Emergency vaccination of cattle against lumpy skin disease: Evaluation of safety, efficacy, and potency of MEVAC® LSD vaccine containing Neethling strain

Molecular detection of lumpy skin disease virus in naturally infected cattle and buffaloes: unveiling the role of tick vectors in disease spread

Lumpy skin disease (LSD) is a viral disease that affects cattle and buffaloes in Egypt, causing considerable economic losses in the animal sector. This study aimed to investigate the recent outbreak of LSDV in cattle and buffaloes and evaluate the potential role of the hard tick Rhipicephalus annulatus in their transmission through isolation and molecular characterization by multiplex PCR (mPCR) and real-time quantitative PCR (rt-qPCR) assays. A total of 50 skin biopsies (cattle n = 30, buffaloes n = 20), 110 nasal swabs (cattle n = 76, buffaloes n = 44), and 129 blood samples (cattle n = 84, buffaloes n = 45) were collected. In addition, 145 hard ticks of different stages were collected from cattle and buffaloes of different breeds and ages in different governorates in Egypt from November 2021 to June 2022. Multiplex PCR and real-time quantitative PCR (rt-qPCR) assays based on SYBR Green and targets (P32, VP32, G protein, and viral fusion protein) were used. We identified positive results in 17 out of 30 cattle skin biopsies (56.6%), 1 out of 7 buffalo skin scabs (14.3%), and 5 out of 45 buffalo blood samples (11.11%) using mPCR and RT-qPCR methods. We successfully isolated LSDV from hard ticks and cattle infested with ticks and exhibited characteristic signs of LSD on the chorioallantois membrane (CAM) of specific pathogen-free embryonated chicken eggs (SPF-ECE). The isolates were confirmed by multiplex PCR and RT-qPCR. The cyclic threshold (Ct) with correlation-slandered curve values of rt-qPCR ranging from 10.2 to 36.5 showed the amount of LSDV-DNA in different samples. The study's findings demonstrated the widespread circulation of LSDV in both cattle and buffaloes in Egypt and provided strong evidence that hard ticks R. annulatus play a role in the transmission of LSDV in susceptible animals.

The Current Epizootiological Situation of Three Major Viral Infections Affecting Cattle in Egypt

One of the major factors hindering efficient livestock production is the presence of high-impact infectious animal diseases, such as foot and mouth disease (FMD), lumpy skin disease (LSD), and bovine ephemeral fever (BEF), which are notable viral infections affecting cattle in Egypt, leading to significant economic losses. FMD is caused by the foot and mouth disease virus (FMDV) of the genus Aphthovirus in the Picornaviridae family. LSD is caused by lumpy skin disease virus (LSDV) of Capripox genus within the Poxviridae family, subfamily Chordopoxvirinae. BEF is caused by bovine ephemeral fever virus (BEFV) of genus Ephemerovirus in the Rhabdoviridae family. FMD is a highly contagious viral infection of domestic and wild cloven-hooved animals and can spread through the wind. On the other hand, LSD and BEF are arthropod-borne viral diseases that mainly affect domestic cattle and water buffalo. Despite government vaccination efforts, these three viral diseases have become widespread in Egypt, with several reported epidemics. Egypt's importation of large numbers of animals from different countries, combined with unregulated animal movements through trading and borders between African countries and Egypt, facilitates the introduction of new FMDV serotypes and lineages not covered by the current vaccination plans. To establish an effective control program, countries need to assess the real epizootic situation of various infectious animal diseases to develop an efficient early warning system. This review provides information about FMD, LSD, and BEF, including their economic impacts, causative viruses, global burden, the situation in Egypt, and the challenges in controlling these diseases.

