Orf virus ORF120 protein positively regulates the NF-κB pathway by interacting with G3BP1

Genistein is effective in inhibiting Orf virus infection in vitro by targeting viral RNA polymerase subunit RPO30 protein

Orf virus (ORFV), a typical member of the genus Parapoxvirus, Poxvirus family, causes a contagious pustular dermatitis in sheep, goats, and humans. Poxviruses encode a multisubunit DNA-dependent RNA polymerase (vRNAP) that carries out viral gene expression in the host cytoplasm, which is a viral factor essential to poxvirus replication. Due to its vital role in viral life, vRNAP has emerged as one of the potential drug targets. In the present study, we investigated the antiviral effect of genistein against ORFV infection. We provided evidence that genistein exerted antiviral effect through blocking viral genome DNA transcription/replication and viral protein synthesis and reducing viral progeny, which were dosedependently decreased in genistein-treated cells. Furthermore, we identified that genistein interacted with the vRNAP RPO30 protein by CETSA, molecular modeling and Fluorescence quenching, a novel antiviral target for ORFV. By blocking vRNAP RPO30 protein using antibody against RPO30, we confirmed that the inhibitory effect exerted by genistein against ORFV infection is mediated through the interaction with RPO30. In conclusion, we demonstrate that genistein effectively inhibits ORFV transcription in host cells by targeting vRNAP RPO30, which might be a promising drug candidate against poxvirus infection.

Role(s) of G3BPs in Human Pathogenesis

Ras-GTPase-activating protein (SH3 domain)-binding proteins (G3BP) are RNA binding proteins that play a critical role in stress granule (SG) formation. SGs protect critical mRNAs from various environmental stress conditions by regulating mRNA stability and translation to maintain regulated gene expression. Recent evidence suggests that G3BPs can also regulate mRNA expression through interactions with RNA outside of SGs. G3BPs have been associated with a number of disease states, including cancer progression, invasion, metastasis, and viral infections, and may be useful as a cancer therapeutic target. This review summarizes the biology of G3BP including their structure, function, localization, role in cancer progression, virus replication, mRNA stability, and SG formation. We will also discuss the potential of G3BPs as a therapeutic target. SIGNIFICANCE STATEMENT: This review will discuss the molecular mechanism(s) and functional role(s) of Ras-GTPase-activating protein (SH3 domain)-binding proteins in the context of stress granule formation, interaction with viruses, stability of RNA, and tumorigenesis.

The orf virus 129 protein can inhibit immune responses by interacting with host complement C1q binding protein in goat turbinate bone cells

OBJECTIVE

Contagious ecthyma is a severe and highly contagious disease caused by an orf virus (ORFV). The virus is responsible for substantial economic losses in the goat industry and threatens humans. We previously determined the role of ORFV129 protein, one of the five ankyrin-repeat proteins coded by the orf genome, in suppressing the transcription of pro-inflammatory cytokines IL-6, IL-1β and IFN-γ. In the present study, we identified 14 cellular proteins (complement C1q binding protein [C1QBP], MCM7, EIF5A, PKM, SLC6A, TSPAN6, ATP6AP2, GPS1, MMADHC, HSPB6, SLC35B1, MTF1, P3H4, and IL15RA) that interact with ORFV129 using a yeast two-hybrid system in goat turbinate bone cells (GFTCs). The interaction between ORFV129 and (C1QBP), an immune-related protein, was confirmed using immunofluorescence co-localization and co-immunoprecipitation assays. C1QBP overexpression inhibited ORFV replication, whereas the knockdown of C1QBP promoted ORFV replication in GFTCs. Furthermore, ORFV or ORFV129 increased C1QBP expression in GFTCs, indicated that ORFV129-C1QBP interaction might contribute to the ORFV-induced host immune process. In addition, our research showed that ORFV increased the expression of ORFV129, cytokine IL-6, IL-1β and IFN-γ. C1QBP overexpression induced IFN-γ production and reduced IL-6 and IL-1β production. Conversely, C1QBP knockdown induced IL-1β production and reduced IFN-γ and IL-1β production. Moreover, augmentation of ORFV129 expression enhanced the inhibition of the secretion of cytokines IL-6, IL-1β, and IFN-γ induced by the altered expression of C1QBP. These findings suggest different downstream pathways might be involved in regulating different cytokines induced by ORFV129 expression in GFTCs.

