BackgroundNo clinically proven effective antiviral strategy exists for the epidemic Coronavirus Disease 2019 . MethodsWe conducted a prospective, randomized, controlled, open-label multicenter trial involving adult patients with COVID-19. Patients were randomly assigned in a 1:1 ratio to receive conventional therapy plus Umifenovir (Arbidol) (200mg*3/day) or Favipiravir (1600mg*2/first day followed by 600mg*2/day) for 10 days. The primary outcome was clinical recovery rate of Day 7. Latency to relief for pyrexia and cough, the rate of auxiliary oxygen therapy (AOT) or noninvasive mechanical ventilation (NMV) were the secondary outcomes. Safety data were collected for 17 days.

Autophagy plays an important role in cellular responses to pathogens. However, the impact of the autophagy machinery on classical swine fever virus (CSFV) infection is not yet confirmed. In this study, we showed that CSFV infection significantly increases the number of autophagy-like vesicles in the cytoplasm of host cells at the ultrastructural level. We also found the formation of 2 ubiquitin-like conjugation systems upon virus infection, including LC3-I/LC3-II conversion and ATG12–ATG5 conjugation, which are considered important indicators of autophagy. Meanwhile, high expression of ATG5 and BECN1 was detected in CSFV-infected cells; conversely, degradation of SQSTM1 was observed by immunoblotting, suggesting that CSFV infection triggered a complete autophagic response, most likely by the NS5A protein. Furthermore, by confocal immunofluorescence analysis, we discovered that both envelope protein E2 and nonstructural protein NS5A colocalized with LC3 and CD63 during CSFV infection. Examination by immunoelectron microscopy further confirmed the colocalization of both E2 and NS5A proteins with autophagosome-like vesicles, indicating that CSFV utilizes the membranes of these vesicles for replication. Finally, we demonstrated that alteration of cellular autophagy by autophagy regulators and shRNAs affects progeny virus production. Collectively, these findings provide strong evidence that CSFV infection needs an autophagy pathway to enhance viral replication and maturity in host cells.

Effective laboratory markers for the estimation of disease severity and predicting the clinical progression of coronavirus disease-2019 (COVID-19) is urgently needed. Laboratory tests, including blood routine, cytokine profiles and infection markers, were collected from 389 confirmed COV-ID-19 patients. The included patients were classified into mild (n = 168), severe (n = 169) and critical groups (n = 52). The leukocytes, neutrophils, infection biomarkers [such as C-reactive protein (CRP), procalcitonin (PCT) and ferritin] and the concentrations of cytokines [interleukin (IL)-2R, IL-6, IL-8, IL-10 and tumor necrosis factor (TNF)-α] were significantly increased, while lymphocytes were significantly decreased with increased severity of illness. The amount of IL-2R was positively correlated with the other cytokines and negatively correlated with lymphocyte number. The ratio of IL-2R to lymphocytes was found to be remarkably increased in severe and critical patients. IL-2R/lymphocytes were superior compared with other markers for the identification of COVID-19 with critical illness, not only from mild but also from severe illness. Moreover, the cytokine profiles and IL-2R/lymphocytes were significantly decreased in recovered patients, but further increased in disease-deteriorated patients, which might be correlated with the outcome of COVID-19. Lymphopenia and increased levels of cytokines were closely associated with disease severity. The IL-2R/lymphocyte was a prominent biomarker for early identification of severe COVID-19 and predicting the clinical progression of the disease.

