An Automated Fluorescence-Based Method to Isolate SIVmac239-Specific Bone Marrow-Derived Plasma Cells from Indian Rhesus Macaques using SIVmac239 SOSIP.664

Abstract Simian immunodeficiency virus (SIV)-infection of Indian rhesus macaques (RMs) is one of the best characterized animal models for human immunodeficiency virus (HIV) infection. Monoclonal antibodies (mAbs) have shown promise in the prevention and treatment of HIV infection. However, it has been difficult to isolate mAbs that potently neutralize the highly pathogenic SIVmac239 strain. This has been largely due to the low frequency of circulating B cells encoding neutralizing Abs. Here, we describe a novel technique to isolate mAbs directly from bone marrow-derived, Ab-secreting plasma cells. We employed an automated micromanipulator to isolate single SIVmac239 SOSIP.664-specific plasma cells from the bone marrow of a SIVmac239-infected RM with serum neutralization titers against SIVmac239. After picking plasma cells, we obtained 44 paired Ab sequences. Ten of these mAbs were SIV-specific. While none of these mAbs neutralized SIVmac239, three mAbs completely neutralized the related SIVmac316 strain. The majority of these mAbs bound to primary rhesus CD4+ T cells infected with SIVmac239, and induced Ab-dependent cellular cytotoxicity. This method represents a first step in the successful isolation of antigen-specific bone marrow-derived plasma cells from RMs.Pedreno-Lopez and colleagues adapted a previously described innovative fluorescence-based method to isolate antigen-specific plasma cells from total bone marrow of rhesus macaques using a micromanipulator. This method facilitated the isolation and subsequent characterization of SIV-specific non-neutralizing antibodies with antibody-dependent cellular cytotoxicity activity that might be efficacious in vivo.