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Su N, Lin Z, Liu X, Sun X, Jin X, Feng H, Zhan C, Hu X, Gu C, Zhang W, Cheng G. Pathological observation and transcriptomic analysis of thymus injury in PRRSV-infected piglets. Vet Res Commun 2023; 47:1949-1962. [PMID: 37266866 DOI: 10.1007/s11259-023-10133-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 04/26/2023] [Indexed: 06/03/2023]
Abstract
The thymus, the central immune organ in mammals, plays an important role in immune defense. Porcine reproductive and respiratory syndrome virus (PRRSV) infection in piglets can cause thymus injury and immunosuppression. However, the mechanisms of thymus injury remain unknown. This study was aimed at investigating the specific manifestations of thymus injury through the construction of a PRRSV-infected piglet model and histopathological observation. In this study, fourteen 40-day-old PRRSV-free piglets were randomly divided into two groups, eleven of which were intramuscularly injected with 3 mL of PRRSV WUH3 virus suspension (106 PFU /mL) in the infection group, and three of which were sham-inoculated with 3 mL of RPMI-1640 medium in the control group. Clinical necropsy and samples collection were performed on day 8 after artificial infection. With the Illumina platform, the transcriptomes of piglet thymus tissues from infected and control piglets were sequenced to explore the relationships of differentially expressed genes (DEGs) and signaling pathways with thymus injury. The immune organs of PRRSV-infected piglets were severely damaged. The histopathological findings in the thymus indicated that PRRSV infection was associated with a large decrease in lymphocytes, cell necrosis and cell apoptosis; an increase in blood vessels and macrophages; thymic corpuscle hyperplasia; and interstitial widening of the thymic lobules. The transcriptomic analysis results revealed that the Gene Ontology functions of DEGs were enriched primarily in biological processes such as angiogenesis, regulation of angiogenesis and positive regulation of cell migration. Moreover, greater numbers of blood vessels and macrophages were observed in the thymus in PRRSV-infected than control piglets. KEGG pathway enrichment analysis revealed that the DEGs were significantly enriched in the Toll-like receptor signaling pathway, chemokine signaling pathway, IL-17 signaling pathway and TNF signaling pathway. The expression of TLR8, IRF5, the chemokines CCL2, CCL3L1 and CCL5; and their receptors CCR1, CCR2 and CCR5 was significantly up-regulated in PRRSV infection, thus suggesting that these cytokines were associated with the pathological processes of thymus injury.
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Affiliation(s)
- Naying Su
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
- Shanghai InnoStar Bio-tech Co., Ltd., Shanghai, China
| | - Zhengdan Lin
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Xi Liu
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Xiuxiu Sun
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Xinxin Jin
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Helong Feng
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
- Hubei Academy of Agricultural Sciences, Wuhan, Hubei Province, China
| | - Cunlin Zhan
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Xueying Hu
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Changqin Gu
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Wanpo Zhang
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Guofu Cheng
- College of Animal Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, China.
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Sinkora M, Toman M, Stepanova K, Stepanova H, Leva L, Sinkorova J, Moutelikova R, Salat J, Srutkova D, Schwarzer M, Sinkora S, Skalnikova HK, Nechvatalova K, Hudcovic T, Hermanova P, Pfeiferova S, Kratochvilova M, Kavanova L, Dusankova B, Sinkora MJ. The mechanism of immune dysregulation caused by porcine reproductive and respiratory syndrome virus (PRRSV). Microbes Infect 2023; 25:105146. [PMID: 37142116 DOI: 10.1016/j.micinf.2023.105146] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/27/2023] [Accepted: 04/27/2023] [Indexed: 05/06/2023]
Abstract
PRRSV is capable of evading the effective immune response, thus persisting in piglets and throughout the swine herd. We show here that PRRSV invades the thymus and causes depletion of T-cell precursors and alteration of the TCR repertoire. Developing thymocytes are affected during negative selection when they transit from the triple-negative to triple-positive stages at the corticomedullary junction just before entering the medulla. The restriction of repertoire diversification occurs in both helper and cytotoxic αβ-T cells. As a result, critical viral epitopes are tolerated, and infection becomes chronic. However, not all viral epitopes are tolerated. Infected piglets develop antibodies capable of recognizing PRRSV, but these are not virus neutralizing. Further analysis showed that the lack of an effective immune response against the critical viral structures results in the absence of a germinal center response, overactivation of T and B cells in the periphery, robust production of useless antibodies of all isotypes, and the inability to eliminate the virus. Overall, the results show how a respiratory virus that primarily infects and destroys myelomonocytic cells has evolved strategies to disrupt the immune system. These mechanisms may be a prototype for how other viruses can similarly modulate the host immune system.
