Antiviral activity of PHA767491 on Caprine alphaherpesvirus 1 in vitro

In Vitro Activity of Ozone/Oxygen Gaseous Mixture against a Caprine Herpesvirus Type 1 Strain Isolated from a Goat with Vaginitis

Alphaherpesviruses cause genital lesions and reproductive failure in both humans and animals. Their control is mainly based on prevention using hygienic prophylactic measures due to the absence of vaccines and limitations of antiviral drug therapy. Ozone is an oxidating gas showing a strong microbicidal activity on bacteria, fungi, viruses, and protozoa. The present study assessed the in vitro virucidal and antiviral activity of ozone against caprine herpesvirus type 1 (CpHV-1). The virucidal activity of a gaseous mixture containing O₃ at 20 and 50 μg/mL was assessed against the virus at different contact times (30 s, 60 s, 90 s, 120 s, 180 s, and 300 s). Antiviral activity of a gaseous mixture containing O₃ at 20 and 50 μg/mL was evaluated against the virus after 30 s and 60 s. Ozone displayed significant virucidal activity when used at all the tested concentrations whilst significant antiviral activity was observed using ozone at 50 μg/mL. The gaseous mixture, tested in the present study, showed virucidal and antiviral activity against CpHV-1 in a dose- and time contact-dependent fashion. Ozone therapy could be evaluated in vivo for the treatment of CpHV-1-induced genital lesions in goats using topical applications.

ERDRP-0519 inhibits feline coronavirus in vitro

Background

Coronaviruses (CoVs) are major human and animal pathogens and antiviral drugs are pursued as a complementary strategy, chiefly if vaccines are not available. Feline infectious peritonitis (FIP) is a fatal systemic disease of felids caused by FIP virus (FIPV), a virulent pathotype of feline enteric coronavirus (FeCoV). Some antiviral drugs active on FIPV have been identified, but they are not available in veterinary medicine. ERDRP-0519 (ERDRP) is a non-nucleoside inhibitor, targeting viral RNA polymerase, effective against morbilliviruses in vitro and in vivo.

Results

The antiviral efficacy of ERDRP against a type II FIPV was evaluated in vitro in Crandell Reese Feline Kidney (CRFK) cells. ERDRP significantly inhibited replication of FIPV in a dose-dependent manner. Viral infectivity was decreased by up to 3.00 logarithms in cell cultures whilst viral load, estimated by quantification of nucleic acids, was reduced by nearly 3.11 logaritms.

Conclusions

These findings confirm that ERDRP is highly effective against a CoV. Experiments will be necessary to assess whether ERDRP is suitable for treatment of FIPV in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03153-3.

Transcriptome and Proteomic Analysis Reveals Up-Regulation of Innate Immunity-Related Genes Expression in Caprine Herpesvirus 1 Infected Madin Darby Bovine Kidney Cells

Caprine herpesvirus 1 (CpHV-1) is a member of the alpha subfamily of herpesviruses, which is responsible for genital lesions and latent infections in goat populations worldwide. In this study, for the first time, the transcriptome and proteomics of CpHV-1 infected Madin Darby bovine kidney (MDBK) cells were explored using RNA-Sequencing (RNA-Seq) and isobaric tags for relative and absolute quantitation-liquid chromatography tandem mass spectrometry (iTRAQ-LC-MS/MS) technology, respectively. RNA-Seq analysis revealed 81 up-regulated and 19 down-regulated differentially expressed genes (DEGs) between infected and mock-infected MDBK cells. Bioinformatics analysis revealed that most of these DEGs were mainly involved in the innate immune response, especially the interferon stimulated genes (ISGs). Gene Ontology (GO) enrichment analysis results indicated that the identified DEGs were significantly mainly enriched for response to virus, defense response to virus, response to biotic stimulus and regulation of innate immune response. Viral carcinogenesis, the RIG-I-like receptor signaling pathway, the cytosolic DNA-sensing pathway and pathways associated with several viral infections were found to be significantly enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database. Eleven selected DEGs (Mx1, RSAD2, IFIT1, IFIT2, IFIT5, IFIH1, IFITM3, IRF7, IRF9, OAS1X and OAS1Y) associated with immune responses were selected, and they exhibited a concordant direction both in RNA-Seq and quantitative real-time RT-PCR analysis. Proteomic analysis also showed significant up-regulation of innate immunity-related proteins. GO analysis showed that the differentially expressed proteins were mostly enriched in defense response and response to virus, and the pathways associated with viral infection were enriched under KEGG analysis. Protein-protein interaction network analysis indicated most of the DEGs related to innate immune responses, as DDX58(RIG-I), IFIH1(MDA5), IRF7, Mx1, RSAD2, OAS1 and IFIT1, were located in the core of the network and highly connected with other DGEs. Our findings support the notion that CpHV-1 infection induced the transcription and protein expression alterations of a series of genes related to host innate immune response, which helps to elucidate the resistance of host cells to viral infection and to clarify the pathogenesis of CpHV-1.

