The whole genomic analysis of orf virus strain HN3/12 isolated from Henan province, central China

Screening and characterization of a novel linear B-cell epitope on orf virus F1L protein

Background

Orf, also known as contagious ecthyma (CE), is an acute, contagious zoonotic disease caused by the orf virus (ORFV). The F1L protein is a major immunodominant protein on the surface of ORFV and can induce the production of neutralizing antibodies.

Methods

The prokaryotic expression system was used to produce the recombinant F1L protein of ORFV, which was subsequently purified and used to immunize mice. Positive hybridoma clones were screened using an indirect enzyme-linked immunosorbent assay (ELISA). The reactivity and specificity of the monoclonal antibody (mAb) were verified through Western blot and indirect immunofluorescence (IFA). The linear antigenic epitope specific to the mAb was identified through Western blot, using truncated F1L proteins expressed in eukaryotic cells. A multiple sequence alignment of the ORFV reference strains was performed to evaluate the degree of conservation of the identified epitope.

Results

After three rounds of subcloning, a mAb named Ba-F1L was produced. Ba-F1L was found to react with both the exogenously expressed F1L protein and the native F1L protein from ORFV-infected cells, as confirmed by Western blot and IFA. The mAb recognized the core epitope 103CKSTCPKEM111, which is highly conserved among various ORFV strains, as shown by homologous sequence alignment.

Conclusion

The mAb produced in the present study can be used as a diagnostic reagent for detecting ORFV and as a basic tool for exploring the mechanisms of orf pathogenesis. In addition, the identified linear epitope may be valuable for the development of epitope-based vaccines.

Molecular detection and phylogenetic analysis of Orf viruses from goats in Jiangxi province, China

Orf is a zoonosis caused by the Orf virus (ORFV), which is endemic in goats, sheep, and wild ruminants worldwide. Orf infection is prevalent in China, with outbreaks reported in several provinces. Currently, there is limited information available regarding the characterization of ORFV strains in Jiangxi province. This study investigated an acute outbreak of Orf that occurred in 2021 in a goat herd in the Jiangxi province of China. Clinical signs in this case included lesions on the lips, nose, and inside the mouth. The presence of ORFV was confirmed from tissue samples by polymerase chain reaction (PCR). The nucleotide sequences of the B2L and F1L genes were fully sequenced and used to construct phylogenetic trees. The results of this investigation identified the ORFV JXxy2021 as the cause of the outbreak. The phylogenetic analysis revealed that the ORFV strain JXxy2021 had the highest similarity to the ORFV strains GO and FJ-SL from the neighboring province of Fujian. This suggests that JXxy2021 was likely transmitted from Fujian province. The results have provided valuable information on the genetic characteristics of JXxy2021 and the endemic situations of Orf in China.

The Global Evolutionary History of Orf Virus in Sheep and Goats Revealed by Whole Genomes Data

Orf virus (ORFV) belongs to the genus Parapoxvirus (Poxviridae family). It is the causative agent of contagious ecthyma (CE) that is an economically detrimental disease affecting small ruminants globally. Contagious ecthyma outbreaks are usually reported in intensive breeding of sheep and goats but they have also been reported in wildlife species. Notably, ORFV can infect humans, leading to a zoonotic disease. This study aims to elucidate the global evolutionary history of ORFV genomes in sheep and goats, including the first genomes from Central America in the analyses. In comparison to the last study on ORFV whole genomes, the database now includes 11 more sheep and goat genomes, representing an increase of 42%. The analysis of such a broader database made it possible to obtain a fine molecular dating of the coalescent time for ORFV S and G genomes, further highlighting the genetic structuring between sheep and goat genomes and corroborating their emergence in the latter half of 20th century.

