Fangchinoline inhibits the PEDV replication in intestinal epithelial cells via autophagic flux suppression

Advances research in porcine enteric coronavirus therapies and antiviral drugs

The porcine enteric coronaviruses (PECs) currently reported include porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), transmissible gastroenteritis virus (TGEV), and swine acute diarrhea syndrome coronavirus (SADS-CoV). In the absence of effective treatment, they can cause similar clinical characteristics including weight loss, sleepiness, vomiting, anorexia and fatal diarrhea in neonatal piglets, resulting in significant economic losses to the global pig industry. Although many studies on drugs for treating and combating PECs have been issued. There are still no specific drug targeting PECs and used in clinical production. Therefore, it is necessary to sort out and summarize the research on the treatment and anti PECs drugs, and further development of low toxicity and high efficiency drugs is needed. Here, we review the latest progress of anti PECs drugs, focus on the mechanism of anti PECs reaction of drug components, and try to clarify new strategies for effective control and elimination of PECs. These comprehensive and profound insights will help to further investigate, prevent and control the transmission of PECs infection.

Bis-benzylisoquinoline alkaloids inhibit African swine fever virus internalization and replication by impairing late endosomal/lysosomal function

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a highly infectious disease afflicting domestic pigs and wild boars. It exhibits an alarming acute infection fatality rate of up to 100%. Regrettably, no commercial vaccines or specific drugs for combating this disease are currently available. This study evaluated the anti-ASFV activities in porcine alveolar macrophages, 3D4/21 cells, and PK-15 cells of four bis-benzylisoquinoline alkaloids (BBAs): cepharanthine (CEP), tetrandrine, fangchinoline, and iso-tetrandrine. Furthermore, we demonstrated that CEP, which exhibited the highest selectivity index (SI = 81.31), alkalized late endosomes/lysosomes, hindered ASFV endosomal transport, disrupted virus uncoating signals, and thereby inhibited ASFV internalization. Additionally, CEP disrupted ASFV DNA synthesis, leading to the inhibition of viral replication. Moreover, berbamine was labeled with NBD to synthesize a fluorescent probe to study the cellular location of these BBAs. By co-staining with Lyso-Tracker and lysosome-associated membrane protein 1, we demonstrated that BBAs target the endolysosomal compartments for the first time. Our data together indicated that BBAs are a class of natural products with significant inhibitory effects against ASFV infection. These findings suggest their potential efficacy as agents for the prevention and control of ASF, offering valuable references for the identification of potential drug targets.IMPORTANCEThe urgency and severity of African swine fever (ASF) underscore the critical need for effective interventions against this highly infectious disease, which poses a grave threat to domestic pigs and wild boars. Our study reveals the potent anti-African swine fever virus (ASFV) efficacy of bis-benzylisoquinoline alkaloids (BBAs), particularly evident in the absence of progeny virus production under a 5 µM concentration treatment. The structural similarity among cepharanthine, tetrandrine, fangchinoline, and iso-tetrandrine, coupled with their analogous inhibitory stages and comparable selectivity indexes, strongly suggests a shared antiviral mechanism within this drug category. Further investigation revealed that BBAs localize to lysosomes and inhibit the internalization and replication of ASFV by disrupting the endosomal/lysosomal function. These collective results have profound implications for ASF prevention and control, suggesting the potential of the investigated agents as prophylactic and therapeutic measures. Furthermore, our study offers crucial insights into identifying drug targets and laying the groundwork for innovative interventions.

Isolation of Limosilactobacillus mucosae G01 with inhibitory effects on porcine epidemic diarrhea virus in vitro from Bama pig gastroenteritis