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Affiliation(s)
- Marek Sinkora
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic.
| | - Miroslav Toman
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Katerina Stepanova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Hana Stepanova
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Lenka Leva
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Jana Sinkorova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Romana Moutelikova
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Jiri Salat
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Dagmar Srutkova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Martin Schwarzer
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Simon Sinkora
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Helena Kupcova Skalnikova
- Laboratory of Applied Proteome Analyses and Research Center PIGMOD, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Libechov, Czech Republic
| | - Katerina Nechvatalova
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Tomas Hudcovic
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Petra Hermanova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Sarka Pfeiferova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Mirka Kratochvilova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Lenka Kavanova
- Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic
| | - Blanka Dusankova
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
| | - Marek Jr Sinkora
- Laboratory of Gnotobiology, Institute of Microbiology, Czech Academy of Sciences, Novy Hradek, Czech Republic
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Peng O, Xia Y, Wei Y, Zeng S, Zou C, Hu F, Xu Q, Huang Y, Geng R, Hu G, Cao Y, Zhang H. Integrative transcriptomic profiling of mRNA, miRNA, circRNA, and lncRNA in alveolar macrophages isolated from PRRSV-infected porcine. Front Immunol 2023; 14:1258778. [PMID: 37691924 PMCID: PMC10491896 DOI: 10.3389/fimmu.2023.1258778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 08/09/2023] [Indexed: 09/12/2023] Open
Abstract
Introduction The porcine reproductive and respiratory syndrome virus (PRRSV) continues to pose a significant threat to the global swine industry, attributed largely to its immunosuppressive properties and the chronic nature of its infection. The absence of effective vaccines and therapeutics amplifies the urgency to deepen our comprehension of PRRSV's intricate pathogenic mechanisms. Previous transcriptomic studies, although informative, are partially constrained by their predominant reliance on in vitro models or lack of long-term infections. Moreover, the role of circular RNAs (circRNAs) during PRRSV invasion is yet to be elucidated. Methods In this study, we employed an in vivo approach, exposing piglets to a PRRSV challenge over varied durations of 3, 7, or 21 days. Subsequently, porcine alveolar macrophages were isolated for a comprehensive transcriptomic investigation, examining the expression patterns of mRNAs, miRNAs, circRNAs, and long non-coding RNAs (lncRNAs). Results Differentially expressed RNAs from all four categories were identified, underscoring the dynamic interplay among these RNA species during PRRSV infection. Functional enrichment analyses indicate that these differentially expressed RNAs, as well as their target genes, play a pivotal role in immune related pathways. For the first time, we integrated circRNAs into the lncRNA-miRNA-mRNA relationship, constructing a competitive endogenous RNA (ceRNA) network. Our findings highlight the immune-related genes, CTLA4 and SAMHD1, as well as their associated miRNAs, lncRNAs, and circRNAs, suggesting potential therapeutic targets for PRRS. Importantly, we corroborated the expression patterns of selected RNAs through RT-qPCR, ensuring consistency with our transcriptomic sequencing data. Discussion This study sheds lights on the intricate RNA interplay during PRRSV infection and provides a solid foundation for future therapeutic strategizing.
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Affiliation(s)
- Ouyang Peng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yu Xia
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ying Wei
- College of Animal Science and Technology/Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang, China
| | - Siying Zeng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chuangchao Zou
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Fangyu Hu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qiuping Xu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yihui Huang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Rui Geng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Guangli Hu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yongchang Cao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Hao Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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Sun Q, Xu H, An T, Cai X, Tian Z, Zhang H. Recent Progress in Studies of Porcine Reproductive and Respiratory Syndrome Virus 1 in China. Viruses 2023; 15:1528. [PMID: 37515213 PMCID: PMC10384046 DOI: 10.3390/v15071528] [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: 06/19/2023] [Revised: 06/30/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Due to the high incidence of PRRSV mutation and recombination, PRRSV infection is difficult to prevent and control in China and worldwide. Two species of PRRSV, Betaarterivirus suid 1 (PRRSV-1) and Betaarterivirus suid 2 (PRRSV-2), exist in China, and PRRSV-1 has always received less attention in China. However, the number of PRRSV-1 strains detected in China has increased recently. To date, PRRSV-1 has spread to more than 23 regions in China. Based on the phylogenetic analysis of ORF5 and the whole genome of PRRSV-1, Chinese PRRSV-1 can be divided into at least seven independent subgroups. Among them, BJEU06-1-like has become the mainstream subgroup in some regions of China. This subgroup of strains has a 5-aa (4 + 1) characteristic discontinuous deletion pattern at aa 357~aa 360 and aa 411 in Nsp2. Previous studies have indicated that the pathogenicity of PRRSV-1 in China is mild, but recent studies found that the pathogenicity of PRRSV-1 was enhanced in China. Therefore, the emergence of PRRSV-1 deserves attention, and the prevention and control of PRRSV-1 infection in China should be strengthened. PRRSV infection is usually prevented and controlled by a combination of virus monitoring, biosafety restrictions, herd management measures and vaccination. However, the use of PRRSV-1 vaccines is currently banned in China. Thus, we should strengthen the monitoring of PRRSV-1 and the biosafety management of pig herds in China. In this review, we summarize the prevalence of PRRSV-1 in China and clarify the genomic characteristics, pathogenicity, vaccine status, and prevention and control management system of PRRSV-1 in China. Consequently, the purpose of this review is to provide a basis for further development of prevention and control measures for PRRSV-1.
