An in-depth bioinformatic analysis of the novel recombinant lumpy skin disease virus strains: from unique patterns to established lineage

Screening and identification of LSDV-specific monoclonal antibodies to establish a double-antibody sandwich ELISA for distinguishing LSDV from SPPV and GTPV

Lumpy skin disease caused by the lumpy skin disease virus (LSDV) infection causes significant economic losses to the cattle industry in many countries worldwide. The genetic homology between LSDV and both goat pox virus (GTPV) and sheep pox virus (SPPV) can reach around 97 %, indicating a high level of serological similarity. This serological resemblance makes it difficult to differentiate between LSD and GTP or SPP via serological methods, which significantly challenges the detection and diagnosis of LSD. For the serological differential diagnosis of LSDV, we prepared and identified two LSDV-specific monoclonal antibodies 3C10 and 6H3. The results showed that both monoclonal antibodies targeted the P32 protein of LSDV. A double-antibody sandwich ELISA was established based on the LSDV monoclonal antibodies 3C10 and 6H3-HRP, which have good sensitivity and specificity for diagnosing LSDV and do not cross-react with many common viruses in cattle and sheep, including GTPV and SPPV. To summarize, LSDV-specific monoclonal antibodies that can distinguish LSDV from GTPV and SPPV were developed and can be used for the differential diagnosis of LSD and to study the pathogenic mechanism of the virus.

Whole Genome Sequencing of Lumpy Skin Disease Virus from 2021-2023 in Eastern Eurasia Reveals No More Recombination Signals in the Circulating Pool of Strains

Having spanned thousands of kilometers from Africa through Europe, the Middle East, Central Asia through to the south eastern part of Eurasia in the recent decade, lumpy skin disease virus has now become entrenched in China, Thailand, Vietnam, and South Korea. In light of discovered findings on recombination, cluster 2.5 lineage strains are now dominant and continue to spread throughout Southeast Asia. To gain a better picture of the phylogenetic landscape in the field, whole genome sequencing of 11 LSDV isolates from Russia and Mongolia collected from 2021 to 2023 has been attempted to see the dynamics of recombination signals, as was shown for LSDV circulating in 2017-2019 in Russia and Kazakhstan. Deep sequencing performed direct from skin nodules along with data retrieved from Genbank provides the most recent update on molecular epidemiology of LSDV and demonstrates that no more mosaic variant of LSDV has been observed, and cluster 2.5 lineage is now the dominant lineage currently on the rise in the region with its own patterns of monophyletic evolution. These discoveries may help future investigations aimed at epidemiological surveillance and virus tracking in the context of currently identified lineages worldwide.

Progress in diagnostic methods and vaccines for lumpy skin disease virus: a path towards understanding the disease

Lumpy skin disease (LSD) is caused by Lumpy Skin disease virus (LSDV) belonging to the genus Capripoxvirus (CaPV). The disease is widespread in Africa, the Middle East and Asia and has been present in Egypt since 1988. LSD is mainly transmitted by blood-sucking insects. LSD is clinically distinguished by a high fever, skin nodules, and swollen Lymph nodes. Detecting sub-clinical disease can be challenging however, prompt laboratory investigations are vital. Skin lesions are the main source of infection, although the virus is shed through many excretions and discharges including semen. Disease confirmation in clinical laboratories includes detection of viral nucleic acid, antigen and antibody levels. Simple, adaptable, and quick assays for detecting LSDV are required for control measures. Vaccination, together with controlled quarantine and vector control measures, may be beneficial for preventing disease spread. Presently, a range of live attenuated vaccines, have been used in the field with different levels of protection and side effects. With high levels of vaccination coverage, attenuated Neethling vaccines have successfully eradicated of LSDV in Europe. Inactivated LSDV vaccines have also been demonstrated effective in experimental infections. Furthermore, due to its large genome, LSDV is being exploited as a vaccine delivery element, generating an innovative composite with additional viral genes by DNA recombination. Vaccines developed on this basis have the potential to prevent a wide range of diseases and have been demonstrated to be effective in experimental settings. In this review, we emphasizethe advances in diagnostic methods and vaccines developed last decade, thereby providing a basis for future research into various aspects of LSDV and providing information for possibility of disease elimination.

Genetic characterization of lumpy skin disease virus (LSDV) isolates from an outbreak on Great Nicobar Island, India, in 2022 reveals the involvement of a cluster 2.5 recombinant LSDV strain (East/Southeast Asian lineage)

Lumpy skin disease (LSD) has emerged as a global threat to cattle health and production. Although India has been encountering regular episodes of LSD epidemics on the mainland since 2019, the Andaman and Nicobar Islands remained free of LSD until 2021. In this study, we investigated the first LSD outbreak on Great Nicobar Island in 2022 and examined the genetic characteristics of the LSDV strain associated with this outbreak. The morbidity and mortality rates in cattle were 38.29% and 1.89%, respectively. We screened 123 samples (whole blood, nasal swab, or skin tissue) from 111 cattle by LSDV real-time PCR and sera from 86 cattle by LSDV antibody ELISA, and the results confirmed LSDV infection. Subsequent nucleotide sequencing and phylogenetic analysis of five selected marker genes (GPCR, RPO30, P32, EEV, and B22R) revealed that the LSDV strain from Great Nicobar Island resembled cluster 2.5 LSDV recombinant strains from East and Southeast Asia but was distinct from wild-type LSDV strains (1.2.1, 1.2.2) circulating in mainland India, indicating an exotic source of introduction. Phylogenetic analysis using a concatenated sequence (GPCR-RPO30-P32-EEV-B22R) showed that both the wild-type and recombinant LSDV strains formed well-supported clusters, indicating that this type of analysis may be used as an alternative to whole-genome sequence analysis. We also found that determination of the nucleotide sequence of the C-terminal 717 bp of the B22R gene may be sufficient for reliable assignment of circulating LSDV isolates to a particular cluster. This is the first report of the detection of a recombinant LSDV strain in India, demonstrating the spread of cluster 2.5 recombinant LSDV further into South Asia. Our findings highlight the value of LSDV surveillance and genetic analysis for LSDV epidemiology, which may be helpful for developing effective control strategies.