Potential Inhibitors of Lumpy Skin Disease's Viral Protein (DNA Polymerase): A Combination of Bioinformatics Approaches

Lumpy skin disease (LSD), caused by a virus within the Poxviridae family and Capripoxvirus genus, induces nodular skin lesions in cattle. This spreads through direct contact and insect vectors, significantly affecting global cattle farming. Despite the availability of vaccines, their efficacy is limited by poor prophylaxis and adverse effects. Our study aimed to identify the potential inhibitors targeting the LSDV-encoded DNA polymerase protein (gene LSDV039) for further investigation through comprehensive analysis and computational methods. Virtual screening revealed rhein and taxifolin as being potent binders among 380 phytocompounds, with respective affinities of -8.97 and -7.20 kcal/mol. Canagliflozin and tepotinib exhibited strong affinities (-9.86 and -8.86 kcal/mol) among 718 FDA-approved antiviral drugs. Simulating the molecular dynamics of canagliflozin, tepotinib, rhein, and taxifolin highlighted taxifolin's superior stability and binding energy. Rhein displayed compactness in RMSD and RMSF, but fluctuated in Rg and SASA, while canagliflozin demonstrated stability compared to tepotinib. This study highlights the promising potential of using repurposed drugs and phytocompounds as potential LSD therapeutics. However, extensive validation through in vitro and in vivo testing and clinical trials is crucial for their practical application.

The impact of mass vaccination policy and control measures on lumpy skin disease cases in Thailand: insights from a Bayesian structural time series analysis

Introduction

In 2021, Thailand reported the highest incidence of lumpy skin disease (LSD) outbreaks in Asia. In response to the widespread outbreaks in cattle herds, the government's livestock authorities initiated comprehensive intervention measures, encompassing control strategies and a national vaccination program. Yet, the efficacy of these interventions remained unevaluated. This research sought to assess the nationwide intervention's impact on the incidence of new LSD cases through causal impact analysis.

Methods

Data on weekly new LSD cases in Thailand from March to September 2021 was analyzed. The Bayesian structural time series (BSTS) analysis was employed to evaluate the causal relationship between new LSD cases in the pre-intervention phase (prior to the vaccination campaign) and the post-intervention phase (following the vaccination campaign). The assessment involved two distinct scenarios, each determined by the estimated effective intervention dates. In both scenarios, a consistent decline in new LSD cases was observed after the mass vaccination initiative, while other control measures such as the restriction of animal movement, insect control, and the enhancement of the active surveillance approach remained operational throughout the pre-intervention and the post-intervention phases.

Results and discussion

According to the relative effect results obtained from scenario A and B, it was observed that the incidence of LSD cases exhibited reductions of 119% (95% Credible interval [CrI]: -121%, -38%) and 78% (95% CrI: -126, -41%), respectively. The BSTS results underscored the significant influence of these interventions, with a Bayesian one-sided tail-area probability of p < 0.05. This model-based study provides insight into the application of BSTS in evaluating the impact of nationwide LSD vaccination based on the national-level data. The present study is groundbreaking in two respects: it is the first study to quantify the causal effects of a mass vaccination intervention on the LSD outbreak in Thailand, and it stands as the only endeavor of its kind in the Asian context. The insights collected from this study hold potential value for policymakers in Thailand and other countries at risk of LSD outbreaks.

Complete Genomic Characterization of Lumpy Skin Disease Virus Isolates from Beef Cattle in Lopburi Province, Central Thailand, during 2021-2022

Lumpy skin disease (LSD) is a viral infection that impacts the cattle industry. The most efficient approach to prevent disease involves the utilization of live-attenuated LSD vaccines (LAVs), which stands out as the most successful method. However, LAVs might be subjected to changes to their genomes during replication that increase viral infectivity or virulence. The objective of this study was to monitor alterations in the genetic characteristics of the lumpy skin disease virus (LSDV) in beef cattle following the administration of LAVs in Lopburi Province of Central Thailand. A total of four skin samples from LSD cases were collected from non-vaccinated animals that exhibited LSD clinical symptoms from two distinct districts, spanning three subdistricts within the region. The samples of cattle were analyzed using real-time PCR targeting the LSDV074 p32 gene, the virus was isolated, and the entire genome sequences were evaluated through a single nucleotide polymorphisms (SNPs) analysis, and phylogenetic trees were assembled. The investigations revealed that LSDVs from two isolates from Chai Badan district exhibited significant mutations in the open reading frame (ORF) 023 putative protein, while another two isolates from Lam Sonthi district had a change in the untranslated region (UTR). For a result, the most proficient disease diagnosis and control should be evaluated on viral genetics on a regular basis.