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18 pages, 2481 KiB

Open AccessArticle

Immune Molecules’ mRNA Expression in Porcine Alveolar Macrophages Co-Infected with Porcine Reproductive and Respiratory Syndrome Virus and Porcine Circovirus Type 2

by Zhiying Cui, Likun Zhou, Xingxing Hu, Shijie Zhao, Pengli Xu, Wen Li, Jing Chen, Yina Zhang and Pingan Xia

Viruses 2023, 15(3), 777; https://doi.org/10.3390/v15030777 - 17 Mar 2023

Cited by 2 | Viewed by 1845

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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18 pages, 3296 KiB

Open AccessArticle

Toll-like Receptor-Mediated Immunomodulation of Th1-Type Response Stimulated by Recombinant Antigen of Type 2 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV-2)

by Rika Wahyuningtyas, Mei-Li Wu, Wen-Bin Chung, Hso-Chi Chaung and Ko-Tung Chang

Viruses 2023, 15(3), 775; https://doi.org/10.3390/v15030775 - 17 Mar 2023

Cited by 2 | Viewed by 1852

Abstract

PRRSV infects CD163-positive macrophages and skews their polarization toward an M2 phenotype, followed by T-cell inactivation. In our previous study, we found that recombinant protein A1 antigen derived from PRRSV-2 was a potential vaccine or adjuvant for immunization against PRRSV-2 infection due to [...] Read more.

PRRSV infects CD163-positive macrophages and skews their polarization toward an M2 phenotype, followed by T-cell inactivation. In our previous study, we found that recombinant protein A1 antigen derived from PRRSV-2 was a potential vaccine or adjuvant for immunization against PRRSV-2 infection due to its ability to repolarize macrophages into M1 subtype, thereby reducing CD163 expression for viral entry and promoting immunomodulation for Th1-type responses, except for stimulating Toll-like receptor (TLR) activation. The aim of our current study was to evaluate the effects of another two recombinant antigens, A3 (ORF6L5) and A4 (NLNsp10L11), for their ability to trigger innate immune responses including TLR activation. We isolated pulmonary alveolar macrophages (PAMs) from 8- to 12-week-old specific pathogen free (SPF) piglets and stimulated them with PRRSV (0.01 MOI and 0.05 MOI) or antigens. We also investigated the T-cell differentiation by immunological synapse activation of PAMs and CD4⁺ T-cells in the cocultured system. To confirm the infection of PRRSV in PAMs, we checked the expression of TLR3, 7, 8, and 9. Our results showed that the expression of TLR3, 7, and 9 were significantly upregulated in PAMs by A3 antigen induction, similar to the extent of PRRSV infection. Gene profile results showed that A3 repolarizes macrophages into the M1 subtype potently, in parallel with A1, as indicated by significant upregulation of proinflammatory genes (TNF-α, IL-6, IL-1β and IL-12). Upon immunological synapse activation, A3 potentially differentiated CD4 T cells into Th1 cells, determined by the expression of IL-12 and IFN-γ secretion. On the contrary, antigen A4 promoted regulatory T cell (T-reg) differentiation by significant upregulation of IL-10 expression. Finally, we concluded that the PRRSV-2 recombinant protein A3 provided better protection against PRRSV infection, suggested by its capability to reeducate immunosuppressive M2 macrophages into proinflammatory M1 cells. As M1 macrophages are prone to be functional antigen-presenting cells (APCs), they can call for TLR activation and Th1-type immune response within the immunological synapse. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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12 pages, 2527 KiB

Open AccessArticle

Manganese Mediates Its Antiviral Functions in a cGAS-STING Pathway Independent Manner

by Shaohua Sun, Yulin Xu, Ming Qiu, Sen Jiang, Qi Cao, Jia Luo, Tangjie Zhang, Nanhua Chen, Wanglong Zheng, Francois Meurens, Zongping Liu and Jianzhong Zhu

Viruses 2023, 15(3), 646; https://doi.org/10.3390/v15030646 - 28 Feb 2023

Cited by 4 | Viewed by 1846

Abstract

The innate immune system is the first line of host defense sensing viral infection. Manganese (Mn) has recently been found to be involved in the activation of the innate immune DNA-sensing cGAS-STING pathway and subsequent anti-DNA virus function. However, it is still unclear [...] Read more.

