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Hidalgo-Gajardo A, Gutiérrez N, Lamazares E, Espinoza F, Escobar-Riquelme F, Leiva MJ, Villavicencio C, Mena-Ulecia K, Montesino R, Altamirano C, Sánchez O, Rivas CI, Ruíz Á, Toledo JR. Co-Formulation of Recombinant Porcine IL-18 Enhances the Onset of Immune Response in a New Lawsonia intracellularis Vaccine. Vaccines (Basel) 2023; 11:1788. [PMID: 38140192 PMCID: PMC10747595 DOI: 10.3390/vaccines11121788] [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: 10/17/2023] [Revised: 11/20/2023] [Accepted: 11/25/2023] [Indexed: 12/24/2023] Open
Abstract
Pig is one of the most consumed meats worldwide. One of the main conditions for pig production is Porcine Enteropathy caused by Lawsonia intracellularis. Among the effects of this disease is chronic mild diarrhea, which affects the weight gain of pigs, generating economic losses. Vaccines available to prevent this condition do not have the desired effect, but this limitation can be overcome using adjuvants. Pro-inflammatory cytokines, such as interleukin 18 (IL-18), can improve an immune response, reducing the immune window of protection. In this study, recombinant porcine IL-18 was produced and expressed in Escherichia coli and Pichia pastoris. The protein's biological activity was assessed in vitro and in vivo, and we determined that the P. pastoris protein had better immunostimulatory activity. A vaccine candidate against L. intracellularis, formulated with and without IL-18, was used to determine the pigs' cellular and humoral immune responses. Animals injected with the candidate vaccine co-formulated with IL-18 showed a significant increase of Th1 immune response markers and an earlier increase of antibodies than those vaccinated without the cytokine. This suggests that IL-18 acts as an immunostimulant and vaccine adjuvant to boost the immune response against the antigens, reducing the therapeutic window of recombinant protein-based vaccines.
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Affiliation(s)
- Angela Hidalgo-Gajardo
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
- Centro de Desarrollo e Innovación Biovacuvet SpA, VIII Región, Concepción 4090838, Chile
| | - Nicolás Gutiérrez
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
- Centro de Desarrollo e Innovación Biovacuvet SpA, VIII Región, Concepción 4090838, Chile
| | - Emilio Lamazares
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Felipe Espinoza
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
- Centro de Desarrollo e Innovación Biovacuvet SpA, VIII Región, Concepción 4090838, Chile
| | - Fernanda Escobar-Riquelme
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - María J. Leiva
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Carla Villavicencio
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Karel Mena-Ulecia
- Departamento de Ciencias Biológicas y Químicas, Facultad de Recursos Naturales, Universidad Católica de Temuco, IX Región, Temuco 4813302, Chile;
| | - Raquel Montesino
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Claudia Altamirano
- Laboratorio de Cultivos Celulares, Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, V Región, Valparaíso 2362803, Chile;
| | - Oliberto Sánchez
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Coralia I. Rivas
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
| | - Álvaro Ruíz
- Departamento de Patología y Medicina Preventiva, Facultad de Ciencias Veterinarias, Universidad de Concepción, XVI Región, Chillán 3812120, Chile;
| | - Jorge R. Toledo
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, VIII Región, Concepción 4070386, Chile; (A.H.-G.); (M.J.L.); (C.V.); (C.I.R.)
