Whole-genome analysis of the recombination and evolution of newly identified NADC30-like porcine reproductive and respiratory syndrome virus strains circulated in Gansu province of China in 2023.

Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the major threats to swine industry, resulting in huge economic losses worldwide. Currently, PRRSV has diversified into multiple lineages with characteristics of extensive recombination in China. In this research, three virus strains were isolated and four virus whole genome sequences were generated and analyzed from clinical samples collected in Gansu province of China in 2023. The four virus strains were designated GSTS4-2023, GSLX2-2023, GSFEI2-2023 and GSBY4-2023. Phylogenetic analysis based on ORF5 sequences showed that GSTS4-2023, GSLX2-2023, GSFEI2-2023 and GSBY4-2023 shared 91.7, 91.2, 93.2 and 92.9% homology with NADC30 strain respectively, and belonged to lineage 1 of PRRSV-2. In addition, one amino acid deletion was observed at position 33 in ORF5 of GSTS4-2023, GSLX2-2023 and GSFEI2-2023. Moreover, amino acid alignment of the four strains showed a typical discontinuous 131-amino acid (aa) deletion in NSP2 for NADC30-like virus strains. Recombination analysis revealed that all four strains originated from NADC30 (lineage 1), with their minor parents coming from JXA1-like strains (lineage 8), VR-2332-like strains (lineage5) and QYYZ-like strains (lineage3). Finally, the three isolated virus strains, GSTS4-2023, GSLX2-2023 and GSFEI2-2023 showed relatively low levels of replication in cell culture. Our findings provide important implications for the field epidemiology of PRRSV.

Caffeic acid phenethyl ester: an effective antiviral agent against porcine reproductive and Respiratory Syndrome Virus.

Porcine Reproductive and Respiratory Syndrome (PRRS) presents a formidable viral challenge in swine husbandry. Confronting the constraints of existing veterinary pharmaceuticals and vaccines, this investigation centers on Caffeic Acid Phenethyl Ester (CAPE) as a prospective clinical suppressant for the Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). The study adopts an integrated methodology to evaluate CAPE's antiviral attributes. This encompasses a dual-phase analysis of CAPE's interaction with PRRSV, both in vitro and in vivo, and an examination of its influence on viral replication. Varied dosages of CAPE were subjected to empirical testing in animal models to quantify its efficacy in combating PRRSV infections. The findings reveal a pronounced antiviral potency, notably in prophylactic scenarios. As a predominant component of propolis, CAPE stands out as a promising candidate for clinical suppression, showing exceptional effectiveness in pre-exposure prophylaxis regimes. This highlights the potential of CAPE in spearheading cutting-edge strategies for the management of future PRRSV outbreaks.

Schlafen-5 inhibits LINE-1 retrotransposition.

Long interspersed element 1 (LINE-1) is the only currently known active autonomous transposon in humans, and its retrotransposition may cause deleterious effects on the structure and function of host cell genomes and result in sporadic genetic diseases. Host cells therefore developed defense strategies to restrict LINE-1 mobilization. In this study, we demonstrated that IFN-inducible Schlafen5 (SLFN5) inhibits LINE-1 retrotransposition. Mechanistic studies revealed that SLFN5 interrupts LINE-1 ribonucleoprotein particle (RNP) formation, thus diminishing nuclear entry of the LINE-1 RNA template and subsequent LINE-1 cDNA production. The ability of SLFN5 to bind to LINE-1 RNA and the involvement of the helicase domain of SLFN5 in its inhibitory activity suggest a mechanism that SLFN5 binds to LINE-1 RNA followed by dissociation of ORF1p through its helicase activity, resulting in impaired RNP formation. These data highlight a new mechanism of host cells to restrict LINE-1 mobilization.

Bacillus subtilis vector based oral rabies vaccines induced potent immune response and protective efficacy in mice.

Introduction: Rabies is a worldwide epidemic that poses a serious threat to global public health. At present, rabies in domestic dogs, cats, and some pets can be effectively prevented and controlled by intramuscular injection of rabies vaccine. But for some inaccessible animals, especially stray dogs, and wild animals, it is difficult to prevent with intramuscular injection. Therefore, it is necessary to develop a safe and effective oral rabies vaccine. Methods: We constructed recombinant Bacillus subtilis (B. subtilis) expressing two different strains of rabies virus G protein, named CotG-E-G and CotG-C-G, immunogenicity was studied in mice. Results: The results showed that CotG-E-G and CotG-C-G could significantly increase the specific SIgA titers in feces, serum IgG titers, and neutralizing antibodies. ELISpot experiments showed that CotG-E-G and CotG-C-G could also induce Th1 and Th2 to mediate the secretion of immune-related IFN-γ and IL-4. Collectively, our results suggested that recombinant B. subtilis CotG-E-G and CotG-C-G have excellent immunogenicity and are expected to be novel oral vaccine candidates for the prevention and control of wild animal rabies.

Exosomal miRNA-328-3p targets ZO-3 and inhibits porcine epidemic diarrhea virus proliferation.

