Molecular characteristics and pathogenicity of an equid alphaherpesvirus 1 strain isolated in China.

Equid alphaherpesvirus 1 (EHV-1) is prevalent in China, and causes notable economic damage to the equine industry. However, there is no information regarding the molecular characteristics and pathogenicity of the Chinese strains. Therefore, an EHV-1 strain, named YM2019, was isolated from the lung tissue of an aborted horse fetus in Xinjiang, China, and its genome and pathogenicity were analyzed. The full genome of the isolate was 150,267 base pairs in length, with 56.7% G + C content. Genetic and phylogenetic analysis showed that strain YM2019 (GenBank: MT063054) belonged to the ORF30 N752 genotype but displayed a high level of similarity with strain Ab4 (ORF30 D752, GenBank: AY665713) isolated in Britain. Fourteen unique amino acid mutations were found when comparing strain YM2019 with the reference strains Ab4 and V592 (ORF30 N752, GenBank: AY464052). Syrian hamsters infected with strain YM2019 exhibited severe respiratory and neurological clinical signs and died. Infection with strain YM2019 in Yili horses caused rhinopneumonitis, viremia, and neurological clinical signs such as hind limb lameness, prostration, and reduced movement. Here, we describe the features of an EHV-1 strain discovered in China, together with the complete genome sequence, and reveal that a nonneurovirulent strain (ORF30 N752) can also cause neurological signs in horses. The data will be useful in providing some reference for further research into the relationship between viral genotypes and pathogenicity.

TLR-5 agonist Salmonella abortus equi flagellin FliC enhances FliC-gD-based DNA vaccination against equine herpesvirus 1 infection.

Equine herpesvirus 1 (EHV-1) induces serious respiratory infections, viral abortion, neurological signs, and neonatal mortality in horses. Despite the use of vaccines, EHV-1 infection also causes a high annual economic burden to the equine industry. The poor immunogenicity of and protection conferred by EHV-1 vaccines are the major factors responsible for the spread of EHV-1 infection. The present study examined the immunogenicity of a novel DNA vaccine co-expressing FliC, a flagellin protein, in Salmonella abortus equi and the gD protein of EHV-1. Mice and horses were immunized intramuscularly with the vaccine, and mice were challenged with EHV-1. Immunofluorescence and western blotting revealed that FliC and gD can be efficiently expressed in cells. This novel vaccine significantly increased gD-specific antibody and interferon gamma (IFN-γ) levels in immunized mice and horses. Compared with controls, the viral load and morbidity were markedly reduced in FliC-gD-immunized mice after they were challenged with EHV-1. Furthermore, the immunogenicity of FliC-gD in a natural host was tested. Our results indicate that vaccinated mice and horses exhibit increased humoral and improved cellular immune responses.

[Impact of fluorescent protein tag on gD envelope protein subcellular localization in BHK-21 cells].

Objective: The fluorescent protein and gD envelope protein of equine herpes virus type 1 (EHV-1) were used to study the impact of tags on gD protein subcellular localization in BHK-21 cells. Methods: With the EHV-1 genome as a template, the gD complete gene was amplified by PCR technique. The product of PCR was cloned to pAcGFP1-C1 and pDsRed2-N1 plasmids. The recombinant plasmids were designated as pAc-GFP-gD (GFP-gD) and pDs-gD-Red (gD-Red). The GFP gene was inserted into the posterior position of gD gene signal peptide sequence. The modified gD gene signal peptide sequence was cloned to pVAX-1 plasmid, so that pVAX-S-GFP-gD' (S-GFPgD') recombinant plasmid was constructed. Meanwhile, the flag tag was added to N-terminal of gD sequence and they were cloned to pVAX-1 expression vector for constructing pVAX-Flag-gD recombinant plasmid. The BHK-21 cells were transfected with the 4 different recombinant plasmids and the subcellular localizations of fusion proteins were determined by lasar confocal scan microscopy. Results: Four eukaryotic expression vectors were constructed successfully. In BHK-21 cells, the vast majority of gD envelope proteins was localized in Golgi, and a small amount of gD was localized in the nucleus. Conclusion: Our finding reveals that the fluorescent protein of different insertion sites has no significant effects on the subcellular localization of gD, and provides a useful reference for other researchers.

Transcriptomic Analysis of Metformin's Effect on Bovine Viral Diarrhea Virus Infection.

