AUTHOR=Liu Kai , Deng Zhaoju , Zhang Limei , Gu Xiaolong , Liu Gang , Liu Yang , Chen Peng , Gao Jian , Han Bo , Qu Weijie 

TITLE=Biological Characteristics and Pathogenicity of Helcococcus ovis Isolated From Clinical Bovine Mastitis in a Chinese Dairy Herd

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.756438

DOI=10.3389/fvets.2021.756438

ISSN=2297-1769

ABSTRACT=<p><italic>Helcococcus ovis</italic> (<italic>H. ovis</italic>) was first reported in ovine subclinical mastitis milk and post-mortem examination organs in Spain and the United Kingdom in 1999; subsequently, it appeared in cattle, horse, goat, and human. However, isolation and characterization of the pathogen from clinical bovine mastitis is unknown. The objective of this study was to identify the pathogen in clinical bovine mastitis. A total of four strains were isolated from bovine mastitis milk samples from a Chinese dairy farm, and they were identified as <italic>H. ovis</italic> by microscopic examination and 16S rRNA gene sequencing. Phylogenetic tree was constructed using 16S rRNA gene, and the isolates were closely related to other China strains and strains from Japan. The growth speed of the <italic>H. ovis</italic> isolated was relatively slower than <italic>Streptococcus agalactiae</italic>, and the phenotypic characteristics were similar to <italic>H. ovis</italic> CCUG37441 and CCUG39041 except to lactose. The isolates were sensitive to most of the common used antimicrobials. The <italic>H. ovis</italic> isolates could lead to mild murine mastitis alone and induce severe mastitis when co-infected with <italic>Trueperella pyogenes</italic> in the murine mammary infection model constructed.</p>