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Autophagy is a conserved intracellular degradation process that plays an active role in plant response to virus infections. Here we report that geminiviruses counteract activated autophagy-mediated antiviral defense in plant cells through the C2 proteins they encode. We found that, in Nicotiana benthamiana plants, tomato leaf curl Yunnan virus (TLCYnV) infection upregulated the transcription levels of autophagy-related genes (ATGs). Overexpression of NbATG5, NbATG7, or NbATG8a in N. benthamiana plants decreased TLCYnV accumulation and attenuated viral symptoms. Interestingly, transgenic overexpression of NbATG7 promoted the growth of N. benthamiana plants and enhanced plant resistance to TLCYnV. We further revealed that the C2 protein encoded by TLCYnV directly interacted with the ubiquitin-activating domain of ATG7. This interaction competitively disrupted the ATG7-ATG8 binding in N. benthamiana and Solanum lycopersicum plants, thereby inhibiting autophagy activity. Furthermore, we uncovered that the C2-mediated autophagy inhibition mechanism was conserved in three other geminiviruses. In summary, we discovered a novel counter-defensive strategy employed by geminiviruses that enlists their C2 proteins as disrupters of ATG7-ATG8 interactions to defeat antiviral autophagy., (© 2023 Institute of Botany, Chinese Academy of Sciences.)

Type I interferons (IFNs) are critical cytokines for the establishment of antiviral status in fish, amphibian, avian and mammal, but the knowledge on type I IFNs is rather limited in reptile. In this study, seven type I IFN genes, designed as IFN1 to IFN7, were identified from a reptile species, the Chinese soft-shelled turtle (Pelodiscus sinensis). These identified type I IFNs have relatively low protein identity, when compared with those in human and chicken; but they possess conserved cysteines, predicted multi-helix structure and N-terminal signal peptide. The Chinese soft-shelled turtle IFN1 to IFN5 have two exons and one intron, but IFN6 and IFN7 are the single-exon genes. Chinese soft-shelled turtle type I IFNs are located respectively on the two conserved reptile-bird loci, named as Locus a and Locus c, and are clustered into the four of the five reptile-bird groups (named as Groups I-V) based on phylogenetic evidence, due to the lack of IFNK in the turtle. Moreover, the Chinese soft-shelled turtle type I IFNs can be induced by soft-shelled turtle iridovirus (STIV) infection and show antiviral activity in soft-shelled turtle artery (STA) cells, except IFN6. In addition, due to the difference in genome organizations, such as the number of exons and introns of type I IFN genes from fish to mammal, the definition and evolution of 'intronless' type I IFN genes were discussed in lineages of vertebrates. Thus, the finding of type I IFNs on two different loci in P. sinensis sheds light on the evolution of type I IFN genes in vertebrates., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The enzyme 2'-5'-oligoadenylate synthetase (OAS) is an antiviral protein induced by interferons (IFNs), which plays an important role in IFN-mediated antiviral signaling pathway. In this study, the OAS of Chinese Giant Salamander, Andrias davidianus (AdOAS) was identified for the first time, and the expression profiles in vivo and the antiviral activities in vitro were investigated. The open reading frame (ORF) of AdOAS gene is 1185 bp in length, encoding a putative protein of 394 amino acids, in which a Nucleotidyltransferase (NTase) domain (40-143 aa) and a conserved OAS1 C superfamily domain (165-341 aa) are included. qRT-PCR analysis revealed a broad expression of AdOAS in vivo, with the highest expression level in intestine and heart. After infection with Chinese giant salamander iridovirus (GSIV), the mRNA level of AdOAS in liver increased significantly at 24 h and 48 h post infection and reached the peak at 72 h compared with the control group. The AdOAS mRNA level in kidney increased slightly at 6 h and 12 h post infection, declined to the initial level at 24 h and peaked at 48 h post infection, while in spleen it was slightly up-regulated at 6 h, inhibited at 12 h, 24 h and 48 h, and then significantly increased to the peak at 72 h post infection. In vitro, AdOAS mRNA level in Chinese giant salamander muscle (GSM) cells was not noticeably up-regulated until 24 h and then peaked at 48 h post GSIV infection. In antiviral activity test, the mRNA transcription and protein level of virus major capsid protein (MCP) in AdOAS over-expressed cells was significantly reduced compared with that in control cells by qRT-PCR and western blot analysis. In addition, ddPCR results showed that lower MCP gene copy was found in AdOAS over-expressed cells compared with the control group. These results collectively suggest that AdOAS plays a crucial role against GSIV infection in Chinese giant salamander, and provide a solid base for the further studies on the mechanism of immune defense and the control of the disease in this animal., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A filamentous actinomycete, designated strain ZX01(T), was isolated from forest soil around Kanas Lake of China. A polyphasic taxonomic study was carried out to establish the status of strain ZX01(T). Chemical and morphological properties of the isolate were similar to those of species of the genus Streptomyces. Analysis of the almost complete 16S rRNA gene sequence placed strain ZX01(T) in the genus Streptomyces where it formed a distinct phyletic line with recognized species of this genus. The strain exhibited the highest sequence similarities to Streptomyces lavendofoliae NBRC 12882(T) (99.1%), S. luridus NBRC 12793(T) (99.0%), S. lavendulocolor NBRC 12881(T) (99.0%), S. gobitricini NBRC 15419(T) (99.0%), and S. roseolilacinus NBRC 12815(T) (98.9%). Low DNA-DNA relatedness values of 54.0, 50.0, 60.0, 66.7, and 50.4%, respectively, were found between strain ZX01(T) and corresponding strains above. A number of phenotypic properties also enabled the isolate to be differentiated from related species of the genus Streptomyces. Therefore, it is proposed that strain ZX01(T) should be classified as the type strain of a novel species in the genus Streptomyces, Streptomyces kanasensis sp. nov. The type strain is ZX01(T) (= CGMCC 4893(T) =JCM 30232(T)).