(1) Background: Bovine viral diarrhea virus (BVDV) causes calf diarrhea, bovine respiratory syndrome, and cow abortion, resulting in substantial economic losses in the cattle industry. Owing to its persistent infection mechanism, BVDV is a major challenge in the treatment of cattle. (2) Methods: To determine how metformin (Met) inhibits the interaction between BVDV and host cells, we treated BVDV-infected cells with Met. We then performed an RNA sequencing (RNA-seq) analysis of Met-treated cells infected with BVDV to identify differentially expressed genes (DEGs). Consequently, the RNA-seq results were validated through real-time quantitative PCR (qPCR). (3) Results: Our analysis revealed 3169 DEGs in the Met-treated cells (Met group) vs. the negative controls (NC group) and 2510 DEGs in the BVDV-infected cells after pretreatment with Met (MetBVDV group) vs. the BVDV-infected cells (BVDV group). The DEGs were involved in MDBK interactions during BVDV infection, as indicated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The potential interactions of the DEGs were confirmed via a protein-protein interaction (PPI) network. Met treatment induced autophagy signaling activity and the expression of the autophagy-related genes ATG2A, ATG4B, ATG10, and ATG12 in BVDV-infected Met-pretreated cells. (4) Conclusions: We found that the host transcriptomic profile was affected by BVDV infection and Met pretreatment. These findings offer valuable new insights and provide support for future studies on the inhibition of BVDV replication by Met.

Breaking Latent Infection: How ORF37/38-Deletion Mutants Offer New Hope against EHV-1 Neuropathogenicity.

Equid alphaherpesvirus 1 (EHV-1) has been linked to the emergence of neurological disorders, with the horse racing industry experiencing significant impacts from outbreaks of equine herpesvirus myeloencephalopathy (EHM). Building robust immune memory before pathogen exposure enables rapid recognition and elimination, preventing infection. This is crucial for effectively managing EHV-1. Removing neuropathogenic factors and immune evasion genes to develop live attenuated vaccines appears to be a successful strategy for EHV-1 vaccines. We created mutant viruses without ORF38 and ORF37/38 and validated their neuropathogenicity and immunogenicity in hamsters. The ∆ORF38 strain caused brain tissue damage at high doses, whereas the ∆ORF37/38 strain did not. Dexamethasone was used to confirm latent herpesvirus infection and reactivation. Dexamethasone injection increased viral DNA load in the brains of hamsters infected with the parental and ∆ORF38 strains, but not in those infected with the ∆ORF37/38 strain. Immunizing hamsters intranasally with the ∆ORF37/38 strain as a live vaccine produced a stronger immune response compared to the ∆ORF38 strain at the same dose. The hamsters demonstrated effective protection against a lethal challenge with the parental strain. This suggests that the deletion of ORF37/38 may effectively inhibit latent viral infection, reduce the neuropathogenicity of EHV-1, and induce a protective immune response.

Development of a live attenuated vaccine candidate for equid alphaherpesvirus 1 control: a step towards efficient protection.

Equid alphaherpesvirus 1 (EqAHV1) is a viral pathogen known to cause respiratory disease, neurologic syndromes, and abortion storms in horses. Currently, there are no vaccines that provide complete protection against EqAHV1. Marker vaccines and the differentiation of infected and vaccinated animals (DIVA) strategy are effective for preventing and controlling outbreaks but have not been used for the prevention of EqAHV1 infection. Glycoprotein 2 (gp2), located on the envelope of viruses (EqAHV1), exhibits high antigenicity and functions as a molecular marker for DIVA. In this study, a series of EqAHV1 mutants with deletion of gp2 along with other virulence genes (TK, UL24/TK, gI/gE) were engineered. The mutant viruses were studied in vitro and then in an in vivo experiment using Golden Syrian hamsters to assess the extent of viral attenuation and the immune response elicited by the mutant viruses in comparison to the wild-type (WT) virus. Compared with the WT strain, the YM2019 Δgp2, ΔTK/gp2, and ΔUL24/TK/gp2 strains exhibited reduced growth in RK-13 cells, while the ΔgI/gE/gp2 strain exhibited significantly impaired proliferation. The YM2019 Δgp2 strain induced clinical signs and mortality in hamsters. In contrast, the YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 variants displayed diminished pathogenicity, causing no observable clinical signs or fatalities. Immunization with nasal vaccines containing YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 elicited a robust immune response in hamsters. In particular, compared with the vaccine containing the ΔTK/gp2 strain, the vaccine containing the ΔUL24/TK/gp2 strain demonstrated enhanced immune protection upon challenge with the WT virus. Furthermore, an ELISA for gp2 was established and refined to accurately differentiate between infected and vaccinated animals. These results confirm that the ΔUL24/TK/gp2 strain is a safe and effective live attenuated vaccine candidate for controlling EqAHV1 infection.

