A hollow-fiber bioreactor for expanding HIV-1 in human lymphocytes used in preparing an inactivated vaccine candidate

Abstract

An inactivated HIV vaccine intended to elicit broadly neutralizing antibodies is designed to use a pool of population-prevalent HIV-1 from plasma (PHIV), isolated before evolution of antibody-mediated genetic mutations. A suitable cell substrate (CS) for isolating such PHIV is peripheral blood mononuclear cells (PBMC) after stimulating with phytohemagglutinin (PHA) and interleukin-2 (IL-2). Feasibility of employing a hollow-fiber bioreactor under optimized conditions was investigated for large-scale expansion and efficient recovery of concentrated PHIV. Each CS batch was infected in vitro with a prototype PHIV, the infected cells were introduced into the bioreactor for 7–10 days in co-culture, and the cell-free supernatants were assayed for p24 antigen as an index of HIV synthesis. PBMC versus CD8-depleted (CD8D) CS, 20 kDa versus 5 kDa molecular weight cut-off (MWCO) bioreactor cartridges, 7- versus 10-day culture periods, and varying concentrations of IL-2, fetal bovine serum (FBS) and glucose content in the medium were functionally evaluated for p24 yield. PBMC cultures in 20 kDa MWCO cartridges with 15% FBS, 80 IU/mL IL-2 and 2.0 g/L glucose produced the highest p24 yield; however, CD8D-CS, 20–30% FBS and 80 IU/mL IL-2 within 5 kDa cartridges and 2.0 g/L glucose in the circulating medium was more cost-effective for synthesis of virion p24.