KIF14 promotes proliferation, lymphatic metastasis and chemoresistance through G3BP1/YBX1 mediated NF-κB pathway in cholangiocarcinoma

Cholangiocarcinoma (CCA), a highly lethal and fetal cancer derived from the hepatobiliary system, is featured by aggressive growth and early lymphatic metastasis. Elucidating the underlying mechanism and identifying the effective therapy are critical for advanced CCA patients. In the study, we detected that KIF14 was upregulated in CCA samples, especially in patients with lymph node metastasis and vascular invasion. CCA patients with higher KIF14 were associated with worse overall survival and recurrence-free survival after surgery. Gain-of and loss-of function studies showed that KIF14 enhanced CCA cells proliferation, migration, invasion and lymphatic metastasis whereas its silencing abolished the effects in vivo and in vitro. Mechanistic investigation showed that KIF14 bound to the G3BP1/YBX1 complex and facilitated their interaction, causing increased activity of the NF-κB promoter and activation of NF-κB pathway. Furthermore, increased KIF14 level enhanced chemotherapy-resistance to gemcitabine-based regimen and induced immunosuppressive microenvironment. In addition, KIF14 was direct target of HNF4A and inversely regulated by HNF4A. Together, these findings suggested that KIF14 could be a potential oncogene and a good indicator in predicting prognosis and chemotherapy guidance for CCA patients.

Recent advances in diagnostic approaches for orf virus

Orf virus (ORFV), the prototype species of the Parapoxvirus genus, is an important zoonotic virus, causing great economic losses in livestock production. At present, there are no effective drugs for orf treatment. Therefore, it is crucial to develop accurate and rapid diagnostic approaches for ORFV. Over decades, various diagnostic methods have been established, including conventional methods such as virus isolation and electron microscopy; serological methods such as virus neutralization test (VNT), immunohistochemistry (IHC) assay, immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA); and molecular methods such as polymerase chain reaction (PCR), real-time PCR, loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and recombinase-aided amplification (RAA) assay. This review provides an overview of currently available diagnostic approaches for ORFV and discusses their advantages and limitations and future perspectives, which would be significantly helpful for ORFV early diagnosis and surveillance to prevent outbreak of orf. KEY POINTS: • Orf virus emerged and reemerged in past years • Rapid and efficient diagnostic approaches are needed and critical for ORFV detection • Novel and sensitive diagnostic methods are required for ORFV detection.

Oncolytic Parapoxvirus induces Gasdermin E-mediated pyroptosis and activates antitumor immunity

The advantage of oncolytic viruses (OV) in cancer therapy is their dual effect of directly killing tumours while prompting anti-tumour immune response. Oncolytic parapoxvirus ovis (ORFV) and other OVs are thought to induce apoptosis, but apoptosis, being the immunogenically inert compared to other types of cell death, does not explain the highly inflamed microenvironment in OV-challenged tumors. Here we show that ORFV and its recombinant therapeutic derivatives are able to trigger tumor cell pyroptosis via Gasdermin E (GSDME). This effect is especially prominent in GSDME-low tumor cells, in which ORFV-challenge pre-stabilizes GSDME by decreasing its ubiquitination and subsequently initiates pyroptosis. Consistently, GSDME depletion reduces the proportion of intratumoral cytotoxic T lymphocytes, pyroptotic cell death and the success of tumor ORFV virotherapy. In vivo, the OV preferentially accumulates in the tumour upon systemic delivery and elicits pyroptotic tumor killing. Consequentially, ORFV sensitizes immunologically 'cold' tumors to checkpoint blockade. This study thus highlights the critical role of GSDME-mediated pyroptosis in oncolytic ORFV-based antitumor immunity and identifies combinatorial cancer therapy strategies.

Establishment of a sheep immortalization cell line for generating and amplifying Orf virus recombinants

Orf virus (ORFV) causes highly contagious vesiculoulcerative pustular and skin lesions in ruminants like sheep. Developing ORFV-based recombinant vaccine is a potential way to combat Orf disease. Although ORFV could propagate in some kinds of primary cells, the proliferative capacity of primary cells is limited. Therefore, establishing immortalized stable cell line is an effective and affordable way for the production of live ORFV vaccine. In the present study, we introduced a telomerase reverse transcriptase (TERT) gene-expressing cassette into primary ovine fetal turbinate (OFTu) cells, then selected and expanded the cells, which was considered as immortalized OFTu cell line. Our results showed that TERT introduction has successfully expended the lifespan of OFTu cell line over 80 passages, without changing the cellular morphology, affecting chromosomes karyotype and inducing the cellular tumorigenic ability. Immortalized OFTu cell line-derived ORFV has caused similar levels of cytopathic effects (CPE), viral titers and viral particles when compared with the ORFV from primary OFTu cell. Importantly, immortalized OFTu cell line was suitable for generating gene-modified ORFV recombinant through homologous recombination, and for the amplification of ORFV recombinant. In summary, an immortalized OFTu cell line was established and characterized, which could be a powerful tool for preparing ORFV recombinant vaccines.

