Lumpy skin disease outbreaks investigation in Egyptian cattle and buffaloes: Serological evidence and molecular characterization of genome termini.

ABSTRACT

Lumpy skin disease (LSD) is an endemic highly infectious viral disease affecting cattle in Egypt. This study aimed to identify and characterize the LSD virus (LSDV) outbreaks in Egypt between 2016 and 2018 and to determine the role of Egyptian buffaloes in the epidemiology of LSD. A total of 44 skin biopsies (41 from cattle and 3 from buffaloes) and 31 blood samples from asymptomatic buffaloes in contact with clinically infected cattle were collected from 7 Egyptian governorates and tested by real-time (rt)-PCR. The positive samples were further isolated, and the isolates were analyzed by conventional PCR to amplify the LSDV001 and LSDV002 genes; three isolates were sequenced, and the phylogenetic tree was constructed. In addition, 198 serum samples (102 from cattle and 96 from contact buffaloes) were examined using ELISA. Out of 44 skin nodules analyzed by rt-PCR, 31 (70.45 %) were positive while, non of the buffalo samples were positive. Out of 31 positive rt-PCR samples, LSDV was isolated on CAM (n=19; 61.29%) and MDBK cell culture. The virus isolates were confirmed by conventional PCR where 1237 bp product size was successfully amplified. The phylogenetic analysis of LSDV002 gene revealed that three sequenced LSDV isolates were identical to each other and to LSDV isolates from different countries in Africa, Asia, and Europe with 99-100 % identity. ELISA analyses showed seroreactivity of LSDV in Egyptian cattle and buffaloes. In conclusion, the Egyptian water buffalo serves as an accidental non-adapted host for the disease and this point requires more deep investigation. In addition, the current vaccine strategy should be re-evaluated for more coverage and effectiveness.