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Song K, Yu JY, Li J, Li M, Peng LY, Yi PF. Astragaloside IV Regulates cGAS-STING Signaling Pathway to Alleviate Immunosuppression Caused by PRRSV Infection. Viruses 2023; 15:1586. [PMID: 37515271 PMCID: PMC10383485 DOI: 10.3390/v15071586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/01/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) poses a global threat to pig health and results in significant economic losses. Impaired innate and adaptive immune responses are evident during PRRSV infection. Cyclic GMP-AMP synthase (cGAS), a classical pattern recognition receptor recognizing mainly intracytoplasmic DNA, induces type I IFN responses through the cGAS-STING signaling pathway. It has also been demonstrated that cGAS-STING is involved in PRRSV infection. This study utilized the qRT-PCR, ELISA, and WB methods to examine the effects of Astragaloside IV (AS-IV) on the regulation of innate immune function and cGAS-STING signaling pathway in porcine alveolar macrophages. The results showed that AS-IV attenuated the decreased innate immune function caused by PRRSV infection, restored the inhibited cGAS-STING signaling pathway, and increased the expression of interferon, ultimately exerting antiviral effects. Moreover, these results suggest that AS-IV may be a promising candidate for a new anti-PRRSV antiviral, and its mechanism of action may provide insights for developing novel antiviral agents.
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Affiliation(s)
- Ke Song
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Jia-Ying Yu
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Jiang Li
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Miao Li
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Lu-Yuan Peng
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Peng-Fei Yi
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
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Arakelian T, Oosterhuis K, Tondini E, Los M, Vree J, van Geldorp M, Camps M, Teunisse B, Zoutendijk I, Arens R, Zondag G, Ossendorp F, van Bergen J. Pyroptosis-inducing active caspase-1 as a genetic adjuvant in anti-cancer DNA vaccination. Vaccine 2022; 40:2087-2098. [PMID: 35177300 DOI: 10.1016/j.vaccine.2022.02.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 01/10/2022] [Accepted: 02/04/2022] [Indexed: 12/28/2022]
Abstract
Pyroptosis is a recently discovered form of inflammatory programmed necrosis characterized by caspase-1-mediated and gasdermin D-dependent cell death leading to the release of pro-inflammatory cytokines such as Interleukin-1 beta (IL-1β). Here, we evaluated whether pyroptosis could be exploited in DNA vaccination by incorporating a constitutively active variant of caspase-1 to the antigen-expressing DNA. In vitro, transfection with constitutively active caspase-1 DNA induced pro-IL-1β maturation and IL-1β release as well as gasdermin D-dependent cell death. To test active caspase-1 as a genetic adjuvant for the induction of antigen-specific T cell responses, mice were vaccinated intradermally with a DNA vaccine consisting of the active caspase-1 plasmid together with a plasmid encoding an ovalbumin-derived CD8 T cell epitope. Active caspase-1 accelerated and amplified antigen-specific CD8 T cell responses when administered simultaneously with the DNA vaccine at an equimolar dose. Moreover, upon challenge with melanoma cells expressing ovalbumin, mice vaccinated with the antigen vaccine adjuvanted with active caspase-1 showed significantly better survival compared to the non-adjuvanted group. In conclusion, we have developed a novel genetic adjuvant that for the first time employs the pyroptosis pathway to improve DNA vaccination against cancer.
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Affiliation(s)
- Tsolere Arakelian
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Koen Oosterhuis
- Immunetune BV, Leiden, the Netherlands; Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Elena Tondini
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Mandy Los
- Immunetune BV, Leiden, the Netherlands
| | - Jana Vree
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Mariska van Geldorp
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Marcel Camps
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | | | | | - Ramon Arens
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Gerben Zondag
- Immunetune BV, Leiden, the Netherlands; Synvolux Therapeutics BV, Leiden, the Netherlands
| | - Ferry Ossendorp
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands.
| | - Jeroen van Bergen
- Immunetune BV, Leiden, the Netherlands; Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands.