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Affiliation(s)
- Qi Sun
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
| | - Hu Xu
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
| | - Tongqing An
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
| | - Xuehui Cai
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
| | - Zhijun Tian
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
| | - Hongliang Zhang
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 678 Haping Road, Xiangfang District, Harbin 150001, China
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Cai H, Zhang H, Cheng H, Liu M, Wen S, Ren J. Progress in PRRSV Infection and Adaptive Immune Response Mechanisms. Viruses 2023; 15:1442. [PMID: 37515130 PMCID: PMC10385784 DOI: 10.3390/v15071442] [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: 06/02/2023] [Revised: 06/21/2023] [Accepted: 06/25/2023] [Indexed: 07/30/2023] Open
Abstract
Since its discovery, Porcine reproductive and respiratory syndrome (PRRS) has had a huge impact on the farming industry. The virus that causes PRRS is Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), and because of its genetic diversity and the complexity of the immune response, the eradication of PRRS has been a challenge. To provide scientific references for PRRSV control and vaccine development, this study describes the processes of PRRSV-induced infection and escape, as well as the host adaptive immune response to PRRSV. It also discusses the relationship between PRRSV and the adaptive immune response.
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Affiliation(s)
- Huanchang Cai
- Wenzhou Key Laboratory for Virology and Immunology, Institute of Virology, Wenzhou University, Wenzhou 325035, China
| | - Hewei Zhang
- College of Food and Drugs, Luoyang Polytechnic, Luoyang 471099, China
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang 471000, China
| | - Huai Cheng
- Wenzhou Key Laboratory for Virology and Immunology, Institute of Virology, Wenzhou University, Wenzhou 325035, China
| | - Min Liu
- Wenzhou Key Laboratory for Virology and Immunology, Institute of Virology, Wenzhou University, Wenzhou 325035, China
| | - Shubo Wen
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Jingqiang Ren
- Wenzhou Key Laboratory for Virology and Immunology, Institute of Virology, Wenzhou University, Wenzhou 325035, China
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang 471000, China
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Cui Z, Zhou L, Hu X, Zhao S, Xu P, Li W, Chen J, Zhang Y, Xia P. Immune Molecules' mRNA Expression in Porcine Alveolar Macrophages Co-Infected with Porcine Reproductive and Respiratory Syndrome Virus and Porcine Circovirus Type 2. Viruses 2023; 15:v15030777. [PMID: 36992486 PMCID: PMC10058123 DOI: 10.3390/v15030777] [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: 02/16/2023] [Revised: 03/12/2023] [Accepted: 03/14/2023] [Indexed: 03/31/2023] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus 2 (PCV2) are economically important pathogens in swine, and pigs with dual infections of PCV2 and PRRSV consistently have more severe clinical symptoms and interstitial pneumonia. However, the synergistic pathogenesis mechanism induced by PRRSV and PCV2 co-infection has not yet been illuminated. Therefore, the aim of this study was to characterize the kinetic changes of immune regulatory molecules, inflammatory factors and immune checkpoint molecules in porcine alveolar macrophages (PAMs) in individuals infected or co-infected with PRRSV and/or PCV2. The experiment was divided into six groups: a negative control group (mock, no infected virus), a group infected with PCV2 alone (PCV2), a group infected with PRRSV alone (PRRSV), a PCV2-PRRSV co-infected group (PCV2-PRRSV inoculated with PCV2, followed by PRRSV 12 h later), a PRRSV-PCV2 co-infected group (PRRSV-PCV2 inoculated with PRRSV, followed by PCV2 12 h later) and a PCV2 + PRRSV co-infected group (PCV2 + PRRSV, inoculated with PCV2 and PRRSV at the same time). Then, PAM samples from the different infection groups and the mock group were collected at 6, 12, 24, 36 and 48 h post-infection (hpi) to detect the viral loads of PCV2 and PRRSV and the relative quantification of immune regulatory molecules, inflammatory factors and immune checkpoint molecules. The results indicated that PCV2 and PRRSV co-infection, regardless of the order of infection, had no effect on promoting PCV2 replication, while PRRSV and PCV2 co-infection was able to promote PRRSV replication. The immune regulatory molecules (IFN-α and IFN-γ) were significantly down-regulated, while inflammatory factors (TNF-α, IL-1β, IL-10 and TGF-β) and immune checkpoint molecules (PD-1, LAG-3, CTLA-4 and TIM-3) were significantly up-regulated in the PRRSV and PCV2 co-infection groups, especially in PAMs with PCV2 inoculation first followed by PRRSV. The dynamic changes in the aforementioned immune molecules were associated with a high viral load, immunosuppression and cell exhaustion, which may explain, at least partially, the underlying mechanism of the enhanced pulmonary lesions by dual infection with PCV2 and PRRSV in PAMs.
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Affiliation(s)
- Zhiying Cui
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Likun Zhou
- College of Life Science, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Xingxing Hu
- Zhongnong Huada (Wuhan) Testing Technology Co., Ltd., Luoshi South Road#519, Hongshan District, Wuhan 430070, China
| | - Shijie Zhao
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Pengli Xu
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Wen Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Jing Chen
- College of Life Science, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Yina Zhang
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
| | - Pingan Xia
- College of Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake 15#, Zhengzhou 450046, China
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Ruedas-Torres I, Sánchez-Carvajal JM, Carrasco L, Pallarés FJ, Larenas-Muñoz F, Rodríguez-Gómez IM, Gómez-Laguna J. PRRSV-1 induced lung lesion is associated with an imbalance between costimulatory and coinhibitory immune checkpoints. Front Microbiol 2023; 13:1007523. [PMID: 36713151 PMCID: PMC9878400 DOI: 10.3389/fmicb.2022.1007523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 12/16/2022] [Indexed: 01/15/2023] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) induces a dysregulation on the innate and adaptive immune responses. T-cell activation requires a proper interaction and precise balance between costimulatory and coinhibitory molecules, commonly known as immune checkpoints. This study aims to evaluate the expression of immune checkpoints in lung and tracheobronchial lymph node from piglets infected with two PRRSV-1 strains of different virulence during the early stage of infection. Seventy 4-week-old piglets were grouped into three experimental groups: (i) control, (ii) 3249-infected group (low virulent strain), and (iii) Lena-infected group (virulent strain) and were euthanized at 1, 3, 6, 8, and 13 days post-infection (dpi). Lung and tracheobronchial lymph node were collected to evaluate histopathological findings, PRRSV viral load and mRNA expression of costimulatory (CD28, CD226, TNFRSF9, SELL, ICOS, and CD40) and coinhibitory (CTLA4, TIGIT, PD1/PDL1, TIM3, LAG3, and IDO1) molecules through RT-qPCR. Our findings highlight a mild increase of costimulatory molecules together with an earlier and stronger up-regulation of coinhibitory molecules in both organs from PRRSV-1-infected animals, especially in the lung from virulent Lena-infected animals. The simultaneous expression of coinhibitory immune checkpoints could work in synergy to control and limit the inflammation-induced tissue damage. Further studies should be addressed to determine the role of these molecules in later stages of PRRSV infection.
