Expression of IFN-λ1 from Congjiang pigs and its effect on anti-PRRSV proliferation

Porcine reproductive and respiratory syndrome virus infection induces microRNA novel-216 production to facilitate viral-replication by targeting MAVS 3´UTR

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused significant economic losses in the swine industry. In this study, the high-throughput sequencing, microRNAs (miRNAs) mimic, and lentivirus were used to screen for potential miRNAs that can promote PRRSV infection in porcine alveolar macrophages or Marc-145 cells. It was observed that novel-216, a previously unidentified miRNA, was upregulated through the p38 signaling pathway during PRRSV infection, and its overexpression significantly increased PRRSV replication. Further analysis revealed that novel-216 regulated PRRSV replication by directly targeting mitochondrial antiviral signaling protein (MAVS), an upstream molecule of type Ⅰ IFN that mediates the production and response of type Ⅰ IFN. The proviral function of novel-216 on PRRSV replication was abolished by MAVS overexpression, and this effect was reversed by the 3'UTR of MAVS, which served as the target site of novel-216. In conclusion, this study demonstrated that PRRSV-induced upregulation of novel-216 served to inhibit the production and response of typeⅠ IFN and facilitate viral replication, providing new insights into viral immune evasion and persistent infection.

Correlation Between MicroRNA by Extracellular Vesicle Mediated and Antiviral Effects of Interferon Omega in Feline Peripheral Blood

Feline interferon omega (IFN-ω) has been proven to have high antiviral activity; however, its in-depth antiviral effects remain unknown. Extracellular vesicles (EVs) have been demonstrated to participate in the regulation of the immune response pathway for the body through various active substances, especially through the microRNA (miRNA) carried by them. In this study, we isolated EVs from feline peripheral blood by differential centrifugation, and further found that the content of IFN-ω in EVs increased continuously within 24 h after IFN-ω treatment, and a large number of miRNAs were significantly downregulated in EVs within 12 h after IFN-ω treatment. These significantly differentially expressed miRNAs were important for regulating changes in antiviral cytokines. This study reveals for the first time the correlation between EVs-mediated miRNA in feline peripheral blood and IFN-ω on antiviral immune response, which may provide strong data support for the development of novel antiviral nanomedicine and the research of the antiviral effects of IFN-ω.

Isolation and characterization of the mink interferon-epsilon gene and its antiviral activity

The interferon (IFN) response is the first line of defense against viral invasion and thus plays a central role in the regulation of the immune response. IFN-epsilon (IFN-ε) is a newly discovered type I IFN that does not require viral induction, unlike other type I IFNs. IFN-ε is constitutively expressed in epithelial cells and plays an important role in mucosal immunity. In this study, we evaluated the biological activity of the mink-IFN (MiIFN)-ε gene in prokaryotic cells. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to evaluate IFN-ε expression in different mink tissues. MiIFN-ε was highly expressed in brain, lung, tracheal, kidney, intestinal, bladder, ovarian, and testis tissues. There was no significant difference in MiIFN-ε expression between female and male minks, except in the reproductive system. Expression of the small ubiquitin-like modifier (SUMO3)-MiIFN-ε fusion gene was induced by isopropylβ-d-thiogalactoside, and MiIFN-ε was collected after SUMO-specific protease digestion. We tested the antiviral activity of MiIFN-ε against vesicular stomatitis virus (VSV) in epithelial cells of feline kidney 81 (F81). We used qRT-PCR to analyze the expression of several IFN-stimulated genes (ISGs), including ISG15, 2'-5' oligoadenylate synthetase (2'-5'OAS1), and myxovirus resistance protein 1 (Mx1). Recombinant IFN-ε induced high ISG expression in F81 cells. Compared with those in the cell control group, expressions of ISG15, Mx1, and 2'-5' OAS1 in the VSV-GFP control, IFN-ε, and MiIFN-ε-inhibited VSV-GFP groups were significantly increased. Compared with those in the VSV-GFP control group, expressions of ISG15 and 2'-5' OAS1 in the IFN-ε and MiIFN-ε-inhibited VSV-GFP groups were significantly increased, and the differences were highly significant (p < 0.0001). IFN-ε played an indirect antiviral role. These findings lay the foundation for detailed investigation of IFN-ε in the future.

Antiviral activity of mink interferon alpha expressed in the yeast Pichia pastoris

Many viruses can cause infections in mink, including canine distemper virus, mink enteritis virus, and Aleutian disease virus. Current treatments are ineffective, and these infections are often fatal, causing severe economic losses. As antiviral drugs may effectively prevent and control these infections, recent research has increasingly focused on antiviral interferons. Herein, the gene encoding a mature mink interferon alpha (MiIFN-α) was synthesized according to the P. pastoris preference of codon usage and a recombinant plasmid, pPICZαA-MiIFN-α, was constructed. pPICZαA-MiIFN-α was linearized and transformed into the P. pastoris X33 strain, and zeocin-resistant transformants were selected. Protein expression was induced by methanol. SDS-PAGE and western blot analyses showed that a 25-kDa fusion protein was expressed in the culture supernatant. Antiviral activity of the expressed protein was determined using cytopathic effect inhibition (CPEI). The purified MiIFN-α significantly inhibited the cytopathic effect of vesicular stomatitis virus with a green fluorescent protein (VSV-GFP) in F81 feline kidney cells, with an antiviral activity of 6.4 × 10⁷ IU/mL; it also significantly inhibited MEV replication in F81 cells. MiIFN-α antiviral activity against VSV-GFP was significantly reduced on treatment with pH 4 and pH 10 conditions for 24 h (p < 0.01). Serum MiIFN-α concentrations in rat were measured using enzyme-linked immune-sorbent assay; MiIFN-α concentrations in rat serum peaked at ~36 h after injection. A high dose of MiIFN-α was safe for use. There were no significant differences in body temperature, tissue changes, and lymphocyte, total white blood cell, and central granulocyte counts between the injected and control groups (p > 0.05). These findings lay a foundation for the large-scale production of recombinant MiIFNs.