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Phenotypic Characterization of Porcine IFNγ-Producing Lymphocytes in Porcine Reproductive and Respiratory Syndrome Virus Vaccinated and Challenged Pigs. Virol Sin 2018; 33:524-530. [PMID: 30560415 DOI: 10.1007/s12250-018-0073-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 11/07/2018] [Indexed: 12/30/2022] Open
Abstract
Porcine reproductive and respiratory syndrome (PRRS) continues to be one of the most important swine diseases worldwide. Interferon-γ (IFNγ)-mediated type I cell-mediated immune response plays an important role in protection from, and clearance of, PRRS virus (PRRSV). Several lymphocyte subsets including T-helper, CTLs, Th/memory cells, and γδ T lymphocytes were previously reported to produce IFNγ during PRRSV infection. However, the proportion and phenotypic characterization of these IFNγ-secreting lymphocytes have not been explored. In this study, IFNγ producted by different lymphocyte subsets was assessed by multi-color flow cytometry after vaccination with PRRSV modified live vaccine (PRRSV-MLV) and challenge with homogeneous or heterogeneous PRRSV. The results showed that T-helper cells were the major IFNγ-secreting cell population after PRRSV-MLV vaccination and PRRSV challenge. Additionally, the proportion of IFNγ producing Th/memory cells and γδ T cells increased after PRRSV challenge. This difference was accounted for an enhanced ability to produce IFNγ in Th/memory cells and an enlarged quantity of γδ T cells. The results presented here could contribute to our understanding of the roles of IFNγ in protective immunity against PRRSV infection and may be useful for assessment of cell-mediated immunity in vaccine tests.
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Renukaradhya GJ, Meng XJ, Calvert JG, Roof M, Lager KM. Inactivated and subunit vaccines against porcine reproductive and respiratory syndrome: Current status and future direction. Vaccine 2015; 33:3065-72. [PMID: 25980425 DOI: 10.1016/j.vaccine.2015.04.102] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/18/2015] [Accepted: 04/30/2015] [Indexed: 02/07/2023]
Abstract
Within a few years of its emergence in the late 1980s, the PRRS virus had spread globally to become the foremost infectious disease concern for the pork industry. Since 1994, modified live-attenuated vaccines against porcine reproductive and respiratory syndrome virus (PRRSV-MLV) have been widely used, but have failed to provide complete protection against emerging and heterologous field strains of the virus. Moreover, like many other MLVs, PRRSV-MLVs have safety concerns including vertical and horizontal transmission of the vaccine virus and several documented incidences of reversion to virulence. Thus, the development of efficacious inactivated vaccines is warranted for the control and eradication of PRRS. Since the early 1990s, researchers have been attempting to develop inactivated PRRSV vaccines, but most of the candidates have failed to elicit protective immunity even against homologous virus challenge. Recent research findings relating to both inactivated and subunit candidate PRRSV vaccines have shown promise, but they need to be pursued further to improve their heterologous efficacy and cost-effectiveness before considering commercialization. In this comprehensive review, we provide information on attempts to develop PRRSV inactivated and subunit vaccines. These includes various virus inactivation strategies, adjuvants, nanoparticle-based vaccine delivery systems, DNA vaccines, and recombinant subunit vaccines produced using baculovirus, plant, and replication-deficient viruses as vector vaccines. Finally, future directions for the development of innovative non-infectious PRRSV vaccines are suggested. Undoubtedly there remains a need for novel PRRSV vaccine strategies targeted to deliver cross-protective, non-infectious vaccines for the control and eradication of PRRS.
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Affiliation(s)
- Gourapura J Renukaradhya
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States.
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | | | - Michael Roof
- Boehringer Ingelheim Vetmedica, Inc., Ames, IA, United States
| | - Kelly M Lager
- Virology Swine Research Unit, National Animal Disease Center, U.S. Department of Agriculture, Ames, IA, United States.
