الفهرس 
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Abstract
Lumpy skin disease (LSD) is one of the most economically significant emerging and transboundary diseases of cattle. Several outbreaks were recorded in different Egyptian provinces during the last three years (2016-2018). This study aimed to isolate and molecularly characterize LSDV in cattle and buffaloes in Egypt during 2015-2018.
Forty-four biopsy samples were collected for virus isolation on chorio-allantoic membrane (CAM) and MDBK cell lines, molecular identification by conventional and real-time PCR. 31 out of 44 samples were positive by probe-based real-time PCR displaying different CT values with percentage 70.5%. Conventional PCR used in this study was able to differentiate between LSDV and other Capri poxviruses (CaPVs) by targeting LSDV132 and TK gene . the comparison between both probe-based real-time and conventional PCR revealed 78.95% sensitivity, 100% specificity, and 80.95 % Accuracy, in this comparison only 26.66% (n=4 samples from n=15 known positive) were
negative and 73.33% (11 samples from 15 known positive) showed positive results by proper amplification of target sequence after analysis using gel PCR. LSDV was also isolated on the CAM of ECE then further propagation of isolates using MDBK culture cells that displayed characteristic CPE for LSDV in 19 samples out of 31. Positive samples that showed CPE on CAM and MDBK cell culture were selected to be confirmed by conventional PCR using pair of specific LSDV primers and the 1237 bp expected product size was successfully amplified.
Sequencing isolates were done for three isolates from GIZA, Fayoum and Menufyia provinces and the phylogenetic tree constructed to prove these three isolates are similar to each other with identity percent ranged from 99.3% to 100%. The nucleotides and amino acids alignment for LSDV002 fragment which is specific to LSDV proved full identity of the three isolates compared with LSDV sequences previously submitted to gene bank from Egypt as Ismailia LSDV002 complete gene and LSDV isolate Egypt-BSU/Damietta-1/2012 hypothetical protein (LSDV002) gene that isolated from Egypt (2012).
The immune response in infected animals was investigated using the ELISA test where single and paired serum samples were collected from clinical infected cases, in the first 3 days all sample were negative and after 2-3 weeks were positive. All samples collected as a single sample after 2-4 weeks were positive (100%).
Buffaloes contacted with infected Cows with LSDV were tested using a probe-based real-time PCR on blood samples and all samples proved to be negative. Serological investigation of LSDV in buffaloes using ELISA proved mild response to LSDV where out of 65 samples only 12 (13.8 %) samples were positive in Ismailia province and out of 31 samples there only 5(16%) positive give the final percentage of (17.7%) from total buffaloes tested serum samples (n=96) this result proved the mild seropositive buffaloes however they were in contact with infected cattle that suggest the Buffaloes may be accidental non-adaptive host.