Development of a Multi-Locus Real-Time PCR with a High-Resolution Melting Assay to Differentiate Wild-Type, Asian Recombinant, and Vaccine Strains of Lumpy Skin Disease Virus

Lumpy skin disease virus (LSDV) affects cattle and causes significant economic damage. The live vaccine derived from an attenuated strain is effective but is associated with mild disease and skin lesions in some vaccinated cattle. Moreover, recombinant LSDV strains, particularly one with wild-type field and vaccine strains, have recently emerged and spread throughout Asian countries. A cost-effective LSDV typing method is required. We developed a multi-locus real-time PCR with a high-resolution melting (HRM) assay to differentiate between the wild-type, vaccine, and dominant Asian recombinant strains. Based on a multiple alignment analysis, we selected three target genes for the HRM assay, ORF095, ORF126, and ORF145, in which there are insertions/deletions and nucleotide substitutions between wild-type and vaccine strains, and designed primer sets for the assay. Using the synthetic DNA encoding these genes for the two strains, it was shown that the PCR amplicons intercalated with a saturating fluorescent dye could clearly differentiate between wild-type and vaccine strains in the HRM analysis for all three target genes. Further, using clinical samples, our method was able to identify recombinant strains harboring the wild-type ORF095 and ORF145 and the vaccine strain ORF126 genes. Thus, our HRM assay may provide rapid LSDV typing.

Genetic Evolutionary Analysis of Lumpy Skin Disease Virus Strain Under Immune Pressure Exerted by Heterologous Goat Poxvirus Vaccines

Lumpy skin disease (LSD) is an important infectious disease that threatens the global cattle industry. Recently, LSD has occurred frequently in Asia. The attenuated goat poxvirus (GTPV) vaccine is widely used to prevent LSD in cattle in China; however, sporadic cases of LSD still occur in immunized cattle. This study aimed to investigate the genetic evolution of isolated LSD virus (LSDV) strain under GTPV heterologous vaccine immune pressure. We isolated a new strain of LSDV, named LSDV/China/SX/2023, from a cattle herd immunized with a GTPV-attenuated vaccine in Shaanxi Province, Northwest China, and conducted whole-genome sequencing and genetic evolution studies. There are several open reading frames (ORFs) differences between the isolated strain and the Chinese reference strains, among which truncated expression of the Kelch-like protein encoded by ORF 19 may affect its growth characteristics. Phylogenetic analysis revealed that the isolated strain is in the same evolutionary clade as previous isolates from China and Southeast Asia. RDP4 and Simplot simultaneously showed that all strains in this branch had the same 15 recombination events, and there was one recombination event associated with the GTPV. This study presents the recent genetic evolution of LSDV under GTPV vaccine immune pressure and discusses the viral recombination events that are thought to influence transmission which are critical for the control and purification of LSD.

Lumpy Skin Disease: Insights into Molecular Pathogenesis and Control Strategies

Lumpy skin disease (LSD) is a viral infection that affects buffaloes and cattle across various regions, including both tropical and temperate climates. Intriguingly, the virus-carrying skin sores remain the primary source of infection for extended periods, exacerbated by the abundance of vectors in disease-endemic countries. Recent scientific advances have revealed the molecular aspects of LSD and offered improved vaccines and valuable antiviral targets. This review summarizes the molecular features of LSD and its effect on various livestock species. We then provide an extensive discussion on the transmission dynamics of LSD and the roles of vectors in its continued spread among livestock populations. Additionally, this review critically analyses the rationales behind, as well as the affordability and effectiveness, of current control strategies worldwide.

Detection and molecular characterization of lumpy skin disease and bovine papular stomatitis viruses in lumpy skin disease-suspected outbreaks in Tanzania

BACKGROUND

Lumpy Skin Disease (LSD) is endemic in sub-Saharan countries and is currently a global threat to the cattle industry. Information on the circulating Capripoxvirus lumpyskinpox, formerly known as Lumpy Skin Disease Virus (LSDV), and other poxviruses infecting cattle is very scant in Tanzania. The current study aimed to confirm and characterize LSDV and other poxviruses infecting cattle, from LSD suspected outbreaks in Tanzania.

METHODS

A total of 24 samples were collected from four LSD suspected outbreaks reported in Tanzania between February and May 2023. Samples were screened for LSDV genome by real-time PCR and then subjected to a high-resolution multiplex melting (HRM) assay where 10 samples were positive for Capripoxvirus (CaPV) and one sample was Parapoxvirus (PPV) positive. Four LSDV genes; RPO30, GPCR, EEV glycoprotein and B22R and the partial B2L gene of PPVs were analyzed.