Berbamine, a bioactive alkaloid, suppresses equine herpesvirus type 1 in vitro and in vivo.

Equine herpesvirus type 1 (EHV-1) poses a global threat to equines. The anticancer agent berbamine (BBM), a bioactive alkaloid, has been shown to inhibit viral infection. However, whether BBM can inhibit EHV-1 infection remains unclear. This study investigated the effect of BBM treatment on EHV-1 infection. Quantitative PCR (qPCR), immunoblotting, the Reed-Muench method, and pathological examination were employed to study the ability of BBM to inhibit EHV-1 infection, viral DNA replication, viral protein production, virion secretion, and cytopathogenesis in vitro and in vivo. The in vitro studies revealed that 10 µM BBM effectively suppressed EHV-1 viral entry into cells, viral DNA replication, and virion secretion, while the in vivo studies verified the ability of BBM to suppress EHV-1-induced damage of brain and lung tissues and animal mortality. These findings strongly suggest that BBM could be a serious contender in the therapeutic control of EHV-1 infection of equines.

Co-existence of multiple strains of porcine circovirus type 2 in the same pig from China.

Pigs are often co-infected by different viral strains from the same virus. Up to now, there are few reports about co-existence of different porcine circovirus type 2 (PCV2) strains in China. The aim of this study was to evaluate it in Chinese swine herds. 118 PCV2 positive DNAs isolated from diseased pigs identified by classic PCR were re-detected using a modified differential PCR assay. The results indicated that co-existence rates of PCV2 were 32.2% (38/118) in diseased pigs and 0% (0/41) in asymptomatic pigs. Four PCV2 complete genomes were cloned from two co-infected samples and their nucleotide (nt) identities were 95%-97.3%. The phylogenetic analysis showed that four PCV2 strains were divided into different genotypes, PCV2a, PCV2b, PCV2d and PCV2e, respectively. In addition, co-existence were not detected in 41 serum samples from healthy pigs but PCV2 single infection (31.7%, 13/41) existed. These data revealed that the co-existence of different strains of PCV2 might contribute to the development of more severe clinical symptoms for pigs. This is the first report confirming the co-existence of different PCV2 strains in Chinese swine herds. Meanwhile, this study could help us to understand new infection and prevalence forms of PCV2 clinically.

High prevalence of a novel porcine bocavirus in weanling piglets with respiratory tract symptoms in China.

This study presents the first evidence of infection by a novel porcine bocavirus (PBoV) in Chinese swine herds. The PCR detection results showed that PBoV was significantly more prevalent in weanling piglets (69.7%, 69/99) with respiratory tract symptoms than that in other samples (0-13.6%) (P < 0.01). Sequence analysis showed that the partial VP1/2 genes were highly conserved (99-100% identity), and only five frequent nucleotide mutation positions existed in Chinese PBoV strains. These data indicate that PBoV might be an emerging virus for swine respiratory tract diseases. This study could help us to better understand the epidemiology of PBoV.

RNA-Seq-based transcriptomic profiling of primary interstitial cells of Cajal in response to bovine viral diarrhea virus infection.

Infections with bovine viral diarrhea virus (BVDV) contribute significantly to health-related economic losses in the beef and dairy industries and are widespread throughout the world. Severe acute BVDV infection is characterized by a gastrointestinal (GI) inflammatory response. The mechanism of inflammatory lesions caused by BVDV remains unknown. The interstitial cells of Cajal (ICC) network plays a pivotal role as a pacemaker in the generation of electrical slow waves for GI motility, and it is crucial for the reception of regulatory inputs from the enteric nervous system. The present study investigated whether ICC were a good model for studying GI inflammatory lesions caused by BVDV infection. Primary ICC were isolated from the duodenum of Merino sheep. The presence of BVDV was detected in ICC grown for five passages after BVDV infection, indicating that BVDV successfully replicated in ICC. After infection with BVDV strain TC, the cell proliferation proceeded slowly or declined. Morphological changes, including swelling, dissolution, and formation of vacuoles in the ICC were observed, indicating quantitative, morphological and functional changes in the cells. RNA sequencing (RNA-Seq) was performed to investigate differentially expressed genes (DEGs) in BVDV-infected ICC and explore the molecular mechanism of underlying quantitative, morphological and functional changes of ICC. Eight hundred six genes were differentially expressed after BVDV infection, of which 538 genes were upregulated and 268 genes were downregulated. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the 806 DEGs were significantly enriched in 27 pathways, including cytokine-cytokine receptor interaction, interleukin (IL)-17 signaling and mitogen-activated protein kinase (MAPK) signaling pathways. The DEGs and raw files of high-throughput sequencing of this study were submitted to the NCBI Gene Expression Omnibus (GEO) database (accession number GSE122344). Finally, 21 DEGs were randomly selected, and the relative repression levels of these genes were tested using the quantitative real-time PCR (qRT-PCR) to validate the RNA-Seq results. The results showed that the related expression levels of 21 DEGs were similar to RNA-Seq. This study is the first to establish a new infection model for investigating GI inflammatory lesions induced by BVDV infection. RNA-Seq-based transcriptomic profiling can provide a basis for study on BVDV-associated inflammatory lesions.