Catharanthus roseus is a medicinal plant belonging to the family Apocynaceae which produces terpenoid indole alkaloids (TIAs) of high medicinal importance. Indeed, a number of activities like antidiabetic, bactericide and antihypertensive are linked to C. roseus. Nevertheless, the high added value of this plant is based on its enormous pharmaceutical interest, producing more than 130 TIAs, some of which exhibit strong pharmacological activities. The most striking biological activity investigated has been the antitumour effect of dimeric alkaloids such as anhydrovinblastine, vinblastine and vincristine which are already in pre-, clinical or in use. The great pharmacological importance of these indole alkaloids, contrasts with the small amounts of them found in this plant, making their extraction a very expensive process. To overcome this problem, researches have looked for alternative sources and strategies to produce them in higher amounts. In this sense, intensive research on the biosynthesis of TIAs and the regulation of their pathways has been developed with the aim to increase by biotechnological approaches, the production of these high added value compounds. This review is focused on the different strategies which improve TIA production, and in the analysis of the beneficial effects that these compounds exert on human health.

Two new rubrolides, rubrolides R (1) and S (2), were isolated from the fermentation broth of the marine-derived fungus Aspergillus terreus OUCMDZ-1925. Their structures were elucidated on the basis of spectroscopic analysis and X-ray single crystal diffraction. Compound 1 showed comparable or superior antioxidation against 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radicals to those of trolox and ascorbic acid with an IC₅₀ value of 1.33 mM. Compound 2 showed comparable or superior anti-influenza A (H1N1) virus activity to that of ribavirin with an IC₅₀ value of 87.1 μM. Both compounds 1 and 2 showed weak cytotoxicity against the K562 cell line with IC₅₀ values of 12.8 and 10.9 μM, respectively.

Context: Insects are a large, unexplored and unexploited source of potentially useful compounds for modern medicine. The larvae of the housefly (Musca domestica) have been used to study immune-induced molecules because they can survive in pathogenic environments., Objective: The antiviral activity of a protein-enriched fraction (PEF) from the larvae of the housefly was evaluated in vitro and the possible antiviral mechanism was studied., Materials and Methods: PEF was isolated from the larvae of the housefly. The cytotoxicity of PEF was detected by the MTT assay. The in vitro antiviral activity of PEF against influenza virus was investigated. PEF was incubated with the virus and its target cells under various conditions, and its antiviral effects were examined by reduction in virus yield in cell cultures. Experiments with ribavirin were performed in parallel under the same conditions., Results: The results indicated that PEF had minimal cytotoxicity against MDCK cells and the CC₅₀ value was calculated to be 284.45 μg/ml. The antiviral results showed the loss of infectious capacity was more than two log (2) units in cell cultures compared with virus control. The effect of PEF was direct virucidal activity and the interference on the adsorption of cell and virus. The antiviral mechanism of PEF is different from ribavirin., Conclusion: The results indicate that PEF showed strong antiviral activity against influenza virus at a very early stage of the interaction with virus particles or their entry into the cells. PEF has a great potential as a resource of healthy products.

