IFNB1 and infection: Interestingly, both Slamf1-/- macrophages Y and VFRA infections and BALB/c macrophages infected by VFRA shared the response to IFN-β, suggesting that in the BALB/c with the Y strain, this protective immune response is not so effective, as in VFRA the absence of SLAMF1 would allow the correct activation of this pathway.