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Backgrounds While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection presents with mild or no symptoms in most cases, a significant number of patients become critically ill. Remdesivir has been approved for the treatment of coronavirus disease 2019 (COVID-19) in several countries, but its use as monotherapy has not substantially lowered mortality rates. Because agents from traditional Chinese medicine (TCM) have been successfully utilized to treat pandemic and endemic diseases, we designed the current study to identify novel anti-SARS-CoV-2 agents from TCM. Materials and methods We initially used an antivirus-induced cell death assay to screen a panel of herbal extracts. The inhibition of the viral infection step was investigated through a time-of-drug-addition assay, whereas a plaque reduction assay was carried out to validate the antiviral activity. Direct interaction of the candidate TCM compound with viral particles was assessed using a viral inactivation assay. Finally, the potential synergistic efficacy of remdesivir and the TCM compound was examined with a combination assay. Results The herbal medicine Perilla leaf extract (PLE, approval number 022427 issued by the Department of Health and Welfare of Taiwan) had EC50 of 0.12 ± 0.06 mg/mL against SARS-CoV-2 in Vero E6 cells – with a selectivity index of 40.65. Non-cytotoxic PLE concentrations were capable of blocking viral RNA and protein synthesis. In addition, they significantly decreased virus-induced cytokine release and viral protein/RNA levels in the human lung epithelial cell line Calu-3. PLE inhibited viral replication by inactivating the virion and showed additive-to-synergistic efficacy against SARS-CoV-2 when used in combination with remdesivir. Conclusions Our results demonstrate for the first time that PLE is capable of inhibiting SARS-CoV-2 replication by inactivating the virion. Our data may prompt additional investigation on the clinical usefulness of PLE for preventing or treating COVID-19., Graphical abstract Image 1

The chikungunya virus (CHIKV) is a mosquito-borne virus that belongs to the genus Alphavirus, family Togaviridae. It is the cause of chikungunya fever in humans, which presents a serious global threat due to its high rate of contagion. The clinical symptoms of CHIKV include fever and persistent, severe arthritis. Micafungin has broad-spectrum fungicidal activity against Candida spp. is a promising echinocandin that was recently approved by the U.S. Food and Drug Administration (FDA) and has demonstrated activity against Candida and Aspergillus. Recent studies have demonstrated the antiviral activity of micafungin; however, the inhibitory effects against CHIKV have yet to be investigated. Our objectives in this study were to explore the antiviral effects of micafungin on CHIKV infection and to elucidate the potential molecular mechanisms of inhibition. We determined that micafungin has the ability to counter CHIKV-induced cytopathic effects. We further discovered that micafungin limits virus replication, release, cell-to-cell transmission, and also slightly affected virus stability during high doses treatment. The efficacy of micafungin was further confirmed against two clinical isolates of CHIKV and two alphaviruses: Sindbis virus (SINV) and Semliki Forest virus (SFV). Our findings suggest that micafungin has considerable potential as a novel inhibitor against the viral replication, and intracellular and extracellular transmission of CHIKV, and has a little effect on virus stability. Our findings also suggest that micafungin could have curative effects on other alphavirus infections.

In April 2013, a bomb-threat incident occurred on the Taiwan high-speed railway. Two suspects claimed to have placed explosive devices on a high-speed train and outside a lawmaker’s office. Afterward, the Criminal Investigation Bureau also found several bottles in the main suspect’s apartment labeled “botulinum toxin.” The Institute of Preventive Medicine was entrusted by the Institute of Forensic Medicine, Ministry of Justice, to verify whether the bottles contained botulinum neurotoxin (BoNT). Three different analyses, including rapid detection strips, toxin neutralization tests, and bacterial culture, were processed. The results provided conclusive evidence that botulinum neurotoxin type A (BoNT/A) was present in the samples. This study demonstrated that the BoNT/A strip assay is an excellent method for BoNT/A detection, and has potential use as an early warning tool in screening of food products for botulinum toxins.

The E5a gene of human papillomavirus type 11 (HPV-11) is a transforming oncogene. In this study, we investigated the mechanism of E5a induced transformation. Our results show that the expression of c-jun and junB, but not junD, was activated by HPV-11 E5a in NIH 3T3 cells and human epidermal keratinocytes. However, the expression of c-fos was activated by E5a in NIH 3T3 cells, but not in keratinocytes. We further investigated the mechanism of c-jun and junB induction by E5a. The amount of c-jun and junB RNAs correlated with the amount of E5a RNA in the heavy metal inducible system. E5a constitutively activated the expression of c-jun and junB at the initiation of transcription level. In addition, analyses of the effect of serum on c-jun expression in E5a transformed human epidermal keratinocytes show that EGF might have a stimulatory effect on c-jun gene expression in E5a expressing keratinocytes.

A recombinant plasmid, pYL-1, containing a tyrosinase gene whose expression is under the control of a phage T5 promoter and 2 lac operators, was constructed. Escherichia coli JM109 harboring pYL-1 was used for production of bacterial melanin. A simple procedure for the isolation and purification of melanin was developed. The ultraviolet (UV)-visible light absorption spectra of melanin prepared by chemical synthesis and derived from different organisms, including bacteria, a plant and an animal source, were determined. Melanins produced by both bacteria and chemical synthesis showed a steady increase of absorption at wavelengths of UV light ranging from approximately 200-400 nm, while melanin derived either from plant or animal sources showed an additional discrete absorption peak at wavelength 280 nm upon a similar steady increase of absorption. This additional absorption peak could be due to the presence of protein-bound melanins in animal and plant sources while a free form of melanin was obtained from bacteria and chemical synthesis. Analysis of the effect of bacterial melanin on the activity of antibiotics against E. coli revealed that the activities of polymyxin B, kanamycin, tetracycline, and ampicillin were markedly reduced in the presence of melanin, whereas the activity of norfloxacin was not affected. The reduction of the antibacterial activity may result directly from the interaction of antibiotics with melanin. However, the mechanism of this interaction remains to be demonstrated.

We have previously shown that the E5a gene of human papilloma virus type 11 (HPV-11/HPV-6c) is a transforming oncogene. In order to dissect the biological consequences of E5a gene expression we utilized the lac operator/repressor system to manipulate E5a gene expression. Cells were cotransfected with the lac repressor gene and the E5a gene that had been inserted downstream of a simian virus 40 (SV40) promoter containing the lac operator sequence. The expression of E5a gene could therefore be repressed by binding of lac repressor to the lac operator sequence in proximity to this SV40 regulatory region. The transfected cells were cultured in the presence of the inducer IPTG and under G418 selection. IPTG derepressed E5a gene expression by binding to the repressor and reducing its affinity for the lac operator sequence. In these studies, we found that E5a-transformed cells still maintained the transformed phenotype as judged by growth density, cell morphology and anchorage-independent growth when E5a gene expression was repressed. We also found that c-jun expression was induced 3 h after E5a expression was induced by IPTG and c-jun expression was not shut down after repression of E5a expression. This is the first demonstration that the E5a gene of HPV-11 initiates transformation of NIH 3T3 cells but is dispensable for maintenance of the transformed phenotype.