CSN1S1 and infection: The CA-SA ST398 could produce multitudes of external toxins, enhancing its invasive ability and easily causing the more severe infections in healthy individuals, while ST239 produce higher amounts of protein A. To explore the higher expression of protein A in the pathogenicity of ST239 infections, we then developed a mouse renal abscess model with sublethal challenged bacteria WT Ji99 and its isogenic spa mutant strain, and evaluated the severity of infection by enumerating staphylococcal CFU per kidney.