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Wheat WH, Chow L, Betlach AM, Pieters M, Kurihara J, Dow C, Johnson V, Garry FB, Dow S. Evaluation of Immune Nanoparticles for Rapid and Non-Specific Activation of Antiviral and Antibacterial Immune Responses in Cattle, Swine, and Poultry. Animals (Basel) 2023; 13:1686. [PMID: 37238119 PMCID: PMC10215472 DOI: 10.3390/ani13101686] [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: 03/18/2023] [Revised: 04/06/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Given the rapid potential spread of agricultural pathogens, and the lack of vaccines for many, there is an important unmet need for strategies to induce rapid and non-specific immunity against these viral and bacterial threats. One approach to the problem is to generate non-specific immune responses at mucosal surfaces to rapidly protect from entry and replication of both viral and bacterial pathogens. Using complexes of charged nanoparticle liposomes with both antiviral and antibacterial toll-like receptor (TLR) nucleic acid ligands (termed liposome-TLR complexes or LTC), we have previously demonstrated considerable induction of innate immune responses in nasal and oropharyngeal tissues and protection from viral and bacterial pathogens in mixed challenge studies in rodents, cattle, and companion animals. Therefore, in the present study, we used in vitro assays to evaluate the ability of the LTC immune stimulant to activate key innate immune pathways, particularly interferon pathways, in cattle, swine, and poultry. We found that LTC complexes induced strong production of type I interferons (IFNα and IFNβ) in both macrophages and leukocyte cultures from all three species. In addition, the LTC complexes induced the production of additional key protective cytokines (IL-6, IFNγ, and TNFα) in macrophages and leukocytes in cattle and poultry. These findings indicate that the LTC mucosal immunotherapeutic has the capability to activate key innate immune defenses in three major agricultural species and potentially induce broad protective immunity against both viral and bacterial pathogens. Additional animal challenge studies are warranted to evaluate the protective potential of LTC immunotherapy in cattle, swine, and poultry.
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Affiliation(s)
- William H. Wheat
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Lyndah Chow
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | | | - Maria Pieters
- Department of Veterinary Population Medicine, Veterinary Diagnostic Laboratory and Swine Disease Eradication Center, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55455, USA
| | - Jade Kurihara
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Cooper Dow
- Idaho State University, Pocatello, ID 83209, USA;
| | - Valerie Johnson
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA;
| | - Franklyn B. Garry
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Steven Dow
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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Lappin M, Wotman K, Chow L, Williams M, Hawley J, Dow S. Nanoparticle ocular immunotherapy for herpesvirus surface eye infections evaluated in cat infection model. PLoS One 2023; 18:e0279462. [PMID: 36607992 PMCID: PMC9821494 DOI: 10.1371/journal.pone.0279462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/07/2022] [Indexed: 01/07/2023] Open
Abstract
Ocular herpes simplex type 1 (HSV-1) infections can trigger conjunctivitis, keratitis, uveitis, and occasionally retinitis, and is a major cause of blindness worldwide. The infections are lifelong and can often recrudesce during periods of stress or immune suppression. Currently HSV-1 infections of the eye are managed primarily with anti-viral eye drops, which require frequent administration, can cause irritation, and may take weeks for full resolution of symptoms. We therefore evaluated the effectiveness of an ocular immune activating nanoparticle eye drop as a novel approach to treating HSV-1 infection, using a cat feline herpesvirus -1 (FHV-1) ocular infection model. In vitro studies demonstrated significant induction of both type I and II interferon responses by the liposome-dual TLR 3/9 agonist nanoparticles, along with suppression of FHV-1 replication. In cats with naturally occurring eye infections either proven or suspected to involve FHV-1, ocular nanoparticle treated animals experienced resolution of signs within several days of treatment, including resolution of keratitis and corneal ulcers. In a cat model of recrudescent FHV-1 infection, cats treated twice daily with immune nanoparticle eye drops experienced significant lessening of ocular signs of infection and significantly fewer episodes of viral shedding compared to control cats. Treatment was well-tolerated by all cats, without signs of drug-induced ocular irritation. We concluded therefore that non-specific ocular immunotherapy offers significant promise as a novel approach to treatment of HSV-1 and FHV-1 ocular infections.
