Demonstration of the pathogenicity of LSDV pendik strain in cattle.

Lumpy Skin Disease Virus (LSDV) remains a significant threat to cattle health and productivity. This study investigated the pathogenesis of the LSDV Pendik field strain in cattle to assess its suitability as a challenge virus for LSD vaccine efficacy trials. Two calves aged between six and nine months were inoculated intravenously, and four were inoculated intradermally with the virus. Clinical signs were monitored for 28 days, and blood, nasal, and conjunctival swab samples were collected at predetermined intervals to detect viral DNA by real-time PCR. Positive tissue samples obtained at necropsy were subjected to virus isolation using the bovine dermis (LB9.D) cell line. Among the intravenously inoculated calves, one developed subclinical infection while the other exhibited generalized disease. Of the intradermally inoculated animals, two developed generalized lesions and two showed localized skin lesions. Fever occurred between 3- and 23-days post-inoculation, and viral DNA was detected in blood samples from three animals between 7 and 21 dpi. Nasal and conjunctival shedding was confirmed in all infected cattle, being most prominent on day 19. Viral DNA was detected in the skin, lung, liver, heart, spleen, rumen, kidney, testis, and hair root, and the virus was successfully isolated from the skin, hair root, heart, lung, rumen, kidney, and nasal swabs. Two animals were humanely euthanized during the study due to severe clinical progression. These findings demonstrate that the LSDV Pendik strain is pathogenic in cattle and is suitable for use as a standardized challenge strain in LSD vaccine efficacy evaluations.