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Yang M, Xiang Q, Zhang X, Li X, Sylla S, Ding Z. RNA interference targeting nucleocapsid protein inhibits porcine reproductive and respiratory syndrome virus replication in Marc-145 cells. J Microbiol 2014; 52:333-9. [PMID: 24682995 PMCID: PMC7090845 DOI: 10.1007/s12275-014-3419-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 01/28/2014] [Accepted: 03/12/2014] [Indexed: 01/16/2023]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is an important disease, which leads to severe economic losses in swine-producing areas of the world. However, current antiviral strategies cannot provide highly effective protection. In this study, three theoretically effective interference target sites (71–91, 144–164, 218–238) targeting the nucleocapsid (N) gene of PRRSV were designed and selected, and then three siRNA-expressing plasmids were constructed, respectively named p2.1-N71, p2.1-N144, and p2.1-N218. The recombinant siRNA-expressing plasmids were transfected into Marc-145 cells; then the cells were infected with PRRSV (JL07SW strain); finally, after incubation for 48 h, the antiviral activity of those siRNA-expressing plasmids in Marc-145 cells was assessed by cytopathic effects, virus titers, indirect immunofluorescence, and quantitative real-time PCR. Experimental results demonstrated that these three siRNA-expressing plasmids could effectively and significantly inhibit the replication of PRRSV by 93.2%, 83.6%, and 89.2% in Marc-145 cells, respectively. Among these three siRNA-expressing plasmids, p2.1-N71 was found to be most effective, while p2.1-N144 and p2.1-N218 displayed relatively weak inhibition of virus replication. The results indicated that siRNA-expressing plasmids targeting the N gene of PRRSV could significantly inhibit PRRSV replication in Marc-145 cells. Based on our experimental results and previous reports, the 71–91, 179–197, and 234–252 sites of the N gene are good choices to effectively inhibit the replication of PRRSV, and this RNA interference technique can be a potential anti-PRRSV strategy.
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Affiliation(s)
- Minnan Yang
- College of Veterinary Medicine, and Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, 130062, P. R. China
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Zhao C, Liu S, Li C, Yang L, Zu Y. In vitro evaluation of the antiviral activity of the synthetic epigallocatechin gallate analog-epigallocatechin gallate (EGCG) palmitate against porcine reproductive and respiratory syndrome virus. Viruses 2014; 6:938-50. [PMID: 24566281 PMCID: PMC3939490 DOI: 10.3390/v6020938] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/13/2014] [Accepted: 02/12/2014] [Indexed: 11/16/2022] Open
Abstract
In this study, epigallocatechin gallate (EGCG) palmitate was synthesized and its anti-porcine reproductive and respiratory syndrome virus (PRRSV) activity was studied. Specifically, EGCG palmitate was evaluated for its ability to inhibit PRRSV infection in MARC-145 cells when administered as pre-, post-, or co-treatment. EGCG and ribavirin were used as controls. The results showed that a 50% cytotoxic concentration (CC50) of EGCG, EGCG palmitate, and ribavirin was achieved at 2,359.71, 431.42, and 94.06 μM, respectively. All three drugs inhibited PRRSV in a dose-dependent manner regardless of the treatment protocol. EGCG palmitate exhibited higher cytotoxicity than EGCG, but lower cytotoxicity than ribavirin. EGCG palmitate anti-PRRSV activity was significantly higher than that of EGCG and ribavirin, both as pre-treatment and post-treatment. Under the former conditions and a tissue culture infectious dose of 10 and 100, the selectivity index (SI) of EGCG palmitate in the inhibition of PRRSV was 3.8 and 2.9 times higher than that of ribavirin when administered as a pre-treatment, while the SI of EGCG palmitate in the inhibition of PRRSV was 3.0 and 1.9 times higher than ribavirin when administered as a post-treatment. Therefore, EGCG palmitate is potentially effective as an anti-PRRSV agent and thus of interest to the pharmaceutical industry.
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Affiliation(s)
- Chunjian Zhao
- State Engineering Laboratory for Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040, China.
| | - Shuaihua Liu
- State Engineering Laboratory for Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040, China.
| | - Chunying Li
- State Engineering Laboratory for Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040, China.
| | - Lei Yang
- State Engineering Laboratory for Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040, China.
| | - Yuangang Zu
- State Engineering Laboratory for Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040, China.
