To current convention [46]). C34-Ig was produced and purified as previously described [47]. The CD4-Ig fusion protein consists of the first two N-terminal domains of the CD4 molecule and the Fc region of human IgG1. Purification was carried out as described for the C34-Ig molecule [47].mechanism of sCD4 neutralization [17,18]. Resistance to sCD4 may thus arise by a decreased affinity of the envelo