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Affiliation(s)
- Michael Lappin
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail: (SD); (ML)
| | - Kathryn Wotman
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Lyndah Chow
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Maggie Williams
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jennifer Hawley
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Steven Dow
- From the Translational Medicine Institute, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail: (SD); (ML)
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Wheat W, Chow L, Rozo V, Herman J, Still Brooks K, Colbath A, Hunter R, Dow S. Non-specific protection from respiratory tract infections in cattle generated by intranasal administration of an innate immune stimulant. PLoS One 2020; 15:e0235422. [PMID: 32584899 PMCID: PMC7316291 DOI: 10.1371/journal.pone.0235422] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 06/15/2020] [Indexed: 12/26/2022] Open
Abstract
Alternatives to antibiotics for prevention of respiratory tract infections in cattle are urgently needed given the increasing public and regulatory pressure to reduce overall antibiotic usage. Activation of local innate immune defenses in the upper respiratory tract is one strategy to induce non-specific protection against infection with the diverse array of viral and bacterial pathogens associated with bovine respiratory disease complex (BRDC), while avoiding the use of antibiotics. Our prior studies in rodent models demonstrated that intranasal administration of liposome-TLR complexes (LTC) as a non-specific immune stimulant generated high levels of protection against lethal bacterial and viral pathogens. Therefore, we conducted studies to assess LTC induction of local immune responses and protective immunity to BRDC in cattle. In vitro, LTC were shown to activate peripheral blood mononuclear cells in cattle, which was associated with secretion of INFγ and IL-6. Macrophage activation with LTC triggered intracellular killing of Mannheimia hemolytica and several other bacterial pathogens. In studies in cattle, intranasal administration of LTC demonstrated dose-dependent activation of local innate immune responses in the nasopharynx, including recruitment of monocytes and prolonged upregulation (at least 2 weeks) of innate immune cytokine gene expression by nasopharyngeal mucosal cells. In a BRDC challenge study, intranasal administration of LTC prior to pathogen exposure resulted in significant reduction in both clinical signs of infection and disease-associated euthanasia rates. These findings indicate that intranasal administration of a non-specific innate immune stimulant can be an effective method of rapidly generating generalized protection from mixed viral and bacterial respiratory tract infections in cattle.
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Affiliation(s)
- William Wheat
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Lyndah Chow
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Vanessa Rozo
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Julia Herman
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Kelly Still Brooks
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Aimee Colbath
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Randy Hunter
- Hunter Cattle Company, Wheatland, Wyoming, United States of America
| | - Steven Dow
- Department of Clinical Sciences, From the Center for Immune and Regenerative Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
- * E-mail:
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Wheat W, Chow L, Kuzmik A, Soontararak S, Kurihara J, Lappin M, Dow S. Local immune and microbiological responses to mucosal administration of a Liposome-TLR agonist immunotherapeutic in dogs. BMC Vet Res 2019; 15:330. [PMID: 31519215 PMCID: PMC6743184 DOI: 10.1186/s12917-019-2073-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/03/2019] [Indexed: 02/08/2023] Open
Abstract
Background Non-specific immunotherapeutics have been evaluated previously in dogs, primarily for cancer treatment. However, there remains a need for a more broadly targeted, general purpose immunotherapeutic capable of activating innate immune defenses for non-specific protection or early treatment of viral and bacterial infections. To address need, our group has developed a liposomal immune stimulant (liposome-TLR complexes, LTC) containing TLR 3 and 9 agonists specifically designed to activate mucosal immune defenses in sites such as nasal cavity and oropharynx, following topical delivery. In this study, we evaluated the local immune stimulatory properties of LTC in vitro and in healthy purpose-bred dogs, including activation of cellular recruitment and cytokine production. The ability of LTC treatment to elicit effective antiviral immunity was assessed in dogs following a canine herpesvirus outbreak, and the impact of LTC treatment on the local microbiome of the oropharynx was also investigated. Results These studies revealed that LTC potently activated innate immune responses in vitro and triggered significant recruitment of inflammatory monocytes and T cells into the nasal cavity and oropharynx of healthy dogs. Administration of LTC to dogs shortly after an outbreak of canine herpesvirus infection resulted in significant reduction in clinical signs of infection. Interestingly, administration of LTC to healthy dogs did not disrupt the microbiome in the oropharynx, suggesting resiliency of the microflora to transient immune activation. Conclusions Taken together, these results indicate that LTC administration mucosally to dogs can trigger local innate immune activation and activation of antiviral immunity, without significantly disrupting the composition of the local microbiome. Thus, the LTC immune stimulant has potential for use as a non-specific immunotherapy for prevention or early treatment of viral and bacterial infections in dogs.
