Molecular cloning of porcine 2′,5′-oligoadenylate synthetase-like protein and its role in porcine reproductive and respiratory syndrome virus infection

The shape-dependent inhibitory effect of rhein/silver nanocomposites on porcine reproductive and respiratory syndrome virus

Traditional Chinese medicines (TCMs)/nanopreparations as viral antagonists exhibited a structure-function correlation, i.e., the differences in surface area/volume ratio caused by the variations in shape and size could result in different biochemical properties and biological activities, suggesting an important impact of morphology and structure on the antiviral activity of TCM-based nanoparticles. However, few studies paid attention to this aspect. Here, the effect of TCM-based nanoparticles with different morphologies on their antiviral activity was explored by synthesizing rhein/silver nanocomposites (Rhe@AgNPs) with spherical (S-Rhe/Ag) and linear (L-Rhe/Ag) morphologies, using rhein (an active TCM ingredient) as a reducing agent and taking its self-assembly advantage. Using porcine reproductive and respiratory syndrome virus (PRRSV) as a model virus, the inhibitory effects of S-Rhe/Ag and L-Rhe/Ag on PRRSV were compared. Results showed that the product morphology could be regulated by varying pH values, and both S- and L-Rhe/Ag exhibited good dispersion and stability, but with a smaller size for L-Rhe/Ag. Antiviral experiments revealed that Rhe@AgNPs could effectively inhibit PRRSV infection, but the antiviral effect was morphology-dependent. Compared with L-Rhe/Ag, S-Rhe/Ag could more effectively inactivate PRRSV in vitro and antagonize its adsorption, invasion, replication, and release stages. Mechanistic studies indicated that Rhe@AgNPs could reduce the production of reactive oxygen species (ROS) induced by PRRSV infection, and S-Rhe/Ag also had stronger ROS inhibitory effect. This work confirmed the inhibitory effect of Rhe@AgNPs with different morphologies on PRRSV and provided useful information for treating PRRSV infection with metal nanoparticles synthesized from TCM ingredients.

TRIM4-mediated ubiquitination of NSP2 restricts porcine reproductive and respiratory syndrome virus proliferation

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious and virulent infectious disease caused by the porcine reproductive and respiratory syndrome virus (PRRSV), which has substantial economic losses in the pig industry worldwide, and PRRSV attenuated vaccines and inactivated vaccines do have limitations in immune protection. The discovery of new antiviral targets has become a new research field. The proteomic studies have shown that the PRRSV NSP2 protein interacts with tripartite motif protein 4 (TRIM4), but it was still unknown whether TRIM4 regulates PRRSV infections. In this study, the TRIM4 gene from Marc-145 cells was cloned, and it was proved that TRIM4 overexpression inhibits PRRSV replication, whereas TRIM4 small-interfering-RNA knockdown resulted in increased virus titers. Mechanism investigation indicated that TRIM4 inhibits PRRSV replication through ubiquitination and degradation of the NSP2 protein. Protease inhibitor MG132 (carbobenzoxy-Leu-Leu-leucinal) attenuated the TRIM4-driven degradation of NSP2. Taken together, TRIM4 impairs PRRSV proliferation via ubiquitination and degradation of NSP2.

Inhibitory effect and mechanism of gelatin stabilized ferrous sulfide nanoparticles on porcine reproductive and respiratory syndrome virus

Background

The infection and spread of porcine reproductive and respiratory syndrome virus (PRRSV) pose a serious threat to the global pig industry, and inhibiting the viral infection process is a promising treatment strategy. Nanomaterials can interact with viruses and have attracted much attention due to their large specific surface area and unique physicochemical properties. Ferrous sulfide nanoparticles (FeS NPs) with the characteristics of high reactivity, large specific surface area, and low cost are widely applied to environmental remediation, catalysis, energy storage and medicine. However, there is no report on the application of FeS NPs in the antiviral field. In this study, gelatin stabilized FeS nanoparticles (Gel-FeS NPs) were large-scale synthesized rapidly by the one-pot method of co-precipitation of Fe²⁺ and S^2‒.

Results

The prepared Gel-FeS NPs exhibited good stability and dispersibility with an average diameter of 47.3 nm. Additionally, they were characterized with good biocompatibility and high antiviral activity against PRRSV proliferation in the stages of adsorption, invasion, and replication.

