Characterization of the Ictalurid herpesvirus 1 immediate-early gene ORF24 and its potential role in transcriptional regulation in yeast.

Herpesviruses adhere to a precise temporal expression model in which immediate-early (IE) genes play a crucial role in regulating the viral life cycle. However, there is a lack of functional research on the IE genes in Ictalurid herpesvirus 1 (IcHV-1). In this study, we identified the IcHV-1 ORF24 as an IE gene via a metabolic inhibition assay, and subcellular analysis indicated its predominant localisation in the nucleus. To investigate its function, we performed yeast reporter assays using an ORF24 fusion protein containing the Gal4-BD domain and found that BD-ORF24 was able to activate HIS3/lacZ reporter genes without the Gal4-AD domain. Our findings provide concrete evidence that ORF24 is indeed an IE gene that likely functions as a transcriptional regulator during IcHV-1 infection. This work contributes to our understanding of the molecular mechanisms underlying fish herpesvirus IE gene expression.

Proprotein convertase cleavage of Ictalurid herpesvirus 1 spike-like protein ORF46 is modulated by N-glycosylation.

Viral spike proteins undergo a special maturation process that enables host cell receptor recognition, membrane fusion, and viral entry, facilitating effective virus infection. Here, we investigated the protease cleavage features of ORF46, a spike-like protein in Ictalurid herpesvirus 1 (IcHV-1) sharing similarity with spikes of Nidovirales members. We noted that during cleavage, full-length ORF46 is cleaved into ∼55-kDa and ∼100-kDa subunits. Moreover, truncation or site-directed mutagenesis at the recognition sites of proprotein convertases (PCs) abolishes this spike cleavage, highlighting the crucial role of Arg506/Arg507 and Arg668/Arg671 for the cleavage modification. ORF46 cleavage was suppressed by specific N-glycosylation inhibitors or mutation of its specific N-glycosylation sites (N192, etc.), suggesting that glycoprotein ORF46 cleavage is modulated by N-glycosylation. Notably, PCs and N-glycosylation inhibitors exhibited potent antiviral effects in host cells. Our findings, therefore, suggested that PCs cleavage of ORF46, modulated by N-glycosylation, is a potent antiviral target for fish herpesviruses.

Kaempferol is a novel antiviral agent against channel catfish virus infection through blocking viral attachment and penetration in vitro.

Channel catfish virus (CCV, Ictalurid herpesvirus 1) is the causative pathogen of channel catfish virus disease, which has caused high mortality and substantial economic losses in the catfish aquaculture industry. Due to the lack of licensed prophylactic vaccines and therapeutic drugs, the prevention and control of CCV infection seem to remain stagnant. Active compounds from medicinal plants offer eligible sources of pharmaceuticals and lead drugs to fight against endemic and pandemic diseases and exhibit excellent effect against viral infection. In this study, we evaluated the antiviral ability of 12 natural compounds against CCV with cell models in vitro and found kaempferol exhibited the strongest inhibitory compound against CCV infection among all the tested compounds. Correspondingly, kaempferol decreased transcription levels of viral genes and the synthesis of viral proteins, as well as reduced proliferation and release of viral progeny, the severity of the CPE induced by CCV in a dose-dependent manner, based on quantitative real-time PCR (RT-qPCR), western blotting, viral cytopathic effects (CPE) and viral titer assessment. Moreover, time-of-drug-addition assays, virus attachment, and penetration assays revealed that kaempferol exerted anti-CCV activity probably by blocking attachment and internalization of the viral entry process. Altogether, the present results indicated that kaempferol may be a promising candidate antiviral agent against CCV infection, which shed light on the development of a novel and potent treatment for fish herpesvirus infection.

Heparan sulfate is the attachment factor associated with channel catfish virus infection on host cells.

Channel catfish virus (CCV; family Alloherpesviridae) infects channel catfish, causing great harm to aquaculture fisheries and economic development. Attachment is the first step in viral infection and relies on the interaction of virions with components of the extracellular matrix (ECM). The present study aimed to explored the role of the main three ECM components in CCV attachment. Western blotting and quantitative real-time PCR analysis showed that neither collagen nor hyaluronic acid treatments had significant effects on CCV attachment. When exogenous heparin was used as a competitive inhibitor, the adhesion of heparin sodium salt to CCV was dose-dependent. When the concentration of heparin sodium salt was 10 mg/mL, the inhibitory effect on CCV infection of channel catfish ovary (CCO/BB) cells was more than 90%. Heparinase I could significantly prevent CCV attachment by digesting heparan sulfate on the cell surface, and both heparin sodium salt and heparinase I could dose-dependently reduce CCV titers, suggesting that heparin plays an important role in CCV attachment. In addition, the binding experiments between heparin-agarose beads and virions showed that CCV virions could specifically bind to heparin in a dose-dependent manner. The above results suggested that heparan sulfate might be an attachment factor involved in CCV infection of CCO/BB cells. These results increase our understand of the attachment mechanism of CCV and lay the foundation for further research on antiviral drugs.

[Combined chemotherapy of weekly paclitaxel and ifosfamide in the treatment of 23 patients with advanced non-small cell lung cancer].

BACKGROUND: To evaluate the efficacy and safety of weekly paclitaxel and ifosfamide in the treatment of advanced non-small cell lung cancer. METHODS: Twenty-three patients with advanced non-small cell lung cancer received paclitaxel 50-65 mg/m² IV weekly on days 1, 8, 15, and IFO 1.3 g/m² IV on days 2-4. The schedule was repeated every 28 days for two or three cycles as a course. RESULTS: One patient had complete response and eight had partial response. Eleven patients had stable disease and three had progressive disease. The overall response rate was 39.1%. Twenty patients were followed-up. The 1-year survival was 40%(8/20) and the median survival duration was 8.9 months. The main toxicities were hematological toxicity (leukopenia, 69.6%, 16/23) and nausea/vomiting (47.8%, 11/23). CONCLUSIONS: Combined chemotherapy of weekly paclitaxel and ifosfamide is a good regimen for advanced non-small cell lung cancer with good efficacy and well-tolerated side effects.