Differential gene expression in dromedary camels infested with sarcoptic mange

Abstract

Sarcoptic mange is one of the most common parasitic diseases in camels, caused by Sarcoptes scabiei var. cameli. Affected animals suffer production losses, and young animals may even die. Although the disease is highly contagious, some animals remain healthy despite being in the same environment as infected ones. The severity of infection also varies among individuals. However, a comprehensive genome-wide study to identify defence-related genes associated with mange resistance in camels has not yet been undertaken. Therefore, the present study was designed to investigate differential gene expression, single nucleotide polymorphisms (SNPs), and insertions/deletions (Indels) associated with natural resistance to Sarcoptes scabiei var. cameli infection in dromedary camels. Skin scrapings were collected from both infected animals and healthy animals within the same herd. RNA isolation and transcriptome analysis were conducted. The parasite-unaligned sequences were further analysed for SNPs, Indels, gene expression quantification, and differential expression. In total, 23,008 genes were analysed. Results showed that gene expression was relatively lower in the infected group (84.94%) compared to the healthy group (87.28%). The number of SNPs/Indels in exonic regions was higher in the infected group (5,538) compared to the healthy group (3,629). Among the upregulated genes, several were associated with inflammatory responses, adipogenesis, fibroblast growth, immune responses, inhibition of TNF-α and C-reactive protein, suppression of high glucose-induced NF-κB activity, apoptosis, autoimmunity, lipid metabolism, adipose lipolysis, blood clotting, cell movement, and tissue remodelling. Downregulated genes in infected animals were involved in processes such as cell cycle progression, locomotion in vertebrates, formation of a rigid and resistant hair shaft, conversion of upstream fatty acids into polyunsaturated fatty acids (PUFAs), renal function and hypertension biomarkers, wool and hair fibre formation, various cellular activities, renal cyst formation, congenital hepatic fibrosis, and immune responses. Further, several differentially expressed genes (DEGs), such as CXCL8, IDO1, IGFBP3, and KRTAP6-2, emerge as promising biomarkers for diagnosis, prognosis, and therapeutic targeting. These findings establish a transcriptomic foundation for future investigations and open avenues for developing molecular tools to improve disease management strategies in camels.

Keywords: Camel; Differential expression; Genes; Mange.