The innate immune system is the first line of host defense sensing viral infection. Manganese (Mn) has recently been found to be involved in the activation of the innate immune DNA-sensing cGAS-STING pathway and subsequent anti-DNA virus function. However, it is still unclear whether Mn²⁺ mediates host defense against RNA viruses. In this study, we demonstrate that Mn²⁺ exhibited antiviral effects against various animal and human viruses, including RNA viruses such as PRRSVs and VSV, as well as DNA viruses such as HSV1, in a dose-dependent manner. Moreover, cGAS and STING were both investigated in the Mn²⁺ mediated antiviral roles using the knockout cells made by the CRISPR-Cas9 approach. Unexpectedly, the results revealed that neither cGAS knockout nor STING knockout had any effect on Mn²⁺-mediated antiviral functions. Nevertheless, we verified that Mn²⁺ promoted the activation of the cGAS-STING signaling pathway. These findings suggest that Mn²⁺ has broad-spectrum antiviral activities in a cGAS-STING pathway independent manner. This study also provides significant insights into redundant mechanisms participating in the Mn²⁺ antiviral functions, and also indicates a new target for Mn²⁺ antiviral therapeutics. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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16 pages, 1174 KiB

Open AccessArticle

Follow-Up of PRRSv-Vaccinated Piglets Born from PRRSv-Vaccinated, ELISA-Seropositive and ELISA-Seronegative Sows

by Jorian Fiers, Marylène Tignon, Dominiek Maes and Ann-Brigitte Cay

Viruses 2023, 15(2), 479; https://doi.org/10.3390/v15020479 - 9 Feb 2023

Cited by 4 | Viewed by 1630

Abstract

Vaccination against the porcine reproductive and respiratory syndrome virus (PRRSv) is widely used to prevent production losses in the swine industry. In this study, piglets born from both PRRSv-vaccinated ELISA-seropositive sows (E+ piglets) and PRRSv-vaccinated ELISA-seronegative sows (E− piglets) were followed-up pre-vaccination, 3 [...] Read more.

Vaccination against the porcine reproductive and respiratory syndrome virus (PRRSv) is widely used to prevent production losses in the swine industry. In this study, piglets born from both PRRSv-vaccinated ELISA-seropositive sows (E+ piglets) and PRRSv-vaccinated ELISA-seronegative sows (E− piglets) were followed-up pre-vaccination, 3 weeks post-vaccination (wpv) and 8 wpv in two Belgian farrow-to-finish herds. The aim of the study was to analyze the presence of PRRSv-specific maternally-derived antibodies (MDAs) and the PRRSv vaccine response in both groups of piglets. The E− piglets lacked the presence of PRRSv-specific MDAs (0% seropositive), while these were present in the E+ piglets (97% seropositive). Due to this, the E− piglets showed a strong initial vaccine response (72–80% seroconversion) and vaccine viremia (65–75% PCR positive) at 3 wpv. In contrast, the E+ piglets showed only limited initial vaccine responses (25–61% with increased ELISA values) and vaccine viremia (30–31% PCR positive) at 3 wpv. By 8 wpv, the proportion of seropositive E− piglets (78–100%) and seropositive E+ piglets (55–90%) increased in both herds. However, a difference in vaccine viremia duration was observed between both herds at 8 wpv, with a decrease in the proportion of PCR positive piglets in herd 1 (E−: 47%; E+: 25%) and an increase in the proportion of PCR positive piglets in herd 2 (E−: 85%; E+: 92%). This study identified clear differences in the presence of PRRSv-specific maternally-derived antibodies and PRRSv vaccine responses between E− and E+ piglets. Further research is warranted to elicit the biological relevance of these observed differences. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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15 pages, 2998 KiB

Open AccessArticle

Proteomic Characterization of PAMs with PRRSV-ADE Infection

by Pengli Xu, Wen Li, Shijie Zhao, Zhiying Cui, Yu Chen, Yi-na Zhang, Jing Chen and Pingan Xia

Viruses 2023, 15(1), 36; https://doi.org/10.3390/v15010036 - 22 Dec 2022

Cited by 5 | Viewed by 1698

Abstract

The antibody-dependent enhancement (ADE) effect of a PRRSV infection is that the preexisting sub- or non-neutralizing antibodies specific against PRRSV can facilitate the virus entry and replication, and it is likely to be a great obstacle for the selection of immune strategies and [...] Read more.

