In addition, S. aureus produce a variety of secreted proteins involved in immune evasion or modulation, often targeting complement and neutrophil recruitment [10–12]. S. aureus Seliciclib molecular weight populations consist of dominant lineages with some minor lineages. Multi- strain whole genome S. aureus microarray studies have shown that each S. aureus lineage is highly distinct, and that each lineage possesses a unique combination

of conserved surface proteins and their regulators [13]. Difference also exists in the expression and secretion of S. aureus proteins [14]. The major human lineages are clonal complex (CC)1, CC5, CC8, CC9, CC12, CC15, CC22, CC25, CC30, CC45 and CC51 [15]. The lineages that have acquired mecA to become widespread selleck kinase inhibitor hospital acquired (HA-)MRSA are CC5, CC8, CC22, CC30, CC45 and a hybrid lineage CC239 [16, 17]. The lineages that have acquired mecA to become widespread community associated (CA-)MRSA are CC1, CC8, CC30, CC59 and CC80 [18]. Companion animals are usually colonised and infected with lineages typically seen in humans [4]. Cows are colonised and infected with their own different lineages that are rarely if ever found in humans, such as CC151, CC771, CC188, CC97, MK5108 mouse CC130 [14]. In contrast,

pigs can be colonised (but are rarely infected) with CC398, which has acquired mecA, and this lineage is capable of causing infection in humans [18, 19]. Poultry are susceptible to infection with CC5 isolates [20]. Furthermore, there are known to be wide variations in the distribution of lineages between different geographical

locations [21, 22]. A bounty of new S. aureus genome sequences has recently been released into the public domain. Our overall Endonuclease aim was to investigate genetic variation in S. aureus core and lineage-specific surface and immune evasion proteins compared to their cognate host proteins, to better identify which are the most likely to be essential during colonisation and infection. We compared whole genome sequences of the first 58 S. aureus genomes from 15 lineages and including 4 animal strains. We also extend our previous microarray analysis of human and animals isolates to include human MRSA lineages CC239, CC59 and CC80, and the pig MRSA clone CC398. Since our previous study, a number of new adhesion and immune evasion genes have been characterised, and these are also included in the analysis. Finally, we compared the known and putative human and animal protein targets that interact with S. aureus for genetic variation.