Clinical study and the diagnosis of lumpy skin disease in cattle using genomic, immunological, and pathological indicators.

Abstract

INTRODUCTION: Lumpy skin disease (LSD) is a transboundary animal disease that has serious implications for livestock trade and food security. This study aimed to investigate the molecular and immunological determinants of LSD in vaccinated cattle that developed clinical disease (vaccine breakthrough cases), and to identify potential biomarkers to support disease surveillance and control strategies. METHODS: Blood samples were collected from 50 clinically healthy cattle (controls) and 50 vaccinated cattle with clinical signs of LSD. Each blood sample was divided into two portions: EDTA-treated blood was used for viral DNA and total RNA extraction for assessing gene expression of immune and antioxidant genes, PCR amplification, partial sequencing, and phylogenetic analysis of the ORF95 gene, whereas serum samples were used to evaluate biochemical, antioxidant, and immunological parameters. In addition, 2-3 skin nodules were surgically excised from the affected animals for pathological examination. Gene expression and sequencing analyses of TLR7, TLR8, TLR9, SOD3, CAT, and GPX were performed in both groups, and single nucleotide polymorphisms (SNPs) were detected. RESULTS AND DISCUSSION: Clinically affected cattle exhibit pyrexia (40-41 &#xb0;C) and characteristic nodular skin lesions. Partial ORF95 sequences obtained from infected cattle clustered closely with the circulating field strains, indicating active field virus circulation despite vaccination. Histopathological examination revealed typical lesions including epidermal necrosis with eosinophilic intracytoplasmic inclusions, dermal ulceration, and fibrinous exudation. Serum analyses demonstrated significant alterations in inflammatory cytokine levels, oxidative stress indices, and metabolic parameters, consistent with systemic inflammation and oxidative imbalance. Molecular analyses showed significant upregulation of toll-like receptor 7 (TLR7), toll-like recep tor 8 (TLR8), and toll-like receptor 9 (TLR9), accompanied by the downregulation of antioxidant genes; superoxide dismutase 3 (SOD3), catalase (CAT), and glutathione peroxidase (GPX) in infected cattle (< 0.05). Five SNPs were identified in the investigated genes in the affected animals. Overall, these findings indicate a pronounced inflammatory and oxidative stress response in LSDV-infected cattle, and suggest the involvement of specific genetic variants that may contribute to disease susceptibility.