Construction and characterization of a contagious ecthyma virus double-gene deletion strain and evaluation of its potential as a live-attenuated vaccine in goat

Contagious ecthyma is a highly contagious viral disease with zoonotic significance caused by orf virus (ORFV) that affects domestic, ruminants and humans. Live attenuated virus and attenuated tissue culture vaccines are widely used in the fight against ORFV, however, the conventional attenuated vaccine strains have many drawbacks. The aim of this project was to construct a promising contagious ecthyma vaccine strain with safety, high protection efficacy and accessibility by genetic manipulation to against the disease. Using a natural ORFV-GS14 strain as the parental virus, recombinant virus, rGS14-ΔCBP-ΔGIF, with double deletions in the genes encoding the chemokine binding protein (CBP) and granulocyte/macrophage colony-stimulating factor inhibitory factor (GIF) was generated and characterized in vitro and in vivo. Results showed that the growth kinetics curve of rGS14-ΔCBP-ΔGIF and parental virus was consistent, both reaching plateau phase at 48 h post infection, which indicated that the double deletion of cbp and gif genes had little impact on the replication properties of the recombinant virus in primary goat testis (PGT) cell cultures compared with the parental virus. The safety of the double gene-deleted virus was evaluated in lambs. The lambs were monitored for 21 days post infection of the recombinant virus and no ORFV associated symptoms were observed in 21 days post-infection except for slight fever and anorexia in 5 days post-infection, and all lambs inoculated with either recombinant virus or PBS exhibited no clinical signs. To assess the protection efficacy of the rGS14-ΔCBP-ΔGIF, groups of four lambs each were inoculated with rGS14-ΔCBP-ΔGIF, rGS14-ΔCBP, rGS14-ΔGIF or PBS and challenged by a wild type virulent ORFV strain that was isolated from proliferative scabby lesions tissues of infected goat at 21-day post-inoculation. During 14 days post-challenging, lambs inoculated with rGS14-ΔCBP-ΔGIF all remained healthy with unimmunized group all infected, while the single gene-deleted viruses only protected 40% to 50% animals. These results indicated that the double gene-deleted recombinant virus could provide complete protection against virulent ORFV challenging. In conclusion, the double gene-deleted recombinant virus strain, rGS14-ΔCBP-ΔGIF, would be a promising candidate vaccine strains with safety, high protection efficacy and availability.

Maladaptation after a virus host switch leads to increased activation of the pro-inflammatory NF-κB pathway

Myxoma virus (MYXV) is benign in the natural brush rabbit host but causes a fatal disease in European rabbits. Here, we demonstrate that MYXV M156 inhibited brush rabbit protein kinase R (bPKR) more efficiently than European rabbit PKR (ePKR). Because ePKR was not completely inhibited by M156, there was a depletion of short–half-life proteins like the nuclear factor kappa B (NF-κB) inhibitor IκBα, concomitant NF-κB activation and NF-κB target protein expression in ePKR-expressing cells. NF-κB pathway activation was blocked by either hypoactive or hyperactive M156 mutants. This demonstrates that maladaptation of viral immune antagonists can result in substantially different immune responses in aberrant hosts. These different host responses may contribute to altered viral dissemination and may influence viral pathogenesis.

Myxoma virus (MYXV) causes localized cutaneous fibromas in its natural hosts, tapeti and brush rabbits; however, in the European rabbit, MYXV causes the lethal disease myxomatosis. Currently, the molecular mechanisms underlying this increased virulence after cross-species transmission are poorly understood. In this study, we investigated the interaction between MYXV M156 and the host protein kinase R (PKR) to determine their crosstalk with the proinflammatory nuclear factor kappa B (NF-κB) pathway. Our results demonstrated that MYXV M156 inhibits brush rabbit PKR (bPKR) more strongly than European rabbit PKR (ePKR). This moderate ePKR inhibition could be improved by hyperactive M156 mutants. We hypothesized that the moderate inhibition of ePKR by M156 might incompletely suppress the signal transduction pathways modulated by PKR, such as the NF-κB pathway. Therefore, we analyzed NF-κB pathway activation with a luciferase-based promoter assay. The moderate inhibition of ePKR resulted in significantly higher NF-κB–dependent reporter activity than complete inhibition of bPKR. We also found a stronger induction of the NF-κB target genes TNFα and IL-6 in ePKR-expressing cells than in bPKR-expressing cells in response to M156 in both transfection and infections assays. Furthermore, a hyperactive M156 mutant did not cause ePKR-dependent NF-κB activation. These observations indicate that M156 is maladapted for ePKR inhibition, only incompletely blocking translation in these hosts, resulting in preferential depletion of short–half-life proteins, such as the NF-κB inhibitor IκBα. We speculate that this functional activation of NF-κB induced by the intermediate inhibition of ePKR by M156 may contribute to the increased virulence of MYXV in European rabbits.