[Molecular detection of specific HPV types in Condylomata acuminata].

To detect HPV in genital warts (Condylomata acuminata, CA) for infection rate and association of specific HPV types between males and females, and to provide support for the development of HPV vaccines, we designed HPV type-specific oligonucleotide primers to amplify DNA fragments encoding L1 viral capsule protein. SSP-PCR was conducted in duplication for each CA sample from male and female patients. DNA of TA-cloned HPV was used as positive control, and deionized H2O was used as negative control. A total of 22 clinical samples, 13 from males and 9 from females, was collected from patients diagnosed with CA at hospitals in Beijing and Handan. HPV viral DNA was amplified in all 22 samples analyzed, with 100% detection rate. TA-cloning and sequencing of the PCR products confirmed correct amplification of HPV type-specific fragments. Of the 13 samples from males, 5 were infected with HPV6, 6 with HPV11, and 2 with HPV6 + HPV11. Of the 9 samples from females, 3 were infected with HPV6, 2 with HPV11, and 4 with both HPV6 and HPV11 infection. In addition, high-risk types HPV16, HPV18, HPV33, HPV35, HPV45, HPV54, HPV56 and HPV58 were also detected in 4 female samples that were mixed with cervical cell debris during sample collection. However, no HPV types other than HPV6 and HPV11was detected in all CA-only samples in this study. We have established a sensitive and reliable laboratory procedure for HPV detection and classification. Using the method, we reached 100% detection rate of HPV in the CA samples. Our results confirm that HPV6 and HPV11 are primarily responsible for CA, and there is no specific association of HPV types between warts in males and females.

Complete Genomic Sequences of an H3N8 Equine Influenza Virus Strain Isolated in China.

We report the complete genomic sequence of A/equine/Heilongjiang/1/2010, a strain of Florida sublineage clade 2 of H3N8 subtype equine influenza virus (EIV) isolated in northern China. This is the first announcement of a complete genomic sequence of EIV of such a clade in China.

[Progress in new vaccine strategies against influenza: a review].

Influenza, caused by influenza virus, is a serious respiratory illness which poses a global public health threat. Vaccination is the primary strategy for the prevention and control of influenza. Although both inactivated vaccines and the live attenuated vaccines are effective in preventing influenza, the current vaccines have poor efficacy in the elderly and fail to provide protection against heterosubtype viruses. Development of a safer and more effective influenza vaccine that provides broad cross protection, overcoming the intrinsic limitation of the current vaccines, has been a scientific challenge. During the past decades, structural biology, reverse genetic and other virological technologies developed quickly and sped the progress of influenza vaccinology. Some new strategies for developing influenza vaccine have been generated, produced encouraging results, which showed great prospect as next-generation of influenza vaccines.

[Rapid site-directed mutagenesis on full-length plasmid DNA by using designed restriction enzyme assisted mutagenesis].

To use the designed restriction enzyme assisted mutagenesis technique to perform rapid site-directed mutagenesis on double-stranded plasmid DNA. The target amino acid sequence was reversely translated into DNA sequences with degenerate codons, resulting in large amount of silently mutated sequences containing various restriction endonucleases (REs). Certain mutated sequence with an appropriate RE was selected as the target DNA sequence for designing mutation primers. The full-length plasmid DNA was amplified with high-fidelity Phusion DNA polymerase and the amplified product was 5' phosphorylated by T4 polynucleotide kinase and then self-ligated. After transformation into an E. coli host the transformants were rapidly screened by cutting with the designed RE. With this strategy we successfully performed the site-directed mutagenesis on an 8 kb plasmid pcDNA3.1-pIgR and recovered the wild-type amino acid sequence of human polymeric immunoglobulin receptor (pIgR). A novel site-directed mutagenesis strategy based on DREAM was developed which exploited RE as a rapid screening measure. The highly efficient, high-fidelity Phusion DNA polymerase was applied to ensure the efficient and faithful amplification of the full-length sequence of a plasmid of up to 8 kb. This rapid mutagenesis strategy avoids using any commercial site-directed mutagenesis kits, special host strains or isotopes.

