Molecular Detection of Lumpy Skin Disease Virus in Naturally Infected Cattle and Buffaloes: Unveiling the Role of Tick Vectors in Disease Spread

Abstract

Lumpy Skin Disease (LSD) is a recently pervasive viral infection affecting cattle and buffaloes in Egypt, causing considerable economic losses in the animal sector. The aim of this study is to detect the potential impact role of hard ticks, Rhipicephalus annulets (R. boophilus annulets), in the spreading of Lumpy Skin Disease Virus (LSDV), with the characterization of isolates through molecular analysis. A total of 50 skin biopsies, 110 nasal swabs, and 129 blood samples were collected from cattle of different breeds and ages across different governorates in Egypt from November 2021 to June 2022. Additionally, 145 hard ticks of R. boophilus annulatus from different stages were collected. Multiplex PCR and real-time quantitative PCR (rt-qPCR) assays using SYBR Green were targets (P32, VP32, G protein, and viral fusion protein). They detected LSDV in 17 out of 30 cattle skin biopsies 56.6%), 1 out of 7 buffalo biopsies (14.3%), and only 5 blood samples from buffaloes (11.11%). Buffaloes appeared to be less susceptible to the virus than cattle; they may act as accidental hosts. We successfully isolated the virus from hard ticks and cattle exhibiting LSD clinical signs and harboring ticks in the chorioallantois membrane (CAM) route of specific pathogen-free, embryonated chicken eggs (SPF-ECE) and confirmed the isolates by multiplex PCR and rt-qPCR. Ct values ranging from 10 to 36.5 showed the amount of LSDV-DNA in different samples. The study's findings demonstrate the widespread circulation of LSDV in both cattle and buffaloes in Egypt and provide strong evidence that hard ticks (R. annulatus) ticks play a role in LSDV transmission in susceptible animals.