Virucidal and antiviral effects of Thymus vulgaris essential oil on feline coronavirus

Feline infectious peritonitis (FIP) is a fatal systemic disease of felids caused by a Coronavirus (CoV) (FIPV). In spite of its clinical relevance and impact on feline health, currently the therapeutic possibilities for treatment of FIP in cats are limited. The emergence of the pandemic Severe Respiratory Syndrome (SARS) coronavirus (CoV) type 2 (SARS-CoV-2), etiological agent of the 2019 Coronavirus Disease (COVID-19), able to infect a broad spectrum of animal species including cats, triggered the interest for the development of novel molecules with antiviral activity for treatment of CoV infections in humans and animals.

Essential oils (EOs) have raised significant attention for their antiviral properties integrating and, in some cases, replacing conventional drugs. Thymus vulgaris EO (TEO) has been previously shown to be effective against several RNA viruses including CoVs. In the present study the antiviral efficacy of TEO against FIPV was evaluated in vitro.

TEO at 27 μg/ml was able to inhibit virus replication with a significant reduction of 2 log10 TCID₅₀/50 μl. Moreover, virucidal activity was tested using TEO at 27 and 270 μg/ml, over the cytotoxic threshold, determining a reduction of viral titre as high as 3.25 log10 TCID₅₀/50 μl up to 1 h of time contact. These results open several perspectives in terms of future applications and therapeutic possibilities for coronaviruses considering that FIPV infection in cats could be a potential model for the study of antivirals against CoVs.

Establishment of caprine airway epithelial cells grown in an air-liquid interface system to study caprine respiratory viruses and bacteria

Respiratory diseases negatively impact the global goat industry, but are understudied. There is a shortage of established and biological relevant in vitro or ex vivo assays to study caprine respiratory infections. Here, we describe the establishment of an in vitro system based on well-differentiated caprine airway epithelial cell (AEC) cultures grown under air liquid interface conditions as an experimental platform to study caprine respiratory pathogens. The functional differentiation of the AEC cultures was monitored and confirmed by light and immunofluorescence microscopy, scanning electron microscopy and examination of histological sections. We validated the functionality of the platform by studying Influenza D Virus (IDV) infection and Mycoplasma mycoides subsp. capri (Mmc) colonization over 5 days, including monitoring of infectious agents by titration and qPCR as well as colour changing units, respectively. The inoculation of caprine AEC cultures with IDV showed that efficient viral replication takes place, and revealed that IDV has a marked cell tropism for ciliated cells. Furthermore, AEC cultures were successfully infected with Mmc using a multiplicity of infection of 0.1 and colonization was monitored over several days. Altogether, these results demonstrate that our newly-established caprine AEC cultures can be used to investigate host-pathogen interactions of caprine respiratory pathogens.

Antiviral activity of Α-hydroxytropolones on caprine alphaherpesvirus 1 in vitro

The emergence of human alphaherpesvirus strains (i.e. HHV-1 and -2) resistant to commonly used antiviral drugs has prompted the research for alternative, biologically active anti-herpetic agents. Natural-product and synthetic α-hydroxytropolones (αHTs) have been identified as lead therapeutic agents for a number of infections, including HHV-1 and -2, and several veterinary herpesviruses, i.e. bovine alphaherpesvirus 1 (BoHV-1), equine alphaherpesvirus 1 (EHV-1) and feline alphaherpesvirus 1 (FHV-1). In the present study we evaluated the activity in vitro of two natural and two synthetic α-hydroxytropolones (αHTs) against Caprine alphaherpesvirus 1 (CpHV-1) which is regarded as a useful homologous animal model for the study of HSV-2 infection, chiefly for the assessment of antiviral drugs in in vivo studies. AlphaHTs were able to decrease significantly CpHV-1 viral titres up to 4.25 log10 TCID₅₀/50 μl and suppressed extensively CpHV-1 nucleic acids up to 8.71 log10 viral DNA copy number/10 μl. This study demonstrated the efficacy of αHTs against CpHV-1 in vitro, adding to their activity observed against the human and animal alphaherpesviruses in vitro. The activity of αHTs against CpHV-1 appeared similar but not identical to the patterns of activity observed against other alphaherpesviruses, suggesting virus-related variability in terms of response to specific αHT molecules. These findings open several perspectives in terms of future studies using the CpHV-1 homologous animal model, for the development of therapeutic tools against herpesviruses.