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Affiliation(s)
- William Wheat
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA.
| | - Lyndah Chow
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
| | - Alana Kuzmik
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
| | - Sirikul Soontararak
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
| | - Jade Kurihara
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
| | - Michael Lappin
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
| | - Steven Dow
- From the Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 80523, Ft. Collins, Colorado, CO, USA
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Contreras ET, Olea-Popelka F, Wheat W, Dow S, Hawley J, Lappin MR. Evaluation of liposome toll-like receptor ligand complexes for non-specific mucosal immunoprotection from feline herpesvirus-1 infection. J Vet Intern Med 2019; 33:831-837. [PMID: 30847973 PMCID: PMC6430869 DOI: 10.1111/jvim.15427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 01/11/2019] [Indexed: 01/08/2023] Open
Abstract
Background Feline herpesvirus‐1 (FHV‐1) infection can result in serious morbidity and mortality, especially in kittens. Immunotherapy using liposome‐toll‐like receptor (TLR) ligand complexes (LTC) has been shown to activate innate immune responses. Objectives To determine in kittens whether mucosal administration of LTC before FHV‐1 inoculation would decrease severity of clinical signs and decrease quantities of FHV‐1 DNA in materials collected on oropharyngeal swabs. Animals Nineteen, 14‐week‐old, purpose‐bred kittens. Methods Pilot clinical trial with 2 groups of kittens allocated to either an LTC or control group. The LTC were administered into both nares and the oropharynx of the 12 LTC group kittens, and all 19 kittens were inoculated with FHV‐1 24 hours later. Clinical scores were determined daily for 28 days, and oropharyngeal mucosal materials were collected every 7 days to assess FHV‐1 DNA quantities for comparison between groups. Results Conjunctivitis was more common in kittens in the control group on Days 15‐28 (P = .01) and Days 1‐28 (P = .02). Total respiratory scores were higher in the LTC group on days 15‐28 (P = .03). The LTC group had significantly decreased FHV‐1 DNA on swabs when compared to the control group on some postinoculation days, using 2 methods of calculation. Conclusions and Clinical Importance Administration of LTC to kittens was shown to decrease FHV‐1 DNA and some manifestations of illness in kittens when administrated 24 hours before inoculation, suggesting clinical benefit.
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Affiliation(s)
- Elena T Contreras
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
| | - Francisco Olea-Popelka
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
| | - William Wheat
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
| | - Steven Dow
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
| | - Jennifer Hawley
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
| | - Michael R Lappin
- Center for Companion Animal Studies and the Center for Immune and Regenerative Medicine and the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins, Colorado
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Wheat W, Chow L, Coy J, Contreras E, Lappin M, Dow S. Activation of upper respiratory tract mucosal innate immune responses in cats by liposomal toll-like receptor ligand complexes delivered topically. J Vet Intern Med 2019; 33:838-845. [PMID: 30770582 PMCID: PMC6430862 DOI: 10.1111/jvim.15426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 01/11/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Nonspecific induction of local innate immune responses by mucosally administered immunotherapy is a new approach to protection from upper respiratory tract infections. Therefore, a new liposome-toll-like receptor complex (LTC) immune stimulant was developed and investigated for its ability to activate innate immune responses in cats, both in vitro and in vivo, as part of an initial evaluation of LTC for use as an immunotherapeutic agent in cats. OBJECTIVES We hypothesized that LTC could activate innate immune responses in cats after topical application to nasal and oropharyngeal mucosal surfaces. ANIMALS Mucosal immune responses to topical administration of LTC were assessed in 7 healthy, purpose-bred cats, and in vitro responses were assessed using blood samples from healthy cats. METHODS Cytokine and cellular immune responses to LTC were evaluated in blood samples, nasal lavage specimens, and pharyngeal swabs from cats, using reverse transcriptase polymerase chain reaction assays, ELISA assays, and flow cytometry. RESULTS Liposome-TLR complexes rapidly activated leukocytes in vitro, including upregulation of costimulatory molecule expression and cytokine production. Topical administration of LTC in healthy cats triggered rapid recruitment of monocytes to the nasal and oropharyngeal mucosa. CONCLUSIONS AND CLINICAL IMPORTANCE Liposome-TLR complexes were found to effectively activate innate immune responses in cats after mucosal administration. These findings suggest that LTC have potential for use as a new mucosally administered immunotherapy for nonspecific protection from viral and bacterial respiratory tract infections.