The antibody-dependent enhancement (ADE) effect of a PRRSV infection is that the preexisting sub- or non-neutralizing antibodies specific against PRRSV can facilitate the virus entry and replication, and it is likely to be a great obstacle for the selection of immune strategies and the development of high-efficiency PRRSV vaccines. However, the proteomic characterization of primary alveolar macrophages (PAMs) with a PRRSV-ADE infection has not yet been investigated so far. Therefore, we performed a tandem mass tag (TMT)-based quantitative proteomic analysis of PAMs with a PRRSV-ADE infection in this study. The results showed that a total of 3935 differentially expressed proteins (DEPs) were identified in the PAMs infected with PRRSV-ADE, including 2004 up-regulated proteins and 1931 down-regulated proteins. Further, the bioinformatics analysis for these DEPs revealed that a PRRSV-ADE infection might disturb the functions of ribosome, proteasome and mitochondria. Interestingly, we also found that the expression of the key molecules in the innate immune pathways and antiviral proteins were significantly down-regulated during a PRRSV-ADE infection. This study was the first attempt to analyze the proteomic characterization of PAMs with a PRRSV-ADE infection in vitro. Additionally, the findings will provide valuable information for a better understanding of the mechanism of virus–antibody–host interactions during a PRRSV-ADE infection. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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16 pages, 1484 KiB

Open AccessArticle

Effect of BIO-PLY^TM, a Platelet-Rich Plasma Derived Biologic on PRRSV-2-Infected Macrophages

by Alba Frias-De-Diego, Jessica M. Gilbertie, Frank Scholle, Sarah Dejarnette and Elisa Crisci

Viruses 2022, 14(12), 2666; https://doi.org/10.3390/v14122666 - 28 Nov 2022

Viewed by 1657

Abstract

Porcine Reproductive and Respiratory Syndrome (PRRS) is the one of the most devastating diseases impacting the swine industry worldwide. Control and prevention methods rely on biosafety measures and vaccination. As an RNA virus with a high rate of mutation, vaccines are only partially [...] Read more.

Porcine Reproductive and Respiratory Syndrome (PRRS) is the one of the most devastating diseases impacting the swine industry worldwide. Control and prevention methods rely on biosafety measures and vaccination. As an RNA virus with a high rate of mutation, vaccines are only partially effective against circulating and newly emerging strains. To reduce the burden of this disease, research on alternative control methods is needed. Here, we assess the in vitro antiviral effect of a novel platelet-rich plasma-derived biologic termed BIO-PLY^TM (for the BIOactive fraction of Platelet-rich plasma LYsate) from both swine and equine origin. Our results show that BIO-PLY^TM significantly reduces the amount of PRRSV viral load determined by RT-qPCR and the number of infectious viral particles measured by TCID50 in infected porcine alveolar and parenchymal macrophages. This study also showed limited toxicity of BIO-PLY^TM in vitro and aspects of its immunomodulatory capacity evaluating the regulation of reactive oxygen species and cytokines production in infected cells. Finally, this study presents promising data on the effect of BIO-PLY^TM on other RNA viruses such as human A influenza viruses and coronavirus. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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20 pages, 1461 KiB

Open AccessArticle

Porcine Reproductive and Respiratory Syndrome virus (PRRSv): A Cross-Sectional Study on ELISA Seronegative, Multivaccinated Sows

by Jorian Fiers, Marylène Tignon, Ann Brigitte Cay, Xavier Simons and Dominiek Maes

Viruses 2022, 14(9), 1944; https://doi.org/10.3390/v14091944 - 31 Aug 2022

Cited by 7 | Viewed by 2619

Abstract

Vaccination against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) is widely used to control clinical disease, but the effectiveness appears in some cases to be suboptimal. Field reports have stated the presence of routinely PRRSv-vaccinated but ELISA seronegative sows: the ELISA non-responders. The [...] Read more.

Vaccination against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) is widely used to control clinical disease, but the effectiveness appears in some cases to be suboptimal. Field reports have stated the presence of routinely PRRSv-vaccinated but ELISA seronegative sows: the ELISA non-responders. The real extent of this phenomenon (prevalence–origin–consequences) was not yet investigated. In this study, the prevalence of ELISA non-responders was assessed by measuring PRRSv-specific antibodies in 1400 sows, originating from 70 PRRSv-vaccinating sow herds, using IDEXX ELISA (ELISA 1) and CIVTEST E/S ELISA (ELISA 2). Neutralizing antibodies (NAbs) were quantified in a virus neutralization assay. Univariable logistic regression was used to identify herd risk factors for the presence of ELISA non-responders. The global prevalence of non-responders varied from 3.5% (ELISA 1) to 4.1% (ELISA 2), the herd-level prevalence was 40% and the within-herd prevalence ranged from 5% to 20% (ELISA 1) and from 5% to 30% (ELISA 2). The ELISA non-responders had significantly lower NAbs than the ELISA responders. Herds using the combination of one modified live vaccine and one killed vaccine had a significantly reduced risk of having ELISA non-responders. A first assessment of the prevalence and possible consequences of ELISA non-responders has been provided by this study. The clinical importance, origin and underlying immunological mechanisms warrant further research. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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14 pages, 3047 KiB