RESULTS

All targeted LSDV genes from the Tanzanian isolates showed 100% similarity and isolates clustered with commonly circulating LSDV field isolates. Furthermore, the single nucleotide polymorphism (SNP) at position 240 (A-> G) of the EEV gene differentiates the Tanzanian LSDVs from the group of ancient Kenyan LSDV isolates while the B22R sequences of the Tanzanian LSDV isolates differed from the LSDV Neethling and LSDV KSGP-0240 derived vaccines. Sequence analysis of the partial B2L gene of the Tanzanian parapoxvirus bovinestomatitis, formerly known as Bovine papular stomatitis virus (BPSV) showed a different BPSV strain circulating compared to publicly available sequences.

CONCLUSION

These findings confirm the presence of LSDV in Tanzania, which suggesting the need for establishing an effective control program and continuous monitoring. The presence of a typical profile for Tanzania BPSV is an indication that, although never reported before, BPSV is established in the country therefore this virus should be included in the differential diagnosis of LSDV.

An Attenuated Vaccine Virus of the Neethling Lineage Protects Cattle against the Virulent Recombinant Vaccine-like Isolate of the Lumpy Skin Disease Virus Belonging to the Currently Established Cluster 2.5

Lumpy skin disease (LSD) is an emerging transboundary and highly infectious viral disease mainly affecting cattle. The fact that it was initially confined to Africa and then spread beyond its geographical range to other regions, including the Middle East, Turkey, Europe, the Balkans, Russia and Asia, is an indication of the underestimation and neglect of this disease. Vaccination is considered the most effective way to control the spread of LSDV, when combined with other control measures. LSD is now on the rise in Southeast Asia, where the circulating virus belongs to recombinant lineage 2.5. In this study, we evaluated the efficacy of an attenuated LSDV strain belonging to the Neethling cluster 1.1 by challenge with a virulent recombinant vaccine-like LSDV isolate "Mongolia/2021" belonging to cluster 2.5. Some of the vaccinated animals showed an increase in body temperature of 1-1.5 °C above the physiological norm, without clinical signs, local reactions, vaccine-induced viremia or generalization, demonstrating the efficacy and safety of the vaccine strain against a recombinant strain. Furthermore, all the vaccinated animals showed strong immune responses, indicating a high level of immunogenicity. However, the control group challenged with "Mongolia/2021" LSD showed moderate to severe clinical signs seen in an outbreak, with high levels of virus shedding in blood samples and nasal swabs. Overall, the results of the present study demonstrate that the attenuated LSDV Neethling strain vaccine has a promising protective phenotype against the circulating strains, suggesting its potential as an effective tool for the containment and control of LSD in affected countries from Southeast Asia.

Subclinical infection caused by a recombinant vaccine-like strain poses high risks of lumpy skin disease virus transmission

Lumpy skin disease (LSD) is a transboundary viral infection, affecting cattle with characteristic manifestations involving multiple body systems. A distinctive characteristic of lumpy skin disease is the subclinical disease manifestation wherein animals have viremia and shed the virus through nasal and ocular discharges, while exhibiting no nodules but enlarged lymph nodes that are easily oversighted by inexperienced vets. Further research on the role of subclinically ill animals in the transmission of LSD virus (LSDV) can contribute to the development of more effective tools to control the disease worldwide. Thus, this study aims to determine the potential role of subclinical infection in virus transmission in a non-vector-borne manner. To achieve this, we inoculated animals with the recombinant vaccine-like strain (RVLS) Udmurtiya/2019 to cause clinical and subclinical LSDV infection. After the disease manifestation, we relocated the subclinically ill animals to a new clean facility followed by the introduction of another five animals to determine the role of RVLS-induced subclinical infection in the virus transmission via direct/indirect contact. After the introduction of the naïve animals to the relocated subclinically ill ones in a shared airspace, two introduced animals contracted the virus (clinically and subclinically), showing symptoms of fever, viremia, and seroconversion in one animal, while three other introduced animals remained healthy and PCR-negative until the end of the study. In general, the findings of this study suggest the importance of considering LSDV subclinical infection as a high-risk condition in disease management and outbreak investigations.

Genomic analysis of lumpy skin disease virus asian variants and evaluation of its cellular tropism

Lumpy skin disease virus (LSDV) is a poxvirus that mainly affects cattle and can lead to symptoms such as severe reduction in milk production as well as infertility and mortality, which has resulted in dramatic economic loss in affected countries in Africa, Europe, and Asia. In this study, we successfully isolated two strains of LSDV from different geographical regions in China. Comparative genomic analyses were performed by incorporating additional LSDV whole genome sequences reported in other areas of Asia. Our analyses revealed that LSDV exhibited an 'open' pan-genome. Phylogenetic analysis unveiled distinct branches of LSDV evolution, signifying the prevalence of multiple lineages of LSDV across various regions in Asia. In addition, a reporter LSDV expressing eGFP directed by a synthetic poxvirus promoter was generated and used to evaluate the cell tropism of LSDV in various mammalian and avian cell lines. Our results demonstrated that LSDV replicated efficiently in several mammalian cell lines, including human A549 cells. In conclusion, our results underscore the necessity for strengthening LSD outbreak control measures and continuous epidemiological surveillance.

