SIGLEC1 and infection: Interestingly, MLV-MA-chimeric HIV was unique in its inability to activate MDMs, since infection of MDMs with lentiviruses encoding chimeric Gag with MA sequences derived from other lentiviruses (HIV-2, SIVmac, SIVagm, SIVcpz, SIVgor, FIV or EIAV) or deltaretrovirus (HTLVII) (Supplementary Fig. 4i, l) upregulated CD169 and IP-10 expression (Supplementary Fig. 4j, k, m, n).