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C-type lectins play key roles in pathogen recognition, innate immunity, and cell-cell interactions. Here, we report a new C-type lectin (C-type lectin 1) from the shrimp Litopenaeus vannamei (LvCTL1), which has activity against the white spot syndrome virus (WSSV). LvCTL1 is a 156-residue polypeptide containing a C-type carbohydrate recognition domain with an EPN (Glu 99 -Pro 100 -Asn 101 ) motif that has a predicted ligand binding specificity for mannose. Reverse transcription-PCR analysis revealed that LvCTL1 mRNA was specifically expressed in the hepatopancreas of L. vannamei. Recombinant LvCTL1 (rLvCTL1) had hemagglutinating activity and ligand binding specificity for mannose and glucose. rLvCTL1 also had a strong affinity for WSSV and interacted with several envelope proteins of WSSV. Furthermore, we showed that the binding of rLvCTL1 to WSSV could protect shrimps from viral infection and prolong the survival of shrimps against WSSV infection. Our results suggest that LvCTL1 is a mannose-binding C-type lectin that binds to envelope proteins of WSSV to exert its antiviral activity. To our knowledge, this is the first report of a shrimp C-type lectin that has direct anti-WSSV activity.

Tiger frog virus (TFV), in the genusRanavirus of the family Iridoviridae, causes high mortality of cultured tiger frog tadpoles in China. To explore the cellular entry mechanism of TFV, HepG2 cells were treated with drugs that inhibit the main endocytic pathways. We observed that TFV entry was inhibited by NH 4 Cl, chloroquine, and bafilomycin, which can all elevate the pH of acidic organelles. In contrast, TFV entry was not influenced by chlorpromazine or overexpression of a dominant-negative form of Esp15, which inhibit the assembly of clathrin-coated pits. These results suggested that TFV entry was not associated with clathrinmediated endocytosis, but was related to the pH of acidic organelles. Subsequently, we found that endocytosis of TFV was dependent on membrane cholesterol and was inhibited by the caveolin-1 scaffolding domain peptide. Dynamin and actin were also required for TFV entry. In addition, TFV virions colocalized with the cholera toxin subunit B, indicating that TFV enters as caveola-internalized cargo into the Golgi complex. Taken together, our results demonstrated that TFV entry occurs by caveola-mediated endocytosis with a pH-dependent step. This atypical caveola-mediated endocytosis is different from the clathrin-mediated endocytosis of frog virus 3 (FV3) by BHK cells, which has been recognized as a model for iridoviruses. Thus, our work may help further the understanding of the initial steps of iridovirus infection in lower vertebrates.

Background: In addition to supportive therapy, antiviral therapy is an effective treatment for coronavirus disease 2019 (COVID-19).Objective: To compare the efficacy and safety of favipiravir and umifenovir (Arbidol) to treat COVID-19 patients.Methods: We conducted a prospective, randomized, controlled, open-label multicenter trial involving adult patients with COVID-19. Enrolled patients with initial symptoms within 12 days were randomly assigned in a 1:1 ratio to receive conventional therapy plus Arbidol (200 mg*3/day) or favipiravir (1600 mg*2/first day followed by 600 mg*2/day) for 7 days. The primary outcome was the clinical recovery rate at day 7 of drug administration (relief for pyrexia and cough, respiratory frequency ≤24 times/min; oxygen saturation ≥98%). Latency to relief for pyrexia and cough and the rate of auxiliary oxygen therapy (AOT) or noninvasive mechanical ventilation (NMV)/mechanical ventilation (MV) were the secondary outcomes. Safety data were collected for 17 days.Results: A total of 240 enrolled COVID-19 patients underwent randomization; 120 patients were assigned to receive favipiravir (116 assessed), and 120 patients were assigned to receive Arbidol (120 assessed). The clinical recovery rate at day 7 of drug administration did not significantly differ between the favipiravir group (71/116) and Arbidol group (62/120) (p = 0.1396, difference in recovery rate: 0.0954; 95% CI: −0.0305∼0.2213). Favipiravir contributed to relief for both pyrexia (difference: 1.70 days, p < 0.0001) and cough (difference: 1.75 days, p < 0.0001). No difference was observed in the AOT or NMV/MV rate (both p > 0.05). The most frequently observed favipiravir-associated adverse event was increased serum uric acid (16/116, OR: 5.52, p = 0.0014).Conclusion: Among patients with COVID-19, favipiravir, compared to Arbidol, did not significantly improve the clinical recovery rate at day 7. Favipiravir significantly improved the latency to relieve pyrexia and cough. Adverse effects caused by favipiravir are mild and manageable.

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