elicits type I IFN responses in animal models, our work provides novel insights into how R. equi engages the innate immune system and furthers our understanding how this zoonotic pathogen causes inflammation and disease. Rhodococcus equi is a facultative intracellular bacterial pathogen of horses and other domestic animals, as well as an opportunistic pathogen of humans. In human patients, Rhodococcus pneumonia bears some pathological similarities to pulmonary tuberculosis, and poses a risk for misdiagnosis. In horses, R. equi infection has a major detrimental impact on the equine breeding industry due to a lack of an efficacious vaccine and its ubiquitous distribution in soil. Given the prevalence of subclinical infection and high false positive rate in current screening methods, there exists a critical need to identify factors contributing to host susceptibility. Here, we use a combination of bacterial genetics and animal models to investigate innate immune responses during R. equi infection. We found that R. equi modulates host immune sensing to elicit a type I interferon response in a manner resembling that of M. tuberculosis. We also found that the danger sensors galectin-3, -8, and -9 are recruited to a population of R. equi-containing vacuoles, independent of expression of VapA. Our research identifies innate immune sensing events and immune transcriptional signatures that may lead to biomarkers for clinical disease, more accurate screening methods, and insight into susceptibility to infection.
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Affiliation(s)
- Krystal J. Vail
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- Department of Veterinary Pathology, Texas A&M University, College Station, Texas, United States of America
| | - Bibiana Petri da Silveira
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Samantha L. Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Angela I. Bordin
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Kristin L. Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- * E-mail:
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Silveira BPD, Cohen ND, Bray JM, Barhoumi R, Bordin AI. Complement Receptor 3, but not Fcγ Receptor III, abolishes the intracellular survival advantage of virulent Rhodococcus equi in murine macrophages. The Journal of Immunology 2021. [DOI: 10.4049/jimmunol.206.supp.16.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Abstract
Complement receptor 3 (CR3) and Fc gamma receptor III (FcγRIII) are proposed to be essential for mediating Rhodococcus equi entry and killing in macrophages, respectively. Our objective was to investigate the role of each of these receptors in phagocytosis and intracellular replication of R. equi by macrophages. Wild-type (WT), CR3−/−, and FcγRIII−/− J774A.1 macrophages were infected with either virulent or avirulent opsonized R. equi. Quantitative culture was performed immediately post-infection (T0) and after 48 h (T48). Data were analyzed using mixed-effects modeling with the following outcomes: 1) ratio of inoculum:T0 (phagocytosis); and, 2) ratio of T48:T0 (intracellular survival). Additionally, WT, CR3−/−, and FcγRIII−/− macrophages were infected with virulent or avirulent GFP+ R. equi to confirm intracellular infection by confocal microscopy. Our results demonstrate that phagocytosis of either virulent or avirulent R. equi was unaffected by knocking out CR3 or FcγRIII, and imaging revealed that CR3−/− and FcγRIII−/− internalized both R. equi strains similarly to WT macrophages. As expected, intracellular survival in WT was significantly higher for virulent than avirulent R. equi. In CR3−/−, however, no significant difference in survival between virulent and avirulent strains was observed. Knocking out FcγRIII did not alter R. equi intracellular replication. Our findings demonstrate that CR3 is not necessary for R. equi infection and show that CR3 deletion eliminated the intracellular survival advantage of virulent strains. Last, FcγRIII-mediated phagocytosis does not improve intracellular killing as previously suggested.
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Gressler LT, de Vargas AC, da Costa MM, Pötter L, da Silveira BP, Sangioni LA, de Avila Botton S. Genotypic and phenotypic detection of efflux pump in Rhodococcus equi. Braz J Microbiol 2014; 45:661-5. [PMID: 25242956 PMCID: PMC4166297 DOI: 10.1590/s1517-83822014000200040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 03/14/2014] [Indexed: 11/22/2022] Open
Abstract
The req_39680 gene, associated to a putative efflux system, was detected in 60% (54/90) of R. equi isolates by PCR. The phenotypic expression of efflux mechanism was verified in 20% of the isolates using ethidium bromide. For the first time, the expression of efflux mechanism was demonstrated in R. equi.
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Affiliation(s)
- Letícia Trevisan Gressler
- Departamento de Medicina Veterinária Preventiva Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Agueda Castagna de Vargas
- Departamento de Medicina Veterinária Preventiva Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Mateus Matiuzzi da Costa
- Laboratório de Imunologia e Microbiologia Universidade Federal do Vale do São Francisco PetrolinaPE Brazil Laboratório de Imunologia e Microbiologia, Universidade Federal do Vale do São Francisco, Petrolina, PE, Brazil
| | - Luciana Pötter
- Departamento de Zootecnia Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Bibiana Petri da Silveira
- Departamento de Medicina Veterinária Preventiva Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Luis Antônio Sangioni
- Departamento de Medicina Veterinária Preventiva Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Sônia de Avila Botton
- Departamento de Medicina Veterinária Preventiva Universidade Federal de Santa Maria Santa MariaRS Brazil Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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