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Affiliation(s)
- William Wheat
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Lyndah Chow
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Jonathan Coy
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Elena Contreras
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Michael Lappin
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Steven Dow
- Center for Immune and Regenerative Medicine and the Center for Companion Animal Studies, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
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Skyberg JA, Lacey CA. Hematopoietic MyD88 and IL-18 are essential for IFN-γ-dependent restriction of type A Francisella tularensis infection. J Leukoc Biol 2017; 102:1441-1450. [PMID: 28951422 DOI: 10.1189/jlb.4a0517-179r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/03/2017] [Accepted: 08/29/2017] [Indexed: 12/11/2022] Open
Abstract
Francisella tularensis is a highly infectious intracellular bacterium that causes the potentially fatal disease tularemia. We used mice with conditional MyD88 deficiencies to investigate cellular and molecular mechanisms by which MyD88 restricts type A F. tularensis infection. F. tularensis-induced weight loss was predominately dependent on MyD88 signaling in nonhematopoietic cells. In contrast, MyD88 signaling in hematopoietic cells, but not in myeloid and dendritic cells, was essential for control of F. tularensis infection in tissue. Myeloid and dendritic cell MyD88 deficiency also did not markedly impair cytokine production during infection. Although the production of IL-12 or -18 was not significantly reduced in hematopoietic MyD88-deficient mice, IFN-γ production was abolished in these animals. In addition, neutralization studies revealed that control of F. tularensis infection mediated by hematopoietic MyD88 was entirely dependent on IFN-γ. Although IL-18 production was not significantly affected by MyD88 deficiency, IL-18 was essential for IFN-γ production and restricted bacterial replication in an IFN-γ-dependent manner. Caspase-1 was also found to be partially necessary for the production of IL-18 and IFN-γ and for control of F. tularensis replication. Our collective data show that the response of leukocytes to caspase-1-dependent IL-18 via MyD88 is critical, whereas MyD88 signaling in myeloid and dendritic cells is dispensable for IFN-γ-dependent control of type A F. tularensis infection.
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Affiliation(s)
- Jerod A Skyberg
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA; and .,Laboratory for Infectious Disease Research, University of Missouri, Columbia, Missouri, USA
| | - Carolyn A Lacey
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA; and.,Laboratory for Infectious Disease Research, University of Missouri, Columbia, Missouri, USA
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Rico AB, Phillips AT, Schountz T, Jarvis DL, Tjalkens RB, Powers AM, Olson KE. Venezuelan and western equine encephalitis virus E1 liposome antigen nucleic acid complexes protect mice from lethal challenge with multiple alphaviruses. Virology 2016; 499:30-39. [PMID: 27632563 DOI: 10.1016/j.virol.2016.08.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 08/24/2016] [Accepted: 08/25/2016] [Indexed: 10/21/2022]
Abstract
Eastern, Venezuelan and western equine encephalitis viruses (EEEV, VEEV, and WEEV) are mosquito-borne viruses that cause substantial disease in humans and other vertebrates. Vaccines are limited and current treatment options have not proven successful. In this report, we vaccinated outbred mice with lipid-antigen-nucleic acid-complexes (LANACs) containing VEEV E1+WEEV E1 antigen and characterized protective efficacy against lethal EEEV, VEEV, and WEEV challenge. Vaccination resulted in complete protection against EEEV, VEEV, and WEEV in CD-1 mice. Measurements of bioluminescence and plaque reduction neutralization tests (PRNTs) indicate that LANAC VEEV E1+WEEV E1 vaccination is sterilizing against VEEV and WEEV challenge; whereas immunity to EEEV is not sterilizing. Passive transfer of rabbit VEEV E1+WEEV E1 immune serum to naive mice extended the mean time to death (MTD) of EEEV challenged mice and provided significant protection from lethal VEEV and WEEV challenge.
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Affiliation(s)
- Amber B Rico
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA.
| | - Aaron T Phillips
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Tony Schountz
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Donald L Jarvis
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
| | - Ronald B Tjalkens
- Department of Environmental & Radiological Health Sciences, CSU, Fort Collins, CO, USA
| | - Ann M Powers
- Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | - Ken E Olson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
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Levast B, Awate S, Babiuk L, Mutwiri G, Gerdts V, van Drunen Littel-van den Hurk S. Vaccine Potentiation by Combination Adjuvants. Vaccines (Basel) 2014; 2:297-322. [PMID: 26344621 PMCID: PMC4494260 DOI: 10.3390/vaccines2020297] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/22/2014] [Accepted: 03/28/2014] [Indexed: 01/02/2023] Open
Abstract
Adjuvants are crucial components of vaccines. They significantly improve vaccine efficacy by modulating, enhancing, or extending the immune response and at the same time reducing the amount of antigen needed. In contrast to previously licensed adjuvants, current successful adjuvant formulations often consist of several molecules, that when combined, act synergistically by activating a variety of immune mechanisms. These "combination adjuvants" are already registered with several vaccines, both in humans and animals, and novel combination adjuvants are in the pipeline. With improved knowledge of the type of immune responses needed to successfully induce disease protection by vaccination, combination adjuvants are particularly suited to not only enhance, but also direct the immune responses desired to be either Th1-, Th2- or Th17-biased. Indeed, in view of the variety of disease and population targets for vaccine development, a panel of adjuvants will be needed to address different disease targets and populations. Here, we will review well-known and new combination adjuvants already licensed or currently in development-including ISCOMs, liposomes, Adjuvant Systems Montanides, and triple adjuvant combinations-and summarize their performance in preclinical and clinical trials. Several of these combination adjuvants are promising having promoted improved and balanced immune responses.