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Time-series transcriptomic analysis of bronchoalveolar lavage cells from virulent and low virulent PRRSV-1-infected piglets. J Virol 2021; 96:e0114021. [PMID: 34851149 PMCID: PMC8826917 DOI: 10.1128/jvi.01140-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) has evolved to escape the immune surveillance for a survival advantage leading to a strong modulation of host’s immune responses and favoring secondary bacterial infections. However, limited data are available on how the immunological and transcriptional responses elicited by virulent and low-virulent PRRSV-1 strains are comparable and how they are conserved during the infection. To explore the kinetic transcriptional signature associated with the modulation of host immune response at lung level, a time-series transcriptomic analysis was performed in bronchoalveolar lavage cells upon experimental in vivo infection with two PRRSV-1 strains of different virulence, virulent subtype 3 Lena strain or the low-virulent subtype 1 3249 strain. The time-series analysis revealed overlapping patterns of dysregulated genes enriched in T-cell signaling pathways among both virulent and low-virulent strains, highlighting an upregulation of co-stimulatory and co-inhibitory immune checkpoints that were disclosed as Hub genes. On the other hand, virulent Lena infection induced an early and more marked “negative regulation of immune system process” with an overexpression of co-inhibitory receptors genes related to T-cell and NK cell functions, in association with more severe lung lesion, lung viral load, and BAL cell kinetics. These results underline a complex network of molecular mechanisms governing PRRSV-1 immunopathogenesis at lung level, revealing a pivotal role of co-inhibitory and co-stimulatory immune checkpoints in the pulmonary disease, which may have an impact on T-cell activation and related pathways. These immune checkpoints, together with the regulation of cytokine-signaling pathways, modulated in a virulence-dependent fashion, orchestrate an interplay among pro- and anti-inflammatory responses. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the major threats to swine health and global production, causing substantial economic losses. We explore the mechanisms involved in the modulation of host immune response at lung level performing a time-series transcriptomic analysis upon experimental infection with two PRRSV-1 strains of different virulence. A complex network of molecular mechanisms was revealed to control the immunopathogenesis of PRRSV-1 infection, highlighting an interplay among pro- and anti-inflammatory responses as a potential mechanism to restrict inflammation-induced lung injury. Moreover, a pivotal role of co-inhibitory and co-stimulatory immune checkpoints was evidenced, which may lead to progressive dysfunction of T cells, impairing viral clearance and leading to persistent infection, favoring as well secondary bacterial infections or viral rebound. However, further studies should be conducted to evaluate the functional role of immune checkpoints in advanced stages of PRRSV infection and explore a possible T-cell exhaustion state.
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Porcine reproductive and respiratory syndrome virus infection upregulates negative immune regulators and T-cell exhaustion markers. J Virol 2021; 95:e0105221. [PMID: 34379512 DOI: 10.1128/jvi.01052-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porcine alveolar macrophage (PAM) is one of the primary cellular targets for PRRSV, but less than 2% of PAMs are infected with the virus during the acute stage of infection. To comparatively analyze the host transcriptional response between PRRSV-infected PAMs and bystanders PAMs that remained uninfected but were exposed to the inflammatory milieu of an infected lung, pigs were infected with a PRRSV strain expressing green fluorescent protein (PRRSV-GFP) and GFP+ (PRRSV infected) and GFP- (bystander) cells were sorted for RNA-sequencing (RNA-seq). Approximately 4.2% of RNA reads from GFP+ and 0.06% reads from GFP- PAMs mapped to the PRRSV genome, indicating that PRRSV-infected PAMs were effectively separated from bystander PAMs. Further analysis revealed that inflammatory cytokines, interferon-stimulated genes, and antiviral genes were highly upregulated in GFP+ as compared to GFP- PAMs. Importantly, negative immune regulators including NF-κB inhibitors (NFKBIA, NFKBID, NFKBIZ, and TNFAIP3), and T-cell exhaustion markers (PD-L1, PD-L2, IL10, IDO1, and TGFB2) were highly upregulated in GFP+ cells as compared to GFP- cells. By using in situ hybridization assay, RNA transcripts of TNF and NF-κB inhibitors were detected in PRRSV-infected PAMs cultured ex vivo and lung sections of PRRSV-infected pigs during the acute stage of infection. Collectively, the results suggest that PRRSV infection upregulates expression of negative immune regulators and T-cell exhaustion markers in PAMs to modulate the host immune response. Our findings provide further insight into PRRSV immunopathogenesis. Importance PRRSV is widespread in many swine producing countries, causing substantial economic loses to the swine industry. PAM is considered the primary target for PRRSV replication in pigs. However, less than 2% of PAM from an acutely infected pigs are infected with the virus. In the present study, we utilized a PRRSV-GFP strain to infect pigs and sorted infected- and bystander- PAMs from the pigs during the acute stage of infection for transcriptome analysis. PRRSV infected PAMs showed a distinctive gene expression profile and contained many uniquely activated pathways compared to bystander PAMs. Interestingly, upregulated expression of and NF-κB signaling inhibitors and T-cell exhaustion molecules were observed in PRRSV-infected PAMs. Our findings provide additional knowledge on the mechanisms that PRRSV employs to modulate the host immune system.
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