Genome sequence characterization of the unique recombinant vaccine-like lumpy skin disease virus strain Kurgan/2018

In 2018, the molecular epidemiology of lumpy skin disease in Russia was characterized by a surge in novel recombinant vaccine-like strains causing outbreaks along the southern border, spreading in an easterly direction. Currently, five distinct novel recombinant vaccine-like lineages have been described, designated as clusters 2.1 to 2.5. Based on the complete genome sequence analysis of the causative lumpy skin disease virus (Kurgan/Russia/2018), obtained from an eponymous outbreak, the genome was shown to be composed of a Neethling vaccine strain virus as the dominant parental strain and KSGPO vaccine virus as its minor parental strain. These features are similar to those of Saratov/Russia/2017 and Tyumen/Russia/2018, representing clusters 2.1 and 2.4, respectively. However, Kurgan/Russia/2018 has 16 statistically significant recombination events unique to this sequence, contributing to the phylogenetic clustering of Kurgan/Russia/2018 in yet another cluster designed cluster 2.6, based on analysis involving the complete genome sequences.

Complete genome reconstruction of the global and European regional dispersal history of the lumpy skin disease virus

IMPORTANCE

Lumpy skin disease virus (LSDV) has a complex epidemiology involving multiple strains, recombination, and vaccination. Its DNA genome provides limited genetic variation to trace outbreaks in space and time. Sequencing of LSDV whole genomes has also been patchy at global and regional scales. Here, we provide the first fine-grained whole genome sequence sampling of a constrained LSDV outbreak (southeastern Europe, 2015-2017), which we analyze along with global publicly available genomes. We formally evaluate the past occurrence of recombination events as well as the temporal signal that is required for calibrating molecular clock models and subsequently conduct a time-calibrated spatially explicit phylogeographic reconstruction. Our study further illustrates the importance of accounting for recombination events before reconstructing global and regional dynamics of DNA viruses. More LSDV whole genomes from endemic areas are needed to obtain a comprehensive understanding of global LSDV dispersal dynamics.

Sign of APOBEC editing, purifying selection, frameshift, and in-frame nonsense mutations in the microevolution of lumpy skin disease virus

The lumpy skin disease virus (LSDV), which mostly affects ruminants and causes huge-economic loss, was endemic in Africa, caused outbreaks in the Middle East, and was recently detected in Russia, Serbia, Greece, Bulgaria, Kazakhstan, China, Taiwan, Vietnam, Thailand, and India. However, the role of evolutionary drivers such as codon selection, negative/purifying selection, APOBEC editing, and genetic variations such as frameshift and in-frame nonsense mutations in the LSDVs, which cause outbreaks in cattle in various countries, are still largely unknown. In the present study, a frameshift mutation in LSDV035, LSDV019, LSDV134, and LSDV144 genes and in-frame non-sense mutations in LSDV026, LSDV086, LSDV087, LSDV114, LSDV130, LSDV131, LSDV145, LSDV154, LSDV155, LSDV057, and LSDV081 genes were revealed among different clusters. Based on the available complete genome sequences, the prototype wild-type cluster-1.2.1 virus has been found in other than Africa only in India, the wild-type cluster-1.2.2 virus found in Africa were spread outside Africa, and the recombinant viruses spreading only in Asia and Russia. Although LSD viruses circulating in different countries form a specific cluster, the viruses detected in each specific country are distinguished by frameshift and in-frame nonsense mutations. Furthermore, the present study has brought to light that the selection pressure for codons usage bias is mostly exerted by purifying selection, and this process is possibly caused by APOBEC editing. Overall, the present study sheds light on microevolutions in LSDV, expected to help in future studies towards disturbed ORFs, epidemiological diagnostics, attenuation/vaccine reverts, and predicting the evolutionary direction of LSDVs.

Lumpy skin disease: history, current understanding and research gaps in the context of recent geographic expansion

Lumpy skin disease is recognized as a transboundary and emerging disease of cattle, buffaloes and other wild ruminants. Being initially restricted to Africa, and since 1989 the Middle East, the unprecedented recent spread across Eurasia demonstrates how underestimated and neglected this disease is. The initial identification of the causative agent of LSD as a poxvirus called LSD virus, was well as findings on LSDV transmission and epidemiology were pioneered at Onderstepoort, South Africa, from as early as the 1940s by researchers such as Weiss, Haig and Alexander. As more data emerges from an ever-increasing number of epidemiological studies, previously emphasized research gaps are being revisited and discussed. The currently available knowledge is in agreement with the previously described South African research experience that LSDV transmission can occur by multiple routes, including indirect contact, shared water sources and arthropods. The virus population is prone to molecular evolution, generating novel phylogenetically distinct variants resulting from a diverse range of selective pressures, including recombination between field and homologous vaccine strains in cell culture that produce virulent recombinants which pose diagnostic challenges. Host restriction is not limited to livestock, with certain wild ruminants being susceptible, with unknown consequences for the epidemiology of the disease.

Constitutive proteins of lumpy skin disease virion assessed by next-generation proteomics

IMPORTANCE

Lumpy skin disease virus (LSDV) is the causative agent of an economically important cattle disease which is notifiable to the World Organisation for Animal Health. Over the past decades, the disease has spread at an alarming rate throughout the African continent, the Middle East, Eastern Europe, the Russian Federation, and many Asian countries. While multiple LDSV whole genomes have made further genetic comparative analyses possible, knowledge on the protein composition of the LSDV particle remains lacking. This study provides for the first time a comprehensive proteomic analysis of an infectious LSDV particle, prompting new efforts toward further proteomic LSDV strain characterization. Furthermore, this first incursion within the capripoxvirus proteome represents one of very few proteomic studies beyond the sole Orthopoxvirus genus, for which most of the proteomics studies have been performed. Providing new information about other chordopoxviruses may contribute to shedding new light on protein composition within the Poxviridae family.