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Affiliation(s)
- Benoît Levast
- VIDO-Intervac, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
| | - Sunita Awate
- VIDO-Intervac, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
| | - Lorne Babiuk
- University Hall, University of Alberta, Edmonton, AB T6G 2J9, Canada.
| | - George Mutwiri
- VIDO-Intervac, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
- School of Public Health, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada.
| | - Volker Gerdts
- VIDO-Intervac, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
- Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada.
| | - Sylvia van Drunen Littel-van den Hurk
- VIDO-Intervac, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
- Microbiology and Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada.
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Abstract
Francisella tularensis is a gram-negative bacterium that causes the zoonotic disease tularemia. Francisella is highly infectious via the respiratory route (~10 CFUs) and pulmonary infections due to type A strains of F. tularensis are highly lethal in untreated patients (>30%). In addition, no vaccines are licensed to prevent tularemia in humans. Due to the high infectivity and mortality of pulmonary tularemia, F. tularensis has been weaponized, including via the introduction of antibiotic resistance, by several countries. Because of the lack of efficacious vaccines, and concerns about F. tularensis acquiring resistance to antibiotics via natural or illicit means, augmentation of host immunity, and humoral immunotherapy have been investigated as countermeasures against tularemia. This manuscript will review advances made and challenges in the field of immunotherapy against tularemia.
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Affiliation(s)
- Jerod A Skyberg
- Department of Veterinary Pathobiology and Laboratory for Infectious Disease Research; University of Missouri; Columbia, MO USA
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Interleukin-17 protects against the Francisella tularensis live vaccine strain but not against a virulent F. tularensis type A strain. Infect Immun 2013; 81:3099-105. [PMID: 23774604 DOI: 10.1128/iai.00203-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Francisella tularensis is a highly infectious intracellular bacterium that causes the zoonotic infection tularemia. While much literature exists on the host response to F. tularensis infection, the vast majority of work has been conducted using attenuated strains of Francisella that do not cause disease in humans. However, emerging data indicate that the protective immune response against attenuated F. tularensis versus F. tularensis type A differs. Several groups have recently reported that interleukin-17 (IL-17) confers protection against the live vaccine strain (LVS) of Francisella. While we too have found that IL-17Rα(-/-) mice are more susceptible to F. tularensis LVS infection, our studies, using a virulent type A strain of F. tularensis (SchuS4), indicate that IL-17Rα(-/-) mice display organ burdens and pulmonary gamma interferon (IFN-γ) responses similar to those of wild-type mice following infection. In addition, oral LVS vaccination conferred equivalent protection against pulmonary challenge with SchuS4 in both IL-17Rα(-/-) and wild-type mice. While IFN-γ was found to be critically important for survival in a convalescent model of SchuS4 infection, IL-17 neutralization from either wild-type or IFN-γ(-/-) mice had no effect on morbidity or mortality in this model. IL-17 protein levels were also higher in the lungs of mice infected with the LVS rather than F. tularensis type A, while IL-23p19 mRNA expression was found to be caspase-1 dependent in macrophages infected with LVS but not SchuS4. Collectively, these results demonstrate that IL-17 is dispensable for host immunity to type A F. tularensis infection, and that induced and protective immunity differs between attenuated and virulent strains of F. tularensis.
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Role of NK cells in host defense against pulmonary type A Francisella tularensis infection. Microbes Infect 2012; 15:201-11. [PMID: 23211929 DOI: 10.1016/j.micinf.2012.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/25/2012] [Accepted: 11/15/2012] [Indexed: 01/16/2023]
Abstract
Pneumonic tularemia is a potentially fatal disease caused by the Category A bioterrorism agent Francisella tularensis. Understanding the pulmonary immune response to this bacterium is necessary for developing effective vaccines and therapeutics. In this study, characterization of immune cell populations in the lungs of mice infected with the type A strain Schu S4 revealed a significant loss in natural killer (NK) cells over time. Since this decline in NK cells correlated with morbidity and mortality, we hypothesized these cells contribute to host defense against Schu S4 infection. Depletion of NK cells prior to Schu S4 challenge significantly reduced IFN-γ and granzyme B in the lung but had no effect on bacterial burden or disease progression. Conversely, increasing NK cell numbers with the anti-apoptotic cytokine IL-15 and soluble receptor IL-15Rα had no significant impact on Schu S4 growth in vivo. A modest decrease in median time to death, however, was observed in live vaccine strain (LVS)-vaccinated mice depleted of NK1.1+ cells and challenged with Schu S4. Therefore, NK cells do not appear to contribute to host defense against acute respiratory infection with type A F. tularensis in vivo, but they play a minor role in protection elicited by LVS vaccination.