The whole genomic analysis of the Orf virus strains ORFV-SC and ORFV-SC1 from the Sichuan province and their weak pathological response in rabbits

The Orf virus (ORFV) is a member of the Parapoxvirus genus of the Poxviridae family and can cause contagious diseases in sheep, goats, and wild ungulates. In the present study, two ORFV isolates (ORFV-SC isolated from Sichuan province and ORFV-SC1 produced by 60 passages of ORFV-SC in cells) were sequenced and compared to multiple ORFVs. The two ORFV sequences had entire genome sizes of 14,0707 bp and 141,154 bp, respectively, containing 130 and 131 genes, with a G + C content of 63% for the ORFV-SC sequence and 63.9% for the ORFV-SC1 sequence. Alignment of ORFV-SC and ORFV-SC1 with five other ORFV isolates revealed that ORFV-SC, ORFV-SC1, and NA1/11 shared > 95% nucleotide identity with 109 genes. Five genes (ORF007, ORF20, ORF080, ORF112, ORF116) have low amino acids identity between ORFV-SC and ORFV-SC1. Mutations in amino acids result in changes in the secondary and tertiary structure of ORF007, ORF020, and ORF112 proteins. The phylogenetic tree based on the complete genome sequence and 37 single genes revealed that the two ORFV isolates originated from sheep. Finally, animal experiments demonstrated that ORFV-SC1 is less harmful to rabbits than ORFV-SC. The exploration of two full-length viral genome sequences provides valuable information in ORFV biology and epidemiology research. Furthermore, ORFV-SC1 demonstrated an acceptable safety profile following animal vaccination, indicating its potential as a live ORFV vaccine.

Genome-Wide Analysis and Molecular Characterization of Orf Virus Strain UPM/HSN-20 Isolated From Goat in Malaysia

Contagious ecthyma commonly known as Orf is a globally important, highly contagious zoonotic, transboundary disease that affects domestic and wild ruminants. The disease is of great economic significance causing an immense impact on animal health, welfare, productivity, and trade. Detailed analysis of the viral genome is crucial to further elucidate the molecular mechanism of Orf virus (ORFV) pathogenesis. In the present study, a confluent monolayer of lamb testicle cells was infected with the processed scab sample obtained from an infected goat. The presence of the virus was confirmed using polymerase chain reaction and electron microscopy, while its genome was sequenced using next-generation sequencing technology. The genome sequence of Malaysian ORFV strain UPM/HSN-20 was found to contain 132,124 bp with a G + C content of 63.7%. The homology analysis indicates that UPM/HSN-20 has a high level of identity 97.3–99.0% with the other reference ORFV strain. Phylogenetic analysis revealed that ORFV strain UPM/HSN-20 is genetically more closely related to ORFV strain XY and NP from China. The availability of the genome-wide analysis of ORFV UPM/HSN-20 strain from Malaysia will serve as a good platform for further understanding of genetic diversity, ORFV infection, and strategic development for control measures.

Complete genomic sequences and comparative analysis of two Orf virus isolates from Guizhou Province and Jilin Province, China

Orf virus (ORFV, species Orf virus) belongs to the typical species of the Parapoxvirus genus of the family Poxviridae, which infects sheep, goats, and humans with worldwide distribution. Although outbreaks of Orf have been reported sequentially in several Chinese provinces, the epidemiology of Orf and genetic diversity of ORFV strains still needs to be further characterized. To further reveal the genomic organization of the ORFV-GZ18 and ORFV-CL18 isolates, the complete genome sequences of two recently obtained ORFV isolates were sequenced using the next-generation sequencing technology and analyzed, which had been deposited in the GenBank database under accession number MN648218 and MN648219, respectively. The complete genomic sequence of ORFV-CL18 was 138,495 bp in length, including 131 potential open reading frames (ORFs) flanked by inverted terminal repeats (ITRs) of 3481 bp at both ends, which has genomic structure typical Parapoxviruses. The overall genomic organization of the fully sequenced genome of ORFV-GZ18 was consistent with ORFV-CL18 genome, with a complete genome size of 138,446 nucleotides, containing 131 ORFs flanked by ITRs of 3469 bp. Additionally, the overall G + C contents of ORFV-GZ18 and ORFV-CL18 genome sequences were about 63.9% and 63.8%, respectively. The phylogenetic analysis showed that both ORFV-GZ18 and ORFV-CL18 were genetically closely related to ORFV-SY17 derived from sheep. In summary, the complete genomic sequences of ORFV-GZ18 and ORFV-CL18 are reported, with the hope it will be useful to investigate the host range, geographic distribution, and genetic evolution of the virus in Southern West and Northern East China.

