Fig. 2. IgG subclass switching does not affect the ability of VRC07 to protect from HIV challenge in huPBMC-NSG mice.

(A) Overview of the huPBMC-NSG mouse model with a schematic representation of the experimental timeline. IP, intraperitoneal. (B) In vitro neutralization activity of purified VRC07 IgG subclasses against the challenge strain, HIV_NL4-3, was measured by a TZM-bl neutralization assay (n = 12 per group). The horizontal dashed line indicates 50% neutralization activity. Error bars represent SEM. (C) Average plasma antibody concentrations achieved in NSG mice were measured by ELISA after intramuscular injection of 2.5 × 10¹¹ genome copies (GC) of AAV expressing a given VRC07 IgG subclass or firefly luciferase (control) as a negative control (n = 8 to 12 mice per group). Error bars represent SEM. The horizontal dashed line indicates the limit of detection, 0.02 μg/ml, for the assay. (D) CD4 T cell depletion (left) and viral load (right) were measured in the peripheral blood of huPBMC-NSG mice expressing luciferase (control) or a VRC07 IgG subclass after intravenous challenge of 280 TCID50 HIV_NL4-3. Viral load was measured by qPCR. The dotted lines indicate the limit of detection, 1000 copies/ml. Samples with undetectable viral load were assigned an arbitrary value below the limit of detection. CD4 depletion was measured by flow cytometry. The dashed lines indicate mice that were confirmed to be infected by qPCR