Passive neutralizing antibody controls SHIV viremia and enhances B cell responses in infant macaques

Maternal HIV-1-specific antibodies are efficiently transferred to newborns; their role in disease control is unknown. We administered non-sterilizing levels of neutralizing IgG, including the human neutralizing monoclonal IgG1b12, to six newborn macaques before oral challenge with SHIVSF612P3. All rapidly developed neutralizing antibodies and had significantly reduced plasma viremia for 6 months. These studies support the use of neutralizing antibodies in enhancing B cell responses and viral control in perinatal settings. Neutralizing antibodies (NAbs) increase in titer and avidity during HIV-1 infection1 and in many subjects mature to neutralize divergent isolates, targeting diverse epitopes on Envelope (Env). A fraction of NAbs target conserved regions on Env including the CD4 binding site (CD4bs) 2,3. HIV-1-positive pregnant mothers transfer HIV-1-specific IgG across the placenta to the fetus in utero and mother-to-child transmission frequently occurs in the presence of NAbs, which can mediate selection of transmitted variants4. Passiv