Porcine epidemic diarrhea virus (PEDV) is responsible for causing fatal watery diarrhea in piglets, resulting in significant economic losses within the pig farming industry. Although vaccination is currently employed as a preventive measure, certain vaccines do not provide complete protection against PEDV field strains. Probiotics present a promising alternative due to their ability to regulate intestinal flora, enhance host immunity, and improve resistance against pathogenic microorganisms. We isolated six lactic acid bacteria (LAB) from the fecal microorganisms of Bama pigs, compared to Limosilactobacillus mucosae DSM13345 of the same genus in which Limosilactobacillus mucosae G01 (L. mucosae G01) proved to have a potent anti-PEDV effect. In a comprehensive manner, L. mucosae G01 significantly augmented the phosphorylation of IRF3 in IPEC-J2 cells, resulting in the induction of interferons (IFN α, IFN β, IFN λ1, and IFN λ3) and subsequent upregulation of interferon-stimulated genes (ISGs) (MX1, MX2, OAS1, and ZAP) in a dose-dependent fashion, consequently leading to the mitigation of PEDV replication. These findings underscore the promising prospects of L. mucosae G01 as a naturally derived substitute for combating PEDV and other enteric coronavirus infections.

Fangchinoline Inhibits African Swine Fever Virus Replication by Suppressing the AKT/mTOR/NF-κB Signaling Pathway in Porcine Alveolar Macrophages

African swine fever (ASF), caused by the African swine fever virus (ASFV), is one of the most important infectious diseases that cause high morbidity and mortality in pigs and substantial economic losses to the pork industry of affected countries due to the lack of effective vaccines. The need to develop alternative robust antiviral countermeasures, especially anti-ASFV agents, is of the utmost urgency. This study shows that fangchinoline (FAN), a bisbenzylisoquinoline alkaloid found in the roots of Stephania tetrandra of the family Menispermaceae, significantly inhibits ASFV replication in porcine alveolar macrophages (PAMs) at micromolar concentrations (IC50 = 1.66 µM). Mechanistically, the infection of ASFV triggers the AKT/mTOR/NF-κB signaling pathway. FAN significantly inhibits ASFV-induced activation of such pathways, thereby suppressing viral replication. Such a mechanism was confirmed using an AKT inhibitor MK2206 as it inhibited AKT phosphorylation and ASFV replication in PAMs. Altogether, the results suggest that the AKT/mTOR pathway could potentially serve as a treatment strategy for combating ASFV infection and that FAN could potentially emerge as an effective novel antiviral agent against ASFV infections and deserves further in vivo antiviral evaluations.

In vitro suppression of porcine epidemic diarrhea virus by Panax notoginseng saponins: assessing antiviral potential

Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea and high mortality in neonatal suckling piglets, leading to significant economic losses to the swine industry. Panax notoginseng saponins (PNS) are bioactive extracts derived from the P. notoginseng plant. In this study, we investigated the anti-PEDV effect of PNS by employing various methodologies to assess their impact on PEDV in Vero cells. Using a CCK-8 (Cell Counting Kit-8) assay, we found that PNS had no significant cytotoxicity below the concentration of 128 µg/mL in Vero cells. Using immunofluorescence assays (IFAs), an enzyme-linked immunosorbent assay (ELISA), and plaque formation assays, we observed a dose-dependent inhibition of PEDV infection by PNS within 24-48 hours postinfection. PNS exerts its anti-PEDV activity specifically at the genome replication stage, and mRNA-seq analysis demonstrated that treatment with PNS resulted in increased expression of various genes, including IFIT1 (interferon-induced protein with tetratricopeptide repeats 1), IFIT3 (interferon-induced protein with tetratricopeptide repeats 3), CFH (complement factor H), IGSF10 (immunoglobulin superfamily member 10), ID2 (inhibitor of DNA binding 2), SPP1 (secreted phosphoprotein 1), PLCB4 (phospholipase C beta 4), and FABP4 (fatty acid binding protein 4), but it resulted in decreased expression of IL1A (interleukin 1 alpha), TNFRSF19 (TNF receptor superfamily member 19), CDH8 (cadherin 8), DDIT3 (DNA damage inducible transcript 3), GADD45A (growth arrest and DNA damage inducible alpha), PTPRG (protein tyrosine phosphatase receptor type G), PCK2 (phosphoenolpyruvate carboxykinase 2), and ADGRA2 (adhesion G protein-coupled receptor A2). This study provides insights into the potential mechanisms underlying the antiviral effects of PNS. Taken together, the results suggest that the PNS might effectively regulate the defense response to the virus and have potential to be used in antiviral therapies.