Conclusions

We reported for the first time the virucidal and antiviral activity of Gel-FeS NPs. The synthesized Gel-FeS NPs exhibited good dispersibility and biocompatibility as well as effective inhibition on PRRSV proliferation. Moreover, the Fe²⁺ released from degraded Gel-FeS NPs still displayed an antiviral effect, demonstrating the advantage of Gel-FeS NPs as an antiviral nanomaterial compared to other nanomaterials. This work highlighted the antiviral effect of Gel-FeS NPs and provided a new strategy for ferrous-based nanoparticles against PRRSV.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01281-4.

Molecular cloning and functional analysis of Macaca mulatta STING

Stimulator of interferon gene (STING), an adaptor molecule in the immune system, is involved in mediating the response to viral and bacterial infections, anti-tumor immunity, autoimmune diseases, and lipid metabolism. There have been reports on the cloning and function of STING in humans, pigs, chickens, and cats; however, STING has not been characterized in non-human primates or monkeys to date. Therefore, in this study, the rhesus macaque (Macaca mulata) STING gene was cloned, and we performed preliminary functional tests to examine its role in the interferon (IFN) pathway. The M. mulatta STING complementary DNA was 1140 bp in length and encoded 380 amino acid residues. Phylogenetic analysis showed that Homo sapiens and M. mulatta STING are closely related and clustered on the same branch. M. mulatta STING was confirmed to increase the promoter activities of IFN-β, nuclear factor-κB, and interferon-sensitive response element, and STING overexpression increased the mRNA levels of IFN-α, IFN-β, and interferon regulatory factor 3. Infection of Marc-145 cells with porcine reproductive and respiratory syndrome virus activated STING, and its expression increased along with increases in viral multiplicity of infection titer and time. Moreover, STING expression was time- and dose-dependently up-regulated by poly (I:C) and poly (dA:dT) treatments in Marc-145 cells. In summary, these results highlight STING as a vital immune system signal protein in the IFN pathway. This study provides a basis for understanding the immune characteristics of M. mulatta, and may have important implications for both monkey and human diseases.

Integration of Transcriptome and Proteome in Lymph Nodes Reveal the Different Immune Responses to PRRSV Between PRRSV-Resistant Tongcheng Pigs and PRRSV-Susceptible Large White Pigs

Porcine reproductive and respiratory syndrome (PRRS) is an infectious disease that seriously affects the swine industry worldwide. Understanding the interaction between the host immune response and PRRS virus (PRRSV) can provide insight into the PRRSV pathogenesis, as well as potential clues to control PRRSV infection. Here, we examined the transcriptome and proteome differences of lymph nodes between PRRSV-resistant Tongcheng (TC) pigs and PRRSV-susceptible Large White (LW) pigs in response to PRRSV infection. 2245 and 1839 differentially expressed genes (DEGs) were detected in TC and LW pigs upon PRRSV infection, respectively. Transcriptome analysis revealed genetic differences in antigen presentation and metabolism between TC pigs and LW pigs, which may lead to different immune responses to PRRSV infection. Furthermore, 678 and 1000 differentially expressed proteins (DEPs) were identified in TC and LW pigs, and DEPs were mainly enriched in the metabolism pathways. Integrated analysis of transcriptome and proteome datasets revealed antigen recognition capacity, immune activation, cell cycles, and cell metabolism are important for PRRSV clearance. In conclusion, this study provides important resources on transcriptomic and proteomic levels in lymph nodes for further revealing the interaction between the host immune response and PRRSV, which would give us new insight into molecular mechanisms related to genetic complexity against PRRSV.

Selection and validation of differentially expressed metabolic and immune genes in weaned Ghurrah versus crossbred piglets

In the present investigation, differentially expressed genes (DEGs) were studied using RNA sequencing (RNA-seq) technique in porcine peripheral blood mononuclear cells (PBMC) of weaned Ghurrah and crossbred piglets at 3-month age. Transcriptomic analysis was done using three different packages, namely, EBSeq, DESeq2, and edgeR, to identify the DEGs between Ghurrah and crossbred piglets. Total 7717 DEGs were commonly identified by all three packages, out of which 4151 genes found to be up-regulated, and 3566 genes were down-regulated. Functional annotation of these DEGs indicated metabolism as the most commonly enriched category followed by the immune response. Genes related to metabolism and growth were up-regulated in crossbred piglets as compared with Ghurrah piglets, whereas immunity-related genes were up-regulated in Ghurrah piglets elucidating the disease resistance nature of this indigenous breed over crossbred counterparts. Further, eight DEGs, namely, LRP-1, ADCY4, ERRFI1, LDHD, ARG1, OASL, MGARP, and S100A8, were validated by qRT-PCR in a separate set of biological samples and found to be in concordance with RNA-seq results. Finding in the present study provides insight into genes and their molecular mechanisms governing difference in growth performance between Ghurrah and crossbred pigs.