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Skyberg JA, Rollins MF, Holderness JS, Marlenee NL, Schepetkin IA, Goodyear A, Dow SW, Jutila MA, Pascual DW. Nasal Acai polysaccharides potentiate innate immunity to protect against pulmonary Francisella tularensis and Burkholderia pseudomallei Infections. PLoS Pathog 2012; 8:e1002587. [PMID: 22438809 PMCID: PMC3305411 DOI: 10.1371/journal.ppat.1002587] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 01/30/2012] [Indexed: 01/28/2023] Open
Abstract
Pulmonary Francisella tularensis and Burkholderia pseudomallei infections are highly lethal in untreated patients, and current antibiotic regimens are not always effective. Activating the innate immune system provides an alternative means of treating infection and can also complement antibiotic therapies. Several natural agonists were screened for their ability to enhance host resistance to infection, and polysaccharides derived from the Acai berry (Acai PS) were found to have potent abilities as an immunotherapeutic to treat F. tularensis and B. pseudomallei infections. In vitro, Acai PS impaired replication of Francisella in primary human macrophages co-cultured with autologous NK cells via augmentation of NK cell IFN-γ. Furthermore, Acai PS administered nasally before or after infection protected mice against type A F. tularensis aerosol challenge with survival rates up to 80%, and protection was still observed, albeit reduced, when mice were treated two days post-infection. Nasal Acai PS administration augmented intracellular expression of IFN-γ by NK cells in the lungs of F. tularensis-infected mice, and neutralization of IFN-γ ablated the protective effect of Acai PS. Likewise, nasal Acai PS treatment conferred protection against pulmonary infection with B. pseudomallei strain 1026b. Acai PS dramatically reduced the replication of B. pseudomallei in the lung and blocked bacterial dissemination to the spleen and liver. Nasal administration of Acai PS enhanced IFN-γ responses by NK and γδ T cells in the lungs, while neutralization of IFN-γ totally abrogated the protective effect of Acai PS against pulmonary B. pseudomallei infection. Collectively, these results demonstrate Acai PS is a potent innate immune agonist that can resolve F. tularensis and B. pseudomallei infections, suggesting this innate immune agonist has broad-spectrum activity against virulent intracellular pathogens.
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Affiliation(s)
- Jerod A Skyberg
- Department of Immunology and Infectious Diseases, Montana State University, Bozeman, Montana, USA.
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Antibacterial role for natural killer cells in host defense to Bacillus anthracis. Infect Immun 2011; 80:234-42. [PMID: 22006566 DOI: 10.1128/iai.05439-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural killer (NK) cells have innate antibacterial activity that could be targeted for clinical interventions for infectious disease caused by naturally occurring or weaponized bacterial pathogens. To determine a potential role for NK cells in immunity to Bacillus anthracis, we utilized primary human and murine NK cells, in vitro assays, and in vivo NK cell depletion in a murine model of inhalational anthrax. Our results demonstrate potent antibacterial activity by human NK cells against B. anthracis bacilli within infected autologous monocytes. Surprisingly, NK cells also mediate moderate antibacterial effects on extracellular vegetative bacilli but do not have activity against extracellular or intracellular spores. The immunosuppressive anthrax lethal toxin impairs NK gamma interferon (IFN-γ) expression, but neither lethal nor edema toxin significantly alters the viability or cytotoxic effector function of NK cells. Compared to human NK cells, murine NK cells have a similar, though less potent, activity against intracellular and extracellular B. anthracis. The in vivo depletion of murine NK cells does not alter animal survival following intranasal infection with B. anthracis spores in our studies but significantly increases the bacterial load in the blood of infected animals. Our studies demonstrate that NK cells participate in the innate immune response against B. anthracis and suggest that immune modulation to augment NK cell function in early stages of anthrax should be further explored in animal models as a clinical intervention strategy.
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Christensen D, Korsholm KS, Andersen P, Agger EM. Cationic liposomes as vaccine adjuvants. Expert Rev Vaccines 2011; 10:513-21. [PMID: 21506648 DOI: 10.1586/erv.11.17] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The application of cationic liposomes as vaccine delivery systems and adjuvants has been investigated extensively over the last few decades. However, cationic liposomes are, in general, not sufficiently immunostimulatory, which is why the combination of liposomes with immunostimulating ligands has arisen as a strategy in the development of novel adjuvant systems. Within the last 5 years, two novel adjuvant systems based on cationic liposomes incorporating Toll-like receptor or non-Toll-like receptor immunostimulating ligands have progressed from preclinical testing in smaller animal species to clinical testing in humans. The immune responses that these clinical candidates induce are primarily of the Th1 type for which there is a profound unmet need. Furthermore, a number of new cationic liposome-forming surfactants with notable immunostimulatory properties have been discovered. In this article we review the recent progress on the application of cationic liposomes as vaccine delivery systems/adjuvants.
