IL6 and infection: To determine whether the attenuated virulence of the SCVs in zebrafish were caused by lipoproteins due to immune response mediated by TLR2, we evaluated the virulence of the three mutants ΔsurA/SCV1, Δslp/SCV1, and ΔlpoB/SCV1 in zebrafish and investigated the expression levels of TLR2, TNF-α, IL-1β, and IL-6 in RAW264.7 macrophages in response to infection with the mutants.