The roles of G3BP1 in human diseases (review)

Ras-GTPase-activating protein binding protein 1 (G3BP1) is a multifunctional binding protein involved in a variety of biological functions, including cell proliferation, metastasis, apoptosis, differentiation and RNA metabolism. It has been revealed that G3BP1, as an antiviral factor, can interact with viral proteins and regulate the assembly of stress granules (SGs), which can inhibit viral replication. Furthermore, several viruses have the ability to hijack G3BP1 as a cofactor, recruiting translation initiation factors to promote viral proliferation. However, many functions of G3BP1 are associated with other diseases. In various cancers, G3BP1 is a cancer-promoting factor, which can promote the proliferation, invasion and metastasis of cancer cells. Moreover, compared with normal tissues, G3BP1 expression is higher in tumor tissues, indicating that it can be used as an indicator for cancer diagnosis. In this review, the structure of G3BP1 and the regulation of G3BP1 in multiple dimensions are described. In addition, the effects and potential mechanisms of G3BP1 on various carcinomas, viral infections, nervous system diseases and cardiovascular diseases are elucidated, which may provide a direction for clinical applications of G3BP1 in the future.

Metagenomics of the midgut microbiome of Rhipicephalus microplus from China

Background

Ticks, which are ectoparasites of animals, may carry multiple pathogens. The cattle tick Rhipicephalus microplus is an important bovine parasite in China. However, the midgut microbiome of R. microplus from China has not been characterized via metagenomic methods.

Methods

Rhipicephalus microplus were collected from cattle in the city of Changsha in Hunan province, China. The DNA of the midgut contents was extracted from fully engorged adult female R. microplus. A DNA library was constructed and sequenced using an Illumina HiSeq sequencing platform. SOAPdenovo software was used to assemble and analyze the clean data. The latent class analysis algorithm applied to system classification by MEGAN software was used to annotate the information on the species’ sequences. DIAMOND software was used to compare unigenes with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and functional annotation was carried out based on the results of the comparison.

Results

The dominant phyla in the five samples were Firmicutes, Proteobacteria, and Actinobacteria. Streptococcus, Mycobacterium, Anaplasma, Enterococcus, Shigella, Lactobacillus, Brachyspira, Pseudomonas, Enterobacter, Bacillus, and Lactococcus were the dominant genera in the five samples. The endosymbiotic bacterium Wolbachia was also detected in all of the samples. Mycobacterium malmesburyense, Streptococcus pneumoniae, Anaplasma phagocytophilum, Enterococcus faecium, Shigella sonnei, Enterococcus faecalis, Lactobacillus casei, Brachyspira hampsonii, Pseudomonas syringae, Enterobacter cloacae, and Lactococcus garvieae were the dominant species in the five samples. In addition to these bacterial species, we also detected some eukaryotes, such as Rhizophagus irregularis, Enterospora canceri, Smittium culicis, Zancudomyces culisetae, Trachipleistophora hominis, and viruses such as orf virus, human endogenous retrovirus type W, enzootic nasal tumor virus of goats, bovine retrovirus CH15, and galidia endogenous retrovirus in all of the samples at the species level. The results of the annotated KEGG pathway predictions for the gene functions of the midgut microflora of R. microplus indicated genes involved in lipid and amino acid metabolism, infectious diseases (e.g., Streptococcuspneumonia infection, human granulocytic anaplasmosis, Shigellasonnei infection, Salmonella enterica infection, and pathogenic Escherichia coli infection), and cancer.

Conclusions

Our study revealed that the midgut microbiome of R. microplus is not only composed of a large number of bacteria, but that a portion also comprises eukaryotes and viruses. The data presented here enhance our understanding of this tick’s midgut microbiome and provide fundamental information for the control of ticks and tick-borne diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05161-6.

Research Progress on the Structure and Function of G3BP

Ras-GTPase-activating protein (SH3 domain)-binding protein (G3BP) is an RNA binding protein. G3BP is a key component of stress granules (SGs) and can interact with many host proteins to regulate the expression of SGs. As an antiviral factor, G3BP can interact with viral proteins to regulate the assembly of SGs and thus exert antiviral effects. However, many viruses can also use G3BP as a proximal factor and recruit translation initiation factors to promote viral proliferation. G3BP regulates mRNA translation and attenuation to regulate gene expression; therefore, it is closely related to diseases, such as cancer, embryonic death, arteriosclerosis, and neurodevelopmental disorders. This review discusses the important discoveries and developments related G3BP in the biological field over the past 20 years, which includes the formation of SGs, interaction with viruses, stability of RNA, and disease progression.