As essential transfer carriers for cell-to-cell communication and genetic material, exosomes carry microRNAs that participate in the regulation of various biological processes. MicroRNAs are a type of single-stranded noncoding RNA that bind to specific target gene mRNAs to degrade or inhibit their translation, thereby regulating target gene expression. Although it is known that a variety of microRNAs are involved in the viral infection process, there are few reports on specific microRNAs involved in porcine epidemic diarrhea virus (PEDV) infection. In this study, we isolated and identified exosomes in PEDV-infected Vero E6 cells. Using transcriptomics technology, we found that miRNA-328-3p was significantly downregulated in exosomes following PEDV infection. Moreover, exosomal miRNA-328-3p inhibited infection by PEDV by targeting and inhibiting tight junction protein 3 (TJP-3/ZO-3) in recipient cells. Our findings provide evidence that, after infecting cells, PEDV downregulates expression of miRNA-328-3p, and the resulting reduced inhibition of the target protein ZO-3 helps to enhance PEDV infection. These results provide new insight for understanding the regulatory mechanism of PEDV infection.

Characteristics of Chimeric West Nile Virus Based on the Japanese Encephalitis Virus SA14-14-2 Backbone.

West Nile virus disease (WND) is an arthropod-borne zoonosis responsible for nonspecific fever or severe encephalitis. The pathogen is West Nile virus belonging to the genus Flavivirus, family Flaviviridae. Every year, thousands of cases were reported, which poses significant public health risk. Here, we constructed a West Nile virus chimera, ChiVax-WN01, by replacing the prMΔE gene of JEV SA14-14-2 with that of the West Nile virus NY99. The ChiVax-WN01 chimera showed clear, different characters compared with that of JEV SA14-14-2 and WNV NY99 strain. An animal study indicated that the ChiVax-WN01 chimera presented moderate safety and immunogenicity for 4-week female BALB/c mice.

Icariin, Formononetin and Caffeic Acid Phenethyl Ester Inhibit Feline Calicivirus Replication In Vitro.

Cats infected with feline calicivirus (FCV) often display oral ulcers and inflammation of the upper respiratory tract, which can lead to death in severe cases. Antiviral therapy is one of the most effective ways to control FCV infection. Natural compounds in Chinese herbal medicines and medicinal plants provide abundant resources for research on antiviral drugs. In this study, we found that icariin (ICA), formononetin (FMN) and caffeic acid phenethyl ester (CPAE) show low cytotoxicity towards F81 cells, that the three natural compounds have apparent antiviral effects on FCV in vitro, and that they can inhibit different FCV strains. Then, we found that ICA and FMN mainly function in the early stage of FCV infection, while CAPE can function in both the early and late stages of FCV infection. Finally, we found that ICA has an antagonistic effect on FMN and CAPE in FCV infection, and FMN has a synergistic effect with CAPE against FCV infection. Our results showed that ICA, FMN and CAPE may be potential drug candidates for FCV-induced diseases.

Antiviral effect of copper chloride on feline calicivirus and synergy with ribavirin in vitro.

BACKGROUND: Feline calicivirus (FCV) is a common and highly prevalent pathogen causing upper respiratory diseases in kittens and felines in recent years. Due to the substantial genetic variability of the viral genes, existing vaccines cannot provide complete protection. Therefore, research on FCV antiviral drugs has received much attention. RESULTS: In this study, we found that copper chloride had dose-dependent antiviral effects on FCV in F81 cells. We also found that the combination of copper chloride and ribavirin had a synergistic protective effect against FCV in F81 cells. In contrast, the combination of copper chloride and horse anti-FCV immunoglobulin F (ab')2 showed an antagonistic effect, likely because copper chloride has an effect on F (ab')2 immunoglobulin; however, further research is needed to clarify this supposition. CONCLUSIONS: In summary, we found that copper chloride had low cytotoxicity and significant antiviral effects on FCV in F81 cells, providing a new drug candidate for the prevention and treatment of FCV infection.

Nitazoxanide protects cats from feline calicivirus infection and acts synergistically with mizoribine in vitro.

Feline calicivirus (FCV) is a highly contagious pathogen that causes acute upper respiratory infections and oral disease in cats, thus seriously endangering feline health. Recently, there have been outbreaks of particularly virulent variant strains of FCV, which can cause both acute symptoms and fatal systemic disease. The discovery of effective antiviral agents to treat FCV infection is, therefore, gradually assuming increased importance. In this study, we showed that both nitazoxanide and mizoribine had antiviral activity in F81 cells infected with different strains of FCV and also demonstrated a synergistic effect between the two drugs. Experiments in cats challenged with FCV showed that nitazoxanide significantly reduced the clinical symptoms of FCV infection, reduced viral load in the trachea and lungs, and reduced viral shedding. Our results showed that nitazoxanide and mizoribine could potentially be used as therapeutic agents to treat FCV infection.

Equine immunoglobulin F(ab')2 fragments protect cats against feline calicivirus infection.

Feline calicivirus (FCV) causes upper respiratory tract infections in felines and threatens the health of wild and domestic felines. Clinically, specific drugs to treat FCV have not yet been developed. Here, IgG was extracted from inactivated FCV-immunized horse sera. Equine F(ab')2 fragments were obtained from pepsin-digested IgG and then purified by protein-G column chromatography. In our study, equine immunoglobulin F(ab')2 fragments showed efficient neutralizing activity in vitro against FCV and had therapeutic and prophylactic effects in FCV-infected cats. The anti-FCV-specific F(ab')2 fragment can significantly alleviate the clinical symptoms of FCV-infected cats and reduce the viral loads of the trachea, lung and spleen. These results indicate that the F(ab')2 fragment prepared from inactivated FCV-immunized horses may be used as a prophylactic and therapeutic agent for diseases caused by FCV.