Inhibitory Activity and Molecular Mechanism of Protegrin-1 against Porcine Reproductive and Respiratory Syndrome virus <i>in vitro</i>

Zhu

et al. 2017

J Virol

Self Cite

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause substantial economic losses to the pig industry worldwide. Heparan sulfate (HS) is used by PRRSV for initial attachment to target cells. However, the role of HS in the late phase of PRRSV infection and the mechanism of virus release from host cells remain largely unknown. In this study, we showed that PRRSV infection caused a decrease in HS expression and upregulated heparanase, the only known enzyme capable of degrading HS. We subsequently demonstrated that the NF-B signaling pathway and cathepsin L protease were involved in regulation of PRRSV infectioninduced heparanase. In addition, we found that ablation of heparanase expression using small interfering RNA duplexes increased cell surface expression of HS and suppressed PRRSV replication and release, whereas overexpression of heparanase reduced HS surface expression and enhanced PRRSV replication and release. These data suggest that PRRSV activates NF-B and cathepsin L to upregulate and process heparanase, and then the active heparanase cleaves HS, resulting in viral release. Our findings provide new insight into the molecular mechanism of PRRSV egress from host cells, which might help us to further understand PRRSV pathogenesis.IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) causes great economic losses each year to the pig industry worldwide. The molecular mechanism of PRRSV release from host cells largely remains a mystery. In this study, we demonstrate that PRRSV activates NF-B and cathepsin L to upregulate and process heparanase, and then the active heparanase is released to the extracellular space and exerts enzymatic activity to cleave heparan sulfate, resulting in viral release. Our findings provide new insight into the molecular mechanism of PRRSV egress from host cells, which might help us to further understand PRRSV pathogenesis.KEYWORDS PRRSV, heparan sulfate, heparanase, viral release, porcine reproductive and respiratory syndrome virus P orcine reproductive and respiratory syndrome (PRRS) has become one of the most important diseases of intensive pig production worldwide since its emergence in the late 1980s (1, 2). This disease is characterized by respiratory disease, weight loss, and poor growth performance, as well as by late-term abortions (3). The causative agent, PRRS virus (PRRSV), is a small, enveloped, positive-sense, single-stranded RNA virus of the genus Arterivirus, in the family Arteriviridae within the order Nidovirales (4, 5). The PRRSV genome is approximately 15 kb in length and consists of at least 12 overlapping open reading frames (6, 7). Due to the genetic and antigenic differences, PRRSV can be divided into European genotype 1 and North American genotype 2, with Lelystad and VR-2332 as prototypical strains, respectively, which share about 60% nucleotide sequence identity (8). In 2006, highly pathogenic PRRSV (HP-PRRSV)

Section: Cells and Virusesmentioning

confidence: 99%

Heparanase Upregulation Contributes to Porcine Reproductive and Respiratory Syndrome Virus Release

Zhu

et al. 2017

J Virol

Self Cite

Am J Respir Cell Mol Biol

“…Proteomic analysis indicates that many of the antimicrobial factors found in human airways can also be detected in porcine ASL, such as lactoferrin, lysozyme, SP-A, SP-D, SLPI, and numerous mucins including MUC1, -2, -4, -5B, -5AC, -13, - 16, and -19 (51). While LL-37 is unique to humans, porcine ASL contains a related molecule, the cathelicidin protegrin-1 (51), which displays antiviral activity against several different viruses (52,53). We expect that these proteins, and likely others, contribute to the broad-spectrum antiviral activity of porcine ASL.…”

Section: Discussionmentioning

confidence: 99%

Airway Surface Liquid Has Innate Antiviral Activity That Is Reduced in Cystic Fibrosis

Berkebile¹,

Bartlett²,

Alaiwa³

et al. 2020

While chronic bacterial infections and inflammation are associated with progressive lung disease in cystic fibrosis (CF) patients, much less is known regarding the contributions of respiratory viral infections to this process. Clinical studies suggest that antiviral host defenses may be compromised in individuals with CF, and CF airway epithelia exhibit impaired antiviral responses in vitro. Here, we used the CF pig model to test the hypothesis that the antiviral activity of respiratory secretions is reduced in CF. We developed an in vitro assay to measure the innate antiviral activity present in airway surface liquid (ASL) from CF and non-CF pigs. We found that tracheal and nasal ASL from newborn non-CF pigs exhibited dose-dependent inhibitory activity against several enveloped and encapsidated viruses including Sendai virus (SeV), respiratory syncytial virus (RSV), influenza A, and adenovirus. Importantly, we found that the anti-SeV activity of nasal ASL from newborn CF pigs was significantly diminished relative to non-CF littermate controls. This diminution of extracellular antiviral defenses appears to be driven, at least in part, by the differences in pH between CF and non-CF ASL. These data highlight the novel antiviral properties of native airway secretions, and suggest the possibility that defects in extracellular antiviral defenses contribute to CF pathogenesis.

“…Moreover, they demonstrated that the action of cathelicidins, either from animal or human, is by directly affecting the virus rather than by an induction of apoptosis or necrotic cell death (53). Regarding the anti-PRRSV activity of some HDPs, only a few studies are available (35, 36). In these studies anti-PRRSV properties were demonstrated for pBD-3 (35), a porcine HDP of the β-defensin family, and PG-1 (36), a protegrin originally isolated from porcine leukocytes.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, there is a strong interest in developing new vaccine candidates formulated with optimized adjuvant combinations. Regarding HDPs in the context of PRRSV infection, the literature is quite limited and, to our knowledge, antiviral activity against PRRSV has only been shown for a few HDPs such as protegrin 1 (PG-1), PG-4 and porcine β-defensin 3 (pBD-3) (35, 36).…”

Section: Introductionmentioning

confidence: 99%

Synthetic Cationic Peptide IDR-1002 and Human Cathelicidin LL37 Modulate the Cell Innate Response but Differentially Impact PRRSV Replication in vitro

et al. 2019

Host defense peptides (HDPs) show both antimicrobial and immunomodulatory properties making them important mediators of the host immune system. In humans but also in pigs many HDPs have been identified and important families such as cathelicidins and defensins have been established. In our study, we assessed: (i) the potential interactions that could occur between three peptides (LL37, PR39, and synthetic innate defense regulator (IDR)-1002) and a common TLR ligand called poly(I:C); (ii) the impact of selected peptides on the response of alveolar macrophage (AM) to poly(I:C) stimulation; (iii) the anti-porcine respiratory and reproductive syndrome virus (PRRSV) properties of the peptides; and (iv) their adjuvant potential in a PRRSV challenge experiment after immunization with different vaccine formulations. The results are as following: LL37, PR39, and IDR-1002 were able to interact with poly(I:C) using an agarose gel migration assay. Then, an alteration of AM's response to poly(I:C) stimulation was observed when the cells were co-stimulated with LL37 and IDR-1002. Regarding the anti-PRRSV potential of the peptides only LL37 showed a PRRSV inhibition in infected AM as well as precision cut lung slices (PCLS). However, in our conditions and despite their immunomodulatory properties, neither LL37 nor IDR-1002 showed any convincing potential as an adjuvant when associated to killed PRRSV in a challenge experiment. In conclusion, both antiviral and immunomodulatory properties could be identified for LL37, only immunomodulatory properties for IDR-1002, and both peptides failed to improve the immune response consecutive to an immunization with a killed vaccine in a PPRSV challenge experiment. However, further studies are needed to fully decipher and explain differences between peptide properties.