Bioinformatics analyses of significant genes, related pathways, and candidate diagnostic biomarkers and molecular targets in SARS-CoV-2/COVID-19

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) infection is a leading cause of pneumonia and death. The aim of this investigation is to identify the key genes in SARS-CoV-2 infection and uncover their potential functions. We downloaded the expression profiling by high throughput sequencing of GSE152075 from the Gene Expression Omnibus database. Normalization of the data from primary SARS-CoV-2 infected samples and negative control samples in the database was conducted using R software. Then, joint analysis of the data was performed. Pathway and Gene ontology (GO) enrichment analyses were performed, and the protein-protein interaction (PPI) network, target gene - miRNA regulatory network, target gene - TF regulatory network of the differentially expressed genes (DEGs) were constructed using Cytoscape software. Identification of diagnostic biomarkers was conducted using receiver operating characteristic (ROC) curve analysis. 994 DEGs (496 up regulated and 498 down regulated genes) were identified. Pathway and GO enrichment analysis showed up and down regulated genes mainly enriched in the NOD-like receptor signaling pathway, Ribosome, response to external biotic stimulus and viral transcription in SARS-CoV-2 infection. Down and up regulated genes were selected to establish the PPI network, modules, target gene - miRNA regulatory network, target gene - TF regulatory network revealed that these genes were involved in adaptive immune system, fluid shear stress and atherosclerosis, influenza A and protein processing in endoplasmic reticulum. In total, ten genes (CBL, ISG15, NEDD4, PML, REL, CTNNB1, ERBB2, JUN, RPS8 and STUB1) were identified as good diagnostic biomarkers. In conclusion, the identified DEGs, hub genes and target genes contribute to the understanding of the molecular mechanisms underlying the advancement of SARS-CoV-2 infection and they may be used as diagnostic and molecular targets for the treatment of patients with SARS-CoV-2 infection in the future.

Porcine reproductive and respiratory syndrome virus up-regulates sialoadhesin via IFN-STAT signaling to facilitate its infection

Porcine reproductive and respiratory syndrome (PRRS) has caused huge economic losses to global swine industry. Porcine sialoadhesin (poSn) was previously reported to be a putative receptor for the causative agent, PRRS virus (PRRSV). In the current study, we first observed that PRRSV infection up-regulated expression of poSn in a dose- and time-dependent manner. Subsequently, we found that PRRSV-triggered transcription of type I interferons (IFNs) was involved in poSn up-regulation through the IFN-signal transducer and activator of transcription (STAT) signaling cascade. Interestingly, poSn up-regulation was shown to promote PRRSV infection during post-entry process. Taken together, this work deepens our understanding of PRRSV pathogenesis and provides a novel idea on its establishment of persistent infection, which will be interesting to unravel the detailed mechanisms in the future.

Molecular cloning and functional characterization of porcine 2',5'-oligoadenylate synthetase 1b and its effect on infection with porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) has previously been shown to increase porcine 2'-5'-oligoadenylate synthase (OAS) 1a expression, but the specific role of porcine OAS1b (pOAS1b) in PRRSV replication remains unknown. In this study, we conducted sequence analysis of the porcine OAS1b gene and studied the effects of its overexpression or silencing on PRRSV replication. OAS1b, localized mainly in the cytoplasm, was found to contain conserved protein domains, such as the P-Loop and D-Box, indicating that its nucleotidyl transferase activity was complete and the antiviral effect depended on ribonuclease L (RNase L). OAS1b overexpression inhibited PRRSV replication, whereas small-interfering-RNA silencing of OAS1b resulted in increased virus titers. Additionally, OAS1b promoted expression of interferons as well as interferon-β promoter activity. These results lay the theoretical foundation for the development of new anti-PRRSV strategies.