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Affiliation(s)
- Dennis Christensen
- Statens Serum Institut, Department of Infectious Disease Immunology, Copenhagen, Denmark.
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Mucosal immunization with liposome-nucleic acid adjuvants generates effective humoral and cellular immunity. Vaccine 2011; 29:5304-12. [PMID: 21600950 DOI: 10.1016/j.vaccine.2011.05.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/15/2011] [Accepted: 05/05/2011] [Indexed: 01/07/2023]
Abstract
Development of effective new mucosal vaccine adjuvants has become a priority with the increase in emerging viral and bacterial pathogens. We previously reported that cationic liposomes complexed with non-coding plasmid DNA (CLDC) were effective parenteral vaccine adjuvants. However, little is known regarding the ability of liposome-nucleic acid complexes to function as mucosal vaccine adjuvants, or the nature of the mucosal immune responses elicited by mucosal liposome-nucleic acid adjuvants. To address these questions, antibody and T cell responses were assessed in mice following intranasal immunization with CLDC-adjuvanted vaccines. The effects of CLDC adjuvant on antigen uptake, trafficking, and cytokine responses in the airways and draining lymph nodes were also assessed. We found that mucosal immunization with CLDC-adjuvanted vaccines effectively generated potent mucosal IgA antibody responses, as well as systemic IgG responses. Notably, mucosal immunization with CLDC adjuvant was very effective in generating strong and sustained antigen-specific CD8(+) T cell responses in the airways of mice. Mucosal administration of CLDC vaccines also induced efficient uptake of antigen by DCs within the mediastinal lymph nodes. Finally, a killed bacterial vaccine adjuvanted with CLDC induced significant protection from lethal pulmonary challenge with Burkholderia pseudomallei. These findings suggest that liposome-nucleic acid adjuvants represent a promising new class of mucosal adjuvants for non-replicating vaccines, with notable efficiency at eliciting both humoral and cellular immune responses following intranasal administration.
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Henriksen-Lacey M, Korsholm KS, Andersen P, Perrie Y, Christensen D. Liposomal vaccine delivery systems. Expert Opin Drug Deliv 2011; 8:505-19. [DOI: 10.1517/17425247.2011.558081] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Stundick MV, Metz M, Sampath A, Larsen JC. State-of-the-art therapeutic medical countermeasures for bacterial threat agents. Drug Dev Res 2011. [DOI: 10.1002/ddr.20462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Genetic identification of unique immunological responses in mice infected with virulent and attenuated Francisella tularensis. Microbes Infect 2010; 13:261-75. [PMID: 21070859 DOI: 10.1016/j.micinf.2010.10.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 10/27/2010] [Accepted: 10/29/2010] [Indexed: 11/22/2022]
Abstract
Francisella tularensis is a category A select agent based on its infectivity and virulence but disease mechanisms in infection remain poorly understood. Murine pulmonary models of infection were therefore employed to assess and compare dissemination and pathology and to elucidate the host immune response to infection with the highly virulent Type A F. tularensis strain Schu4 versus the less virulent Type B live vaccine strain (LVS). We found that dissemination and pathology in the spleen was significantly greater in mice infected with F. tularensis Schu4 compared to mice infected with F. tularensis LVS. Using gene expression profiling to compare the response to infection with the two F. tularensis strains, we found that there were significant differences in the expression of genes involved in the apoptosis pathway, antigen processing and presentation pathways, and inflammatory response pathways in mice infected with Schu4 when compared to LVS. These transcriptional differences coincided with marked differences in dissemination and severity of organ lesions in mice infected with the Schu4 and LVS strains. Therefore, these findings indicate that altered apoptosis, antigen presentation and production of inflammatory mediators explain the differences in pathogenicity of F. tularensis Schu4 and LVS.
