Replication and Virulence in Cattle of the First Lumpy Skin Disease Virus Isolated in Xinjiang, China (2019)

Before 2012, lumpy skin disease (LSD) was primarily confined to African countries. However, it rapidly spread to the Middle East and Southeast Europe, reaching the Balkans, the Caucasus, and the Russian Federation by 2015. The first confirmed case in China was reported on August 10, 2019, in Yili, Xinjiang, and on August 26, the Chinese government officially notified the World Organization for Animal Health (WOAH) of the outbreak. In this study, we isolated a LSD virus (LSDV) strain from a severely affected cattle skin sample collected in the Yili region of Xinjiang and designated it as strain Xinjiang/2019. Next-generation sequencing (NGS) analysis revealed that strain Xinjiang/2019 shared the highest similarity with the LSDV/Russia/Saratov/2017 strain based on full-length LSDV sequences available in NCBI. Phylogenetic analysis revealed that the Xinjiang/2019 isolate clustered with strains from China, Vietnam, Thailand, and Indonesia, forming a distinct phylogenetic branch. Recombination analysis further indicated that Xinjiang/2019 is predominantly a recombinant strain, derived from South African and European strains. To assess pathogenicity, cattle were infected with strain Xinjiang/2019 via intravenous (Group I) or intradermal (Group II) injection. In Group I, four out of five animals developed typical LSD symptoms, including fever (day 7), secondary nodules (day 8), rhinitis, conjunctivitis, and lymph node enlargement. Group II showed viremia by day 5 with milder symptoms. These findings indicate that strain Xinjiang/2019 is a virulent strain responsible for the first LSD outbreak in China.