Staphylococcus aureus is among the most frequent causes of bovine mastitis worldwide. The strains associated with mastitis belong to bovine adapted lineages, with each lineage encoding a diverse assemblage of regulators and effectors of virulence, which could influence disease presentation and outcome. To investigate the influence of bacterial strain and lineage on the host immune response, 12 bovine adapted S. aureus strains, 3 from each of the lineages CC71, CC97, ST136, and CC151, were characterized for their ability to induce a pro-inflammatory immune response from mammary epithelial cells (MEC) and stimulate neutrophil chemotaxis, their propensity to invade MEC and their survival during incubation with granulocytes. Strains from lineage CC97 were strongly pro-inflammatory and induced MEC to produce chemotactic factors that attracted neutrophils. In contrast, strains from CC151 only weakly induced the expression of pro-inflammatory cytokines and did not induce expression of chemotactic factors. There were no differences between strains in ability to survive neutrophil killing while strains belonging to ST136 poorly internalised into MEC. One strain each of CC151 and CC97 were selected for in vivo studies. Healthy first-lactation Holstein-Friesian heifers were infected, 7 with a CC97 strain (Group 1) and 7 with a CC151 strain (Group 2). Clinical signs of infection were monitored for 30 d. Differences in disease presentation between groups were observed, with 2 animals from Group 2 developing clinical mastitis and requiring antibiotic treatment, while one animal from Group 1 did not develop an infection for the duration of the study. Fever was observed in 3 animals from Group 2 and in none from Group 1. Significant differences in SCC and bacterial load between groups were also observed. The results of this study suggest that strains from lineage CC151 may fail to elicit an early immune response allowing them to establish and cause more severe mastitis than strains from lineage CC97. Diversity between strains of S. aureus may therefore influence the clinical presentation of mastitis, disease detection and treatment needs.