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Ireland R, Olivares-Zavaleta N, Warawa JM, Gherardini FC, Jarrett C, Hinnebusch BJ, Belisle JT, Fairman J, Bosio CM. Effective, broad spectrum control of virulent bacterial infections using cationic DNA liposome complexes combined with bacterial antigens. PLoS Pathog 2010; 6:e1000921. [PMID: 20523903 PMCID: PMC2877747 DOI: 10.1371/journal.ppat.1000921] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 04/23/2010] [Indexed: 12/26/2022] Open
Abstract
Protection against virulent pathogens that cause acute, fatal disease is often hampered by development of microbial resistance to traditional chemotherapeutics. Further, most successful pathogens possess an array of immune evasion strategies to avoid detection and elimination by the host. Development of novel, immunomodulatory prophylaxes that target the host immune system, rather than the invading microbe, could serve as effective alternatives to traditional chemotherapies. Here we describe the development and mechanism of a novel pan-anti-bacterial prophylaxis. Using cationic liposome non-coding DNA complexes (CLDC) mixed with crude F. tularensis membrane protein fractions (MPF), we demonstrate control of virulent F. tularensis infection in vitro and in vivo. CLDC+MPF inhibited bacterial replication in primary human and murine macrophages in vitro. Control of infection in macrophages was mediated by both reactive nitrogen species (RNS) and reactive oxygen species (ROS) in mouse cells, and ROS in human cells. Importantly, mice treated with CLDC+MPF 3 days prior to challenge survived lethal intranasal infection with virulent F. tularensis. Similarly to in vitro observations, in vivo protection was dependent on the presence of RNS and ROS. Lastly, CLDC+MPF was also effective at controlling infections with Yersinia pestis, Burkholderia pseudomallei and Brucella abortus. Thus, CLDC+MPF represents a novel prophylaxis to protect against multiple, highly virulent pathogens. Conventional treatment of bacterial infections typically includes administration of antibiotics. However, many pathogens have developed spontaneous resistance to commonly used antibiotics. Development of new compounds that stimulate the host immune system to directly kill bacteria by mechanisms different from those utilized by antibiotics may serve as effective alternatives to antibiotic therapy. In this report, we describe a novel compound capable of controlling infections mediated by different, unrelated bacteria via the induction of host derived reactive oxygen and reactive nitrogen species. This compound is comprised of cationic liposome DNA complexes (CLDC) and crude membrane preparations (MPF) obtained from attenuated Francisella tularensis Live Vaccine Strain (LVS). Pretreatment of primary mouse or human cells limited replication of virulent F. tularensis, Burkholderia pseudomallei, Yersinia pestis and Brucella abortus in vitro. CLDC+MPF was also effective for controlling lethal pulmonary infections with virulent F. tularensis. Thus, CLDC+MPF represents a novel antimicrobial for treatment of lethal, acute, bacterial infections.
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Affiliation(s)
- Robin Ireland
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Norma Olivares-Zavaleta
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Jonathan M. Warawa
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Frank C. Gherardini
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Clayton Jarrett
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - B. Joseph Hinnebusch
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - John T. Belisle
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jeffery Fairman
- Juvaris Biotherapeutics, Burlingame, California, United States of America
| | - Catharine M. Bosio
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
- * E-mail:
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Immunotherapy markedly increases the effectiveness of antimicrobial therapy for treatment of Burkholderia pseudomallei infection. Antimicrob Agents Chemother 2010; 54:1785-92. [PMID: 20176901 DOI: 10.1128/aac.01513-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Burkholderia pseudomallei is a soil bacterium that is endemic in southeast Asia and northern Australia and that can cause both acutely lethal pneumonia and chronic systemic infections in humans. The effective treatment of infection with B. pseudomallei requires rapid diagnosis and prolonged treatment with high doses of antimicrobials, and even with appropriate antibiotic therapy, patient relapses are common. Thus, new approaches to the treatment of B. pseudomallei infections are needed. In the present study, we asked whether active immunotherapy with gamma interferon (IFN-gamma), a key cytokine regulating the intracellular replication of B. pseudomallei, could increase the effectiveness of conventional antimicrobial therapy for B. pseudomallei infection. Macrophage infection assays and in vivo pulmonary challenge models were used to assess the inhibitory effects of combined treatment with IFN-gamma and ceftazidime on B. pseudomallei infection. We found that treatment with even very low doses of IFN-gamma and ceftazidime elicited strong synergistic inhibition of B. pseudomallei growth within infected macrophages. In vivo, active immunotherapy markedly potentiated the effectiveness of low-dose ceftazidime therapy for the treatment of infected mice in a pulmonary challenge model of B. pseudomallei. Combined treatment was associated with a significant reduction in the bacterial burden and a significant lessening of bacterial dissemination. We concluded, therefore, that immunotherapy with either endogenous or exogenous IFN-gamma could significantly increase the effectiveness of conventional antimicrobial therapy for the treatment of acute B. pseudomallei infection.
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Oyston PCF. Francisella tularensis vaccines. Vaccine 2009; 27 Suppl 4:D48-51. [PMID: 19837286 DOI: 10.1016/j.vaccine.2009.07.090] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 07/24/2009] [Indexed: 12/12/2022]
Abstract
Francisella tularensis has attracted attention historically as a biological weapon, due to its high infectivity in aerosols, and the severity of disease in humans. There is no licensed vaccine currently available, although an attenuated live vaccine strain (LVS) was identified in the middle of the last century and has been successfully used to protect humans. Efforts are underway to determine the basis of attenuation of LVS, and to understand the immunity required for protection. Alternative approaches to produce subunit vaccines and defined attenuated strains are also in progress. However, the limitations of animal models may make licensing a candidate vaccine challenging.
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Affiliation(s)
- Petra C F Oyston
- Biomedical Sciences, Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, UK.
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