Genomic Features and Evolution of the Parapoxvirus during the Past Two Decades

Parapoxvirus (PPV) has been identified in some mammals and poses a great threat to both the livestock production and public health. However, the prevalence and evolution of this virus are still not fully understood. Here, we performed an in silico analysis to investigate the genomic features and evolution of PPVs. We noticed that although there were significant differences of GC contents between orf virus (ORFV) and other three species of PPVs, all PPVs showed almost identical nucleotide bias, that is GC richness. The structural analysis of PPV genomes showed the divergence of different PPV species, which may be due to the specific adaptation to their natural hosts. Additionally, we estimated the phylogenetic diversity of seven different genes of PPV. According to all available sequences, our results suggested that during 2010–2018, ORFV was the dominant virus species under the selective pressure of the optimal gene patterns. Furthermore, we found the substitution rates ranged from 3.56 × 10⁻⁵ to 4.21 × 10⁻⁴ in different PPV segments, and the PPV VIR gene evolved at the highest substitution rate. In these seven protein-coding regions, purifying selection was the major evolutionary pressure, while the GIF and VIR genes suffered the greatest positive selection pressure. These results may provide useful knowledge on the virus genetic evolution from a new perspective which could help to create prevention and control strategies.

Genomic characterization of two Orf virus isolates from Jilin province in China

Orf virus (ORFV), a typical member of the Parapoxvirus genus within the family Poxviridae, which is the causative agent of Orf, a common epitheliotropic viral disease of sheep, goats, wild ruminants, and humans. In the present study, we sequenced the complete genomic sequences of two ORFV strains (ORFV-SY17, isolated from sheep, and ORFV-NA17, isolated from goat) and conducted the comparative analysis of multiple ORFVs. The complete genomic sequence of ORFV-SY17 was at length of 140,413 bp, including 131 potential open reading frames (ORFs) flanked by inverted terminal repeats (ITRs) of 4267 bp at both ends. The ORFV-NA17 strain displayed the similar genome structure with ORFV-SY17. The whole genomic sequence of ORFV-NA17 strain was 139,287 bp in length and contained 132 ORFs flanked by ITRs of 3974 bp. The overall G+C contents of ORFV-SY17 and ORFV-NA17 genome sequences were about 63.8% and 63.7%, respectively. The ITR sequences analysis showed that ORFV-SY17 and ORFV-NA17 contained the terminal BamHI sites and conserved telomere resolution sequences at both ends of their genome. In addition, comparative analysis of ORFs among ORFV-SY17, ORFV-NA17, and other ORFV strains revealed several sequence variations caused by insertions or deletions, especially in ORFs 005 and 116, which were very likely associated with host species. Phylogenetic analysis based on the complete genome sequences revealed that ORFV-SY17 was genetically closely related to NA1/11 and HN3/12 strains derived from sheep, while ORFV-NA17 was closely related to YX strain derived from goat. The multiple alignment of deduced amino acid sequences further revealed the genetic relationship between host species and genetic variations of ORFV strains. Taken together, the availability of genomic sequences of ORFV-SY17 and ORFV-NA17 strains from Jilin Province will aid in our understanding of the genetic diversity and evolution of ORFV strains in this region and can assist in distinguishing between ORFV strains that originate in sheep and goats.

Orf virus: A promising new therapeutic agent

The orf virus (ORFV) is a zoonotic, epitheliotropic, DNA parapoxvirus that infects principally sheep and goats. Exposure of animals to the virus or immunization by an ORFV preparation can accentuate the severity of disease, which has provoked an interest in the underlying cellular, virological, and molecular mechanisms. The identified ORFV virulence genes and the fact that the virus can repeatedly infect a host, owing to its evasive mechanisms, contribute to the development of potent immune modulators in various animal species. ORFV has been developed as a vaccine in veterinary medicine. The unique host immune-evasion ability of ORFV has made it an important candidate for vaccine vectors and biological agents (as an oncolytic virus). Genetic modifications using ORFV to obtain safe and efficient preparations and mechanistic studies are improvements to the currently available methods for disease treatment.