An easy-to-use site-directed mutagenesis method with a designed restriction site for convenient and reliable mutant screening.

Site-directed mutagenesis (SDM) has been a very important method to probe the function-structure relationship of proteins. In this study, we introduced an easy-to-use, polymerase chain reaction (PCR)-based SDM method for double-stranded plasmid DNA, with a designed restriction site to ensure simple and efficient mutant screening. The DNA sequence to be mutated was first translated into amino acid sequence and then the amino acid sequence was reversely translated into DNA sequence with degenerate codons, resulting in a large number of sequences with silent mutations, which contained various restriction endonuclease (RE) sites. Certain mutated sequence with an appropriate RE site was selected as the target DNA sequence for designing a pair of mutation primers to amplify the full-length plasmid via inverse PCR. The amplified product was 5'-phosphorylated, circularized, and transformed into an Escherichia coli host. The transformants were screened by digesting with the designed RE. This protocol uses only one pair of primers and only one PCR is conducted, without the need for hybridization with hazardous isotope for mutant screening or subcloning step.

[Construction of anti-H5N1 virus chimeric igA antibody gene and its expression in CHO cells].

Abstract: To express human-mouse chimeric IgA antibody directed against H5N1 virus, an anti-H5N1 chimeric IgA antibody gene was constructed by joining the light and heavy chain variable region genes and the corresponding signal peptide coding sequences of the anti-H5N1 mouse monoclonal antibody H5N1-HA with the coding sequences of the constant region of the human IgA2 heavy chain and Kappa chain respectively. Then the full-length chimeric light and heavy chain expressing plasmids pEF-IGHA9 and pEF-IGK9 were constructed and transfected into the CHO/dhfr cells. The chimeric IgA antibody expression was confirmed by ELISA, SDS-PAGE and Western blotting. The successful expression of this anti-H5N1 chimeric IgA may help to provide a stand for developing passive immunological agents for H5N1 virus infection prophylaxis.

[Effect of modified NDV F48E9 strain HN gene and in vitro expression of its DNA vaccine].

Improving expression of antigen is critical to the immunogenicity of DNA vaccines. To achieve this goal, we modified the NDV F48E9 strain HN gene by optimizing the condon usage and inserting the secretary leader sequence [A/Goose/Guangdong/1/96 (H5N1) HA gene, Accession No. AF144305]. The HN gene modified and knocked the signal peptide off were named SoptiHN and optiHN. The three sequence: SoptiHN, optiHN and the NDV F48E9 strain HN gene were inserted into the vector pVAX1 and vector pVAX1-CpG including CpG-ODN sequence respectively. Then we got six recombinant plasmids: pV-SoptiHN, pVC-SoptiHN, pV-optiHN, pVC-optiHN, pV-HN and pVC-HN. By optimizing condon usage in transiently transfected 293T cells, expression levels of HN gene were higher from the codon-optimized gene than the counterpart. Moreover, both optimization of condon usage and addition of signal peptide could improve expression of HN gene in vitro.

[Preparation and primary analysis of monoclonal antibodies against VP5 protein of chicken infectious bursal disease virus].

Infectious bursal disease virus (IBDV), the causative agent of a highly contagious disease in chickens, carries a small nonstructural protein (NS). In this study, vvIBDV Gx-VP5 genes were cloned into plasmid pET30a( + ) and expressed in E. coli with IPTG inducing. BALB/c mice were immunized with the purified recombinant fusion protein. SP2/0 myeloma cells and spleen cells of BALB/c mice were fused by PEG(MW1500), three hybridoma cell lines were examined by indirect ELISA and clone for three times by limited dilution, and were named as 4B4, 6D12, 3E8. The subtype of the monoclonal antibodies were IgG1 with a subtype identified ELISA kit, and light chains were kappa. The ascites titers of monoclonal antibodies were 5 x 10(4), 3.5 x 10(4), 3 x 10(4) by indirect ELISA, respectively. Indirect ELISA and Western blot results showed that the monoclonal antibodies only acted with VP5 protein, IF analysis indicated that three monoclonal antibodies acted with IBDV Gt. There were specific fluorescence in detected Vero E6 cells which transient expressed VP5 protein by IFA. Therefore, monoclonal antibodies specific to IBDV VP5 proteins are specific method for detected VP5 proteins, and base on establish stabilize expressed VP5 protein Vero cell lines to research IBDV VP5 protein function.