Open AccessArticle

Differences in Humoral Immune Response against the Type 2 Porcine Reproductive and Respiratory Syndrome Virus via Different Immune Pathways

by Wen Li, Yangyang Sun, Shijie Zhao, Zhiying Cui, Yu Chen, Pengli Xu, Jing Chen, Yina Zhang and Pingan Xia

Viruses 2022, 14(7), 1435; https://doi.org/10.3390/v14071435 - 29 Jun 2022

Cited by 5 | Viewed by 1569

Abstract

The intramuscular vaccine is the principal strategy to protect pigs from porcine reproductive and respiratory syndrome virus (PRRSV), However, it is still difficult to control PRRSV effectively. This study infected piglets with PRRSV through intramuscular and intranasal inoculation. Subsequently, viral loads, anti-PRRSV antibody [...] Read more.

The intramuscular vaccine is the principal strategy to protect pigs from porcine reproductive and respiratory syndrome virus (PRRSV), However, it is still difficult to control PRRSV effectively. This study infected piglets with PRRSV through intramuscular and intranasal inoculation. Subsequently, viral loads, anti-PRRSV antibody levels, and neutralizing antibodies (NAs) titers in both serum and saliva were monitored for 43 days. Meanwhile, tissues were obtained through necropsy at 43 days post-inoculation (dpi) to detect viral loads. The results indicated that viremia lasted from 3 to 31 dpi in both the inoculation groups, but the viruses survived in the lungs and lymph nodes after viremia clearance. The antibody response was detected from 11 dpi, but the response of NAs was delayed until 3–4 weeks. Furthermore, intranasal inoculation induced lower viral load levels than injection inoculation. In addition, positive SIgA and NAs levels were produced early, with higher levels through intranasal inoculation. Therefore, our data indicated that a more robust antibody response and lower virus loads could be induced by intranasal inoculation, and mucosal inoculation could be a suitable pathway for PRRSV vaccines. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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15 pages, 2607 KiB

Open AccessArticle

Paraoxonase-1 Facilitates PRRSV Replication by Interacting with Viral Nonstructural Protein-9 and Inhibiting Type I Interferon Pathway

by Lin Zhang, Yu Pan, Yunfei Xu, Wenli Zhang, Wenjie Ma, Yassein M. Ibrahim, Gebremeskel Mamu Werid, He Zhang, Changyou Xia, Ping Wei, Hongyan Chen and Yue Wang

Viruses 2022, 14(6), 1203; https://doi.org/10.3390/v14061203 - 31 May 2022

Cited by 5 | Viewed by 1941

Abstract

Paraoxonase-1 (PON1), an esterase with specifically paraoxonase activity, has been proven to be involved in inflammation and infection. Porcine reproductive and respiratory syndrome virus (PRRSV) is still a major concern in pigs and causes severe economic losses to the swine industry worldwide. In [...] Read more.

Paraoxonase-1 (PON1), an esterase with specifically paraoxonase activity, has been proven to be involved in inflammation and infection. Porcine reproductive and respiratory syndrome virus (PRRSV) is still a major concern in pigs and causes severe economic losses to the swine industry worldwide. In this study, the role of PON1 was investigated in porcine alveolar macrophages (PAMs) during PRRSV infection. The results showed that PRRSV replication downregulated PON1, and the knockdown of PON1 significantly decreased PRRSV replication. Similarly, PON1 overexpression could enhance PRRSV replication. Interestingly, we observed that PON1 interacted with PRRSV nonstructural protein 9 (Nsp9), the RNA-dependent RNA polymerase, and the knockdown of PON1 lowered the RNA binding ability of Nsp9, suggesting that PON1 can facilitate Nsp9 function in viral replication. In addition, the knockdown of PON1 expression led to the amplification of type I interferon (IFN) genes and vice versa. In summary, our data demonstrate that PON1 facilitates PRRSV replication by interacting with Nsp9 and inhibiting the type I IFN signaling pathway. Hence, PON1 may be an additional component of the anti-PRRSV defenses. Full article

(This article belongs to the Special Issue PRRSV: Vaccinology and Immunology)

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