Recently, a highly dangerous bird flu has infected over 130 patients in China, and the outbreak was attributed to a novel avian-origin H7N9 virus. Here, we performed a systematic analysis of the virus. We clarified the controversial viewpoint on neuraminidase (NA) origin and confirmed it was reassorted from Korean wild birds with higher confidence, whereas common ancestors of pathogenic H7N9 genes existed only one or two years ago. Further analysis of NA sequences suggested that most variations are not drug resistant and current drugs are still effective for the therapy. We also identified a potentially optimal 9-mer epitope, which can be helpful for vaccine development. The interaction of hemagglutinin (HA) and human receptor analog was confirmed by structural modeling, while NA might influence cellular processes through a PDZ-binding motif. A simplified virus infection model was proposed. Taken together, our studies provide a better understanding of the newly reassorted H7N9 viruses.

The retroviral restriction factor TRIMCyp, derived from the TRIM5 gene, blocks replication at a postentry step. TRIMCyp has so far been found in four species of Asian macaques, Macaca fascicularis, M. mulatta, M. nemestrina, and M. leonina. M. fascicularis is commonly used as a model for AIDS research, but TRIMCyp has not been analyzed in detail in this species. We analyzed the prevalence of TRIMCyp in samples from Indonesia, Indochina, the Philippines, and Mauritius. We found that TRIMCyp is present at a higher frequency in Indonesian than in Indochinese M. fascicularis macaques and is also present in samples from the Philippines. TRIMCyp is absent in Mauritian M. fascicularis macaques. We then analyzed the restriction specificity of TRIMCyp derived from three animals of Indonesian origin. One allele, like the prototypic TRIMCyp alleles described for M. mulatta and M. nemestrina, restricts human immunodeficiency virus type 2 (HIV-2) and feline immunodeficiency virus (FIV) but not HIV-1. The others restrict HIV-1 and FIV but not HIV-2. Mutagenesis studies confirmed that polymorphisms at amino acid residues 369 and 446 in TRIMCyp (or residues 66 and 143 in the cyclophilin A [CypA] domain) confer restriction specificity. Additionally, we identified a polymorphism in the coiled-coil domain that appears to affect TRIMCyp expression or stability. Taken together, these data show that M. fascicularis has the most diverse array of TRIM5 restriction factors described for any primate species to date. These findings are relevant to our understanding of the evolution of retroviral restriction factors and the use of M. fascicularis models in AIDS research.

The cDNA encoding an antiviral protein SP-2 against BmNPV was cloned from the midgut of Chinese wild silkworm, Bombyx mandarina Moore (GenBank access AY945210) based on the available information of the domesticated silkworm. Its cDNA was 855 bp encoding 284 amino acids with predicted molecular weight of 29.6 kDa. Its full length in genomics was 1376 bp, including 5 exons and 4 introns. The expression analysis indicated that it was only expressed in midgut, and its expression level was higher during feeding stage of larval instars while very lower during the moltism and mature stages. The deduced amino acid sequence of this protein showed eight-amino-acid variation compared with the counterpart of domesticated silkworm. Its antiviral activity was assayed through in vitro test. The results indicated that it showed strong bioactivity against BmNPV, and its activity was 1.6 fold higher that the counterpart of domesticated silkworm.

Severe acute respiratory syndrome coronavirus (SARS-CoV) is the pathogen of SARS, which caused a global panic in 2003. We describe here the screening of Chinese herbal medicine-based, novel small molecules that bind avidly with the surface spike protein of SARS-CoV and thus can interfere with the entry of the virus to its host cells. We achieved this by using a two-step screening method consisting of frontal affinity chromatography-mass spectrometry coupled with a viral infection assay based on a human immunodeficiency virus (HIV)-luc/SARS pseudotyped virus. Two small molecules, tetra-O-galloyl-beta-D-glucose (TGG) and luteolin, were identified, whose anti-SARS-CoV activities were confirmed by using a wild-type SARS-CoV infection system. TGG exhibits prominent anti-SARS-CoV activity with a 50% effective concentration of 4.5 microM and a selective index of 240.0. The two-step screening method described here yielded several small molecules that can be used for developing new classes of anti-SARS-CoV drugs and is potentially useful for the high-throughput screening of drugs inhibiting the entry of HIV, hepatitis C virus, and other insidious viruses into their host cells.