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Evaluation of Different DNA Vaccines against Porcine Reproductive and Respiratory Syndrome (PRRS) in Pigs. Vaccines (Basel) 2013; 1:463-80. [PMID: 26344342 PMCID: PMC4494207 DOI: 10.3390/vaccines1040463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/10/2013] [Accepted: 10/09/2013] [Indexed: 01/16/2023] Open
Abstract
In veterinary medicine, there have been different experiences with the plasmid DNA vaccination. In this area and with the hypothesis to demonstrate the effectiveness of different plasmids encoding porcine respiratory and reproductive syndrome (PRRS), five DNA vaccines against PRRS were evaluated for their innocuity and efficacy in pigs. Eighteen animals were divided into five groups which were injected with five (A, B, C, D, E) different DNA vaccines. Albeit, none of the proposed vaccines were able to protect the animals against PRRS virus. Only vaccines A and B were able to reduce the clinical signs of the infection. ELISA IgM were detected 30 days after the first vaccination in the pigs injected by Vaccine A or B. ELISA IgG were detected 90 days after the first vaccination in the pigs injected by Vaccine B or C. Neutralizing antibody were detected Post Challenge Days 61 (PCD) in all groups. In the pigs inoculated with Vaccine C, IFN-g were detected 90 days after first vaccination, and after challenge exposure they increased. In the other groups, the IFN-g were detected after challenge infection. Pigs injected with each of the vaccines A, B, C, D and E showed a significantly higher level of CD4(-)CD8⁺ lymphocytes (p < 0.001) after infection in comparison with their controls.
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Positive inductive effect of IL-18 on virus-specific immune responses induced by PRRSV-GP5 DNA vaccine in swine. Res Vet Sci 2013; 94:346-53. [DOI: 10.1016/j.rvsc.2012.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 07/27/2012] [Accepted: 09/06/2012] [Indexed: 11/18/2022]
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Pujhari S, Baig TT, Hansra S, Zakhartchouk AN. Development of a DNA-launched replicon as a vaccine for porcine reproductive and respiratory syndrome virus. Virus Res 2013; 173:321-6. [PMID: 23353778 DOI: 10.1016/j.virusres.2013.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/20/2012] [Accepted: 01/14/2013] [Indexed: 02/04/2023]
Abstract
Though a modified live attenuated vaccine (MLV) is available against porcine reproductive and respiratory syndrome virus (PRRSV), its limitations in protective efficacy, safety and few others warrant the development of newer vaccines. In this study, we have constructed a propagation-defective DNA-launched PRRSV replicon as a vaccine candidate and evaluated its immunogenicity and protective efficacy in a group of pigs along with MLV vaccinated group. Our data showed that prior to the intranasal challenge with a homologous strain of PRRSV, only MLV vaccinated pigs developed antibody response measured by ELISA and none of the pigs in any group developed PRRSV neutralizing antibodies in serum. The MLV vaccinated group also showed high PRRSV-specific INF-γ response, whereas the replicon-vaccinated pigs showed low but detectable INF-γ response. After 14 days post challenge, all groups showed similar PRRSV-specific serum neutralizing titers and were positive for PRRSV-specific ELISA antibody. In addition, the replicon-vaccinated group showed a significant reduction in viremia in comparison to the control group. In conclusion, vaccination with the PRRSV DNA-launched replicon decreased the viremia and viral load in bronchoalveolar lavage fluids of the PRRSV-challenged pigs and increased numbers of IFN-γ producing cells. Thus, the vaccine is partially protective and is a potential vaccine candidate for future with further improvement. The possible means of improvement is the expression of immunostimulatory genes by the replicon. We demonstrated the feasibility of this approach by expression of a foreign gene encoding firefly luciferase after transfection of cultured cells with the replicon plasmid DNA.
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Affiliation(s)
- Sujit Pujhari
- Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
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