Development and application of a real-time polymerase chain reaction assay to detect lumpy skin disease virus belonging to the Kenyan sheep and goat pox group

Lumpy skin disease (LSD) outbreaks in Southeast and South Asia are attributed to different lineages of LSD virus (LSDV). Variants belonging to the novel recombinant cluster 2.5 circulate in China and Thailand, while a Kenyan sheep and goat pox (KSGP) strain from cluster 1.1 circulates in India, Pakistan, and Bangladesh. The clusters representing these circulating strains are vastly different. However, if their distribution encroaches into each other's ranges, it will be impossible to differentiate between them due to the lack of suitable molecular tools. Thus, fit-for-purpose molecular tools are in demand to effectively and timeously diagnose and investigate the epidemiology of LSDVs in a region. These could significantly contribute to the phylogenetic delineation of LSDVs and the development of preventive measures against transboundary spillovers. This work aimed to develop a real-time polymerase chain reaction assay targeting open reading frame LW032, capable of specifically detecting KSGP-related isolates and recombinant LSDV strains containing the KSGP backbone. The analytical specificity was proven against the widest possible panel of recombinant vaccine-like LSDV strains known to date. The amplification efficiency was 91.08%, and the assay repeatability had a cycle threshold variation of 0.56-1.1 over five repetitions across three runs. This KSGP-specific assay is reliable and fast and is recommended for use in LSDV epidemiological studies where the accurate detection of KSGP genetic signatures is a priority, particularly in regions where KSGP-like and other lineages are circulating.

Comparison of Gross Pathology between Classical and Recombinant Lumpy Skin Disease Viruses

The pathology caused by three different isolates of lumpy skin disease virus, classical field cluster 1.2 strain Dagestan/2015, recombinant vaccine-like cluster 2.1 strain Saratov/2017, and cluster 2.2 strain Udmurtiya/2019, in cattle was compared from experimental infections. The infection of cattle was performed using intravenous administration of 2 mL of 105 TCID50/mL of each specific LSDV. Both classical and recombinant forms of LSDV cause pathological changes in the skin and lymph nodes, as well as the trachea and lungs. Due to circulatory disorders in the affected organs, multiple areas of tissue necrosis were observed, which, with the resurgence of secondary microflora, led to the development of purulent inflammation. Observed pathological changes caused by the recombinant vaccine-like strain Udmurtiya/2019 were characterized by a more pronounced manifestation of the pathoanatomical picture compared to the classical field strains Dagestan/2015 and Saratov/2017. Interestingly, Dagestan/2015 and Udmurtiya/2019 caused damage to the lymph nodes, characterized by serous inflammation and focal purulent lymphadenitis caused by purulent microflora. "Saratov/2017" did not cause pathology in the lymph nodes. All LSDVs were virulent and caused pathology, which was not distinguishable between viruses. This data set will serve as the experimentally validated basis for the comparative examination of novel LSDV strains in gross pathology.

Phylogenetic and pathogenic characterization of lumpy skin disease virus circulating in China

The genomic characterization of emerging pathogens is critical for unraveling their origin and tracking their dissemination. Lumpy skin disease virus (LSDV) is a rapidly emerging pathogen in Asia including China. Although the first Lumpy skin disease (LSD) outbreak was reported in 2019, the origin, transmission, and evolutionary trajectory of LSDV in China have remained obscure. The viral genome of a circulating LSDV strain in China, abbreviated LSDV/FJ/CHA/2021, was sequenced using the next-generation sequencing technique. The morphology and cytoplasmic viral factory of these LSDV isolates were observed using transmission electron microscopy. Subsequently, the genomic characterization of this LSDV isolate was systematically analyzed for the first time using the bioinformatics software. The current study revealed that several mutations in the genome of LSDV isolates circulating in China were identified using single nucleotide polymorphisms (SNPs) analysis, an instrument to evaluate for continuous adaptive evaluation of a virus. Furthermore, phylogenomic analysis was used to identify the lineage using the whole genome sequences of 44 LSDV isolates. The result revealed that the isolates from China were closely similar to that of the LSDV isolates from Vietnam, which are divided into a monophyletic lineage sub-group I. The SNPs and Simplot analysis indicate no significant occurrence of the recombinant event on the genome of LSDV isolates in China. Notably, the live virus challenge experiment demonstrated that the pathogenic characterization of this LSDV isolate belongs to a virulent strain. Collectively, we gain the first insight into the evolutionary trajectory, spatiotemporal transmission, and pathogenic characterization of circulating LSDV in China. This study provides a unique reference for risk assessment, guiding diagnostics, and prevention in epizootic and non-epizootic areas.

First complete genome sequence of lumpy skin disease virus directly from a clinical sample in South India

Lumpy skin disease (LSD), a notifiable disease listed by the World Organization for Animal Health and a fast fast-moving transboundary viral disease infecting cattle and buffaloes, was reported in India in 2019 and has since rapidly spread across the country. This study reports the first complete genome sequence and analysis of a pathogenic LSD virus (LSDV) from India (LSDV/208/PVNRTVU/2020) obtained by direct sequencing of a suspected clinical sample using Illumina and Nanopore sequencing technologies. The complete genome sequence of LSDV/208/PVNRTVU/2020 is 150445 bp long, codes for 156 putative genes and carries identical 2254 bp inverted terminal repeats at either ends. The unique features reported in the LSDV isolates from the recent outbreaks in Asia, namely, the insertions of 12 nucleotides in the viral G-protein coupled receptor (GPCR) and 27 nucleotides leading to duplication of 9 aminoacids in the extracellular enveloped virus-specific (EEV) genes were also conserved in LSDV/208/PVNRTVU/2020. Phylogenetic analysis of the complete genome sequence of LSDV/208/PVNRTVU/2020 revealed its close relation with Kenyan strains and clustered away from vaccine strains. Further analysis showed evidence of strong purifying selection without any recombination events. The data presented in this study could be useful for designing effective strategies such as developing rapid diagnostics and vaccines to control LSD.

Development and Validation of a New DIVA Real-Time PCR Allowing to Differentiate Wild-Type Lumpy Skin Disease Virus Strains, Including the Asian Recombinant Strains, from Neethling-Based Vaccine Strains

The current epidemic in Asia, driven by LSDV recombinants, poses difficulties to existing DIVA PCR tests, as these do not differentiate between homologous vaccine strains and the recombinant strains. We, therefore, developed and validated a new duplex real-time PCR capable of differentiating Neethling-based vaccine strains from classical and recombinant wild-type strains that are currently circulating in Asia. The DIVA potential of this new assay, seen in the in silico evaluation, was confirmed on samples from LSDV infected and vaccinated animals and on isolates of LSDV recombinants (n = 12), vaccine (n = 5), and classic wild-type strains (n = 6). No cross-reactivity or a-specificity with other capripox viruses was observed under field conditions in non-capripox viral stocks and negative animals. The high analytical sensitivity is translated into a high diagnostic specificity as more than 70 samples were all correctly detected with Ct values very similar to those of a published first-line pan capripox real-time PCR. Finally, the low inter- and intra-run variability observed shows that the new DIVA PCR is very robust which facilitates its implementation in the lab. All validation parameters that are mentioned above indicate the potential of the newly developed test as a promising diagnostic tool which could help to control the current LSDV epidemic in Asia.

Lumpy Skin Disease—An Emerging Cattle Disease in Europe and Asia

Lumpy skin disease virus (LSDV) is a member of the Capripoxvirus genus, mainly infecting cattle and buffalo, which until relatively recently was only endemic in parts of Africa and then spread to the Middle East and lately Europe and Asia. Lumpy skin disease (LSD) is a notifiable disease with a serious impact on the beef industry as it causes mortality of up to 10% and has impacts on milk and meat production, as well as fertility. The close serological relationship between LSDV, goat poxvirus (GTPV) and sheep poxvirus (SPPV) has led to live attenuated GTPV and SPPV vaccines being used to protect against LSD in some countries. There is evidence that the SPPV vaccine does not protect from LSD as well as the GTPV and LSDV vaccines. One of the LSD vaccines used in Eastern Europe was found to be a combination of different Capripoxviruses, and a series of recombination events in the manufacturing process resulted in cattle being vaccinated with a range of recombinant LSDVs resulting in virulent LSDV which spread throughout Asia. It is likely that LSD will become endemic throughout Asia as it will be very challenging to control the spread of the virus without widespread vaccination.

Genomic characterization of Lumpy Skin Disease virus (LSDV) from India: Circulation of Kenyan-like LSDV strains with unique kelch-like proteins

Lumpy skin disease (LSD) is an economically important poxviral disease endemic to Asia, Europe, and Africa. Recently, LSD has spread to naïve countries, including India, China, Bangladesh, Pakistan, Myanmar, Vietnam, and Thailand. Here, we describe the complete genomic characterization of LSDV from India, LSDV-WB/IND/19 isolated from an LSD affected calf in 2019 determined by Illumina next-generation sequencing (NGS). The LSDV-WB/IND/19 has a genome size of 150,969 bp encoding 156 putative ORFs. Phylogenetic analysis based on complete genome sequence suggested that LSDV-WB/IND/19 is closely related to Kenyan LSDV strains with 10-12 variants with non-synonymous changes confined to LSD_019, LSD_049, LSD_089, LSD_094, LSD_096, LSD_140, and LSD_144 genes. In contrast to complete kelch-like proteins in Kenyan LSDV strains, LSDV-WB/IND/19 LSD_019 and LSD_144 genes were found to encode truncated versions (019a, 019b, and 144a, 144b). LSD_019a and LSD_019b proteins of LSDV-WB/IND/19 resemble that of wild-type LSDV strains based on SNPs and the C-terminal part of LSD_019b except for deletion at K229, whereas the LSD_144a and LSD_144b proteins resemble that of Kenyan LSDV strains based on SNPs, however, C-terminal part of LSD_144a resembles that of vaccine-associated LSDV strains due to premature truncation. The NGS findings were confirmed by Sanger sequencing of these genes in Vero cell isolate as well as in the original skin scab along with similar findings in another Indian LSDV from scab specimen. LSD_019 and LSD_144 genes are thought to modulate virulence and host range in capripoxviruses. This study demonstrates the circulation of unique LSDV strains in India and highlights the importance of constant monitoring of the molecular evolution of LSDV and associated factors in the region in light of the emergence of recombinant LSDV strains.

The Characterization and Differentiation of Recombinant Lumpy Skin Disease Isolates Using a Region within ORF134

The recent description and characterization of several novel and unique lumpy skin disease virus (LSDV) strains have revealed the inadequacy of current techniques for differentiating between vaccine- and wild-type viruses. The lack of reliable sequencing targets for promptly distinguishing circulating recombinant vaccine-like strains (RVLSs) highlights the need to develop a single and simple differentiation tool. In this study, we analyzed the available LSDV whole-genome sequences and identified a 705-bp region in open reading frame (ORF) LW134. Based on a single run of nucleotide sequencing and phylogenetic analysis, the region with 13 informative single nucleotide polymorphisms (SNPs) was capable of accurately segregating the novel RVLSs into the same five clusters previously confirmed by whole-genome sequencing. In addition, archived RVLSs from Russia were analyzed for further characterization using the newly described single PCR and sequencing assay. The ORF LW134 assay identified one archived RVLS as a novel cluster distinct from the previously described five clusters, while clustering the remaining samples into previously designated lineages, demonstrating the reliability of the assay. The novel PCR and sequencing assays described in this study have great potential for accurately delineating the molecular and evolutionary affiliation of circulating RVLSs.

Understanding the research advances on lumpy skin disease: A comprehensive literature review of experimental evidence

Lumpy skin disease is caused by lumpy skin disease virus (LSDV), which can induce cattle with high fever and extensive nodules on the mucosa or the scarfskin, seriously influencing the cattle industry development and international import and export trade. Since 2013, the disease has spread rapidly and widely throughout the Russia and Asia. In the past few decades, progress has been made in the study of LSDV. It is mainly transmitted by blood-sucking insects, and various modes of transmission with distinct seasonality. Figuring out how the virus spreads will help eradicate LSDV at its source. In the event of an outbreak, selecting the most effective vaccine to block and eliminate the threat posed by LSDV in a timely manner is the main choice for farmers and authorities. At present, a variety of vaccines for LSDV have been developed. The available vaccine products vary in quality, protection rate, safety and side effects. Early detection of LSDV can help reduce the cost of disease. In addition, because LSDV has a huge genome, it is currently also used as a vaccine carrier, forming a new complex with other viral genes through homologous recombination. The vaccine prepared based on this can have a certain preventive effect on many kinds of diseases. Clinical detection of disease including nucleic acid and antigen level. Each method varies in convenience, accuracy, cost, time and complexity of equipment. This article reviews our current understanding of the mode of transmission of LSDV and advances in vaccine types and detection methods, providing a background for further research into various aspects of LSDV in the future.

Lumpy Skin Disease: An Economically Significant Emerging Disease

Lumpy skin disease (LSD) is a severe viral disease of cattle caused by the lumpy skin disease virus (LSDV), a member of the Capripoxvirus genus of the poxviridae family. Fever and flat disk-like skin nodules on the skin characterize the disease. It can also lead to death and significant economic losses, especially in herds, that have never been exposed to the virus. Blood-feeding insects, such as specific types of flies, mosquitoes, and ticks, are thought to be the primary vectors of LSDV transmission. Most African and middle eastern countries have a high prevalence of lumpy skin disease. The disease extended to southeast Europe, the Balkans, and the Caucasus in 2015 and 2016 and is still spreading throughout Asia. The World Organization for Animal Health [WOAH] has designated LSD as a notifiable illness due to the likelihood of fast transmission. The rapid spread of disease in formerly disease-free areas emphasizes the need to know the disease epidemiology and the virus’s interaction with its host. This chapter aims to provide the latest developments in the etiology, epidemiology, diagnosis, and control of LSD.

Genetic characterization of sheep pox virus strains from outbreaks in Central Russia in 2018-2019

This study investigates the phylogenomic relatedness between sheep pox viruses (SPPVs) circulating in Central Russia in 2018-2019 with the NISKHI vaccine strain used in the country, based on their complete genome sequences. The sheep pox outbreaks occurred 1 year apart in the adjacent regions of Tula and Moscow. Full genome sequences were generated by sequencing DNA directly obtained from Trizol-extracted scabs, using the DNBSEQ-400 platform (MGI Tech, China). Phylogenetic analysis indicated that the SPPV isolates from Russia clusters with previously published sequences from Srinagar in the Kashmir province of India in 2000 (SPPV-Srinagar strain) as well as SPPV A strain from Kazakhstan in 2000. The aforementioned cluster belonged to a sister clade containing the NISKHI vaccine strain, thus indicating that the recent outbreaks were not genetically linked to the widely used vaccine.

Experimentally controlled study indicates that the naturally occurring recombinant vaccine-like lumpy skin disease strain Udmurtiya/2019, detected during freezing winter in northern latitudes, is transmitted via indirect contact

Lumpy skin disease (LSD) caused by LSD virus (LSDV), is a member of the poxvirus genus Capripoxvirus. It is classified as a notifiable disease by the World Organization for Animal Health (WOAH) based on its potential for rapid spread and global economic impact. Due to these characteristics, the mode of LSDV transmission has prompted intensive research efforts. Previous experimental studies using the virulent vaccine-derived recombinant LSDV strain Saratov/2017, demonstrated that this strain has the capacity for transmission in a vector-proof environment. This study demonstrated that a second novel recombinant vaccine-derived LSDV strain Udmurtiya/2019, can infect bulls in contact with diseased animals, in the absence of insect vectors. Bulls were housed in an insect proof animal biosafety level 3 facility, where half the animals were inoculated intravenously with the recombinant LSDV (Udmurtiya/2019), whilst the remaining five animals were mock-inoculated but kept in contact with the inoculated group. Both the infected / inoculated group (IN) and uninfected / incontact group (IC), were monitored for 41 days with continuous registration of body temperature, observations for clinical signs and collection of blood samples and nasal swabs for testing of LSDV presence using real-time PCR. Results indicated that cohabitation of animals from both groups was sufficient to transmit the virus from the IN to the IC-group, with the onset of clinical signs including pyrexia (~41°C) and classical LSD nodular skin lesions starting at 10 dpi for the IN group and 16 dpi for the IC-group. Additionally, the presence of LSDV genomes as well as anti-LSDV antibodies were detected in swabs, blood and serum samples from animals belonging to both groups. These results provides additional evidence of LSDV transmission in a controlled environment without direct contact between diseased and healthy animals, yet in the absence of vectors. Based on these observations, the question concerning a hypothetical relation between mutations in the virus genome and its mode of transmission gains more importance and requires additional investigations with direct comparisons between classical and novel recombinant LSDV strains.

Capripoxviruses, leporipoxviruses, and orthopoxviruses: Occurrences of recombination

Poxviruses are double-stranded DNA viruses with several members displaying restricted host ranges. They are genetically stable with low nucleotide mutation rates compared to other viruses, due to the poxviral high-fidelity DNA polymerase. Despite the low accumulation of mutations per replication cycle, poxvirus genomes can recombine with each other to generate genetically rearranged viruses through recombination, a process directly associated with replication and the aforementioned DNA polymerase. Orthopoxvirus replication is intimately tethered to high frequencies of homologous recombination between co-infecting viruses, duplicated sequences of the same virus, and plasmid DNA transfected into poxvirus-infected cells. Unfortunately, the effect of these genomic alterations on the cellular context for all poxviruses across the family Poxviridae remains elusive. However, emerging sequence data on currently circulating and archived poxviruses, such as the genera orthopoxviruses and capripoxviruses, display a wide degree of divergence. This genetic variability cannot be explained by clonality or genetic drift alone, but are probably a result of significant genomic alterations, such as homologous recombination, gene loss and gain, or gene duplications as the major selection forces acting on viral progeny. The objective of this review is to cross-sectionally overview the currently available findings on natural and laboratory observations of recombination in orthopoxviruses, capripoxviruses, and leporipoxviruses, as well as the possible mechanisms involved. Overall, the reviewed available evidence allows us to conclude that the current state of knowledge is limited in terms of the relevance of genetic variations across even a genus of poxviruses as well as fundamental features governing and precipitating intrinsic gene flow and recombination events.

Development of gold nanoparticles-lateral flow test as a novel field diagnostic assay for detecting foot-and-mouth disease and lumpy skin disease viruses

Background and Objectives

Rapid diagnosis is a cornerstone for controlling and preventing viral disease outbreaks. The present study is aimed to develop a rapid field diagnostic test based on gold nanoparticles for the detection of lumpy skin diseases (LSD), and foot and mouth diseases (FMD) in animals with high sensitivity and specificity.

Materials and Methods

FMD and LSD vaccines were used as a source of viruses' antigens for preparing monoclonal antibodies and conjugated with gold nanoparticles that characterized using various techniques such as UV-visible spectrometry, and transmission electron microscopy (TEM). Monoclonal antibodies (mAbs) for each serotype produced in experimental rats and used to capture antibodies for FMDV and/or LSDV. ELISA was used to screen 469 milk samples and 1165 serum samples from naturally infected cattle, buffaloes, sheep, and goats for validation of the lateral flow test (LFT). LSDV DNA was extracted from 117 blood and skin biopsy samples collected from naturally infected cattle during the 2019 outbreak.

Results

The specificity and sensitivity of GNP-LFT were evaluated and compared to Ag-ELISA, Western blot tests (WB), and PCR. A total of 95 FMDV positives out of 469 (20.25%) milk samples and 268 FMDV positives out of 1165 (23.3%) serum samples from natural infected cattle, buffaloes, sheep, and goats examined by ELISA to valid GNPS-LFT Viral LSDV DNA was detected in 60/117 (51.5%) and 31/60 (52.9%). While the GNPS-LFT assay results were 49/117 (41.9%) and 29/60 (48.3%) blood and skin biopsy samples, respectively. The diagnostic sensitivity and specificity of the GNP-LFT test were 72% and 82%, respectively. All vesicular fluid and epithelium samples collected from infected animals were identified as positive by the GNP-LFT and Ag-ELISA. Ag-ELISA, on the other hand, was 90% and 100%. While the developed GNP-LFT used LSDV polyclonal antibodies were similar to ELISA and IgG-WB with a sensitivity of 72.8% and a specificity of 88.8%, respectively.

Conclusion

The GNPS-LFT is a novel immunoassay based on mono or polyclonal antibodies conjugated with gold nanoparticles that provides an accurate, rapid, specific, and sensitive tool for field rapid diagnosis of FMDV and LSDV.