doi: 10.1126/science.aaf1279. between published Env-pseudotyped virus panels and PBMC-derived primary isolates. Utilizing clonal PBMC-derived primary isolates and molecular clones, we decided that the observed discrepancy in bNAb performance is due to the increased sensitivity to neutralization exhibited by 293T-produced Env-pseudotyped viruses. We also found that while full-length molecularly cloned viruses produced in 293T cells exhibit greater sensitivity to neutralization than PBMC-derived viruses do, Env-pseudotyped viruses produced RKI-1313 in 293T cells generally exhibit even greater sensitivity to neutralization. As the clinical development of bNAbs progresses, it will be critical to determine the relevance of each of these neutralization assays to antibody performance. IMPORTANCE Novel therapeutic and preventive strategies are needed to contain the HIV-1 epidemic. Antibodies with exceptional neutralizing activity against HIV-1 may provide several advantages to traditional HIV drugs, including an improved side-effect profile, a reduced dosing frequency, RKI-1313 and immune enhancement. The activity of these antibodies has been established by utilizing HIV-1 Env-pseudotyped viruses derived from circulating viruses but produced in 293T cells by pairing Env proteins with a backbone vector. We tested PBMC-produced circulating viruses against five anti-HIV-1 antibodies currently in clinical development. We found that the activity of these antibodies against PBMC isolates is usually significantly less than that against 293T Env-pseudotyped viruses. This decline varied among the antibodies tested, with some demonstrating moderate reductions in activity and others showing an almost 100-fold reduction. As the development of these antibodies progresses, it will be critical to determine how the results of different assessments correspond to performance in the clinic. based70 (45)????Combination or other10 (6) Open in a separate window aIQR, interquartile range. bNNRTI, nonnucleoside reverse transcriptase inhibitor. All of the participants included in this analysis were U.S. residents at the time of PBMC collection and were therefore likely to be infected with clade B viruses. Twenty-four participants tested by sequencing were indeed found to be infected with clade B viruses. Therefore, neutralization results from the PBMC-derived primary isolates were compared with those from the clade B pseudoviruses in the original panels used to characterize each antibody (2,C5, 7). PBMC-derived primary isolates obtained from bulk outgrowth cultures were tested in the TZM-bl cell neutralization assay against five bNAbs that target different epitopes around the HIV-1 envelope: 3BNC117 and VRC01 (CD4 binding site), 10-1074 (V3 glycan), PGDM1400 (V1/V2 glycan), and 10E8 (membrane-proximal external region [MPER]). We found that every bNAb tested demonstrated less neutralization breadth and potency against the PBMC-derived primary isolates than against the original pseudovirus panels (Fig. 1a). Of RKI-1313 note, the magnitude of this decline varied among the bNAbs tested, with the fold differences between the geometric mean 50% inhibitory concentrations (IC50s) of the two groups ranging from 3.3 for PGDM1400 to 92.2 for 10E8, which displayed the greatest disparity and was also the least potent against the primary isolates (Fig. 1b). Open in a separate window FIG 1 Breadth and potency of bNAbs against PBMC-derived primary isolates compared to those of original pseudovirus panels. (a) For each antibody, the graph around the left shows the percentage of viruses neutralized in the TZM-bl cell assay at a given IC50 (g/ml) for the original clade B pseudovirus panels (black) and for PBMC-derived primary isolates (in color). N is the number of viruses tested in the original pseudovirus panel (black) and the PRKM9 PBMC-derived primary isolates (colored). The graph on the right shows the IC50 (g/ml) for each isolate in the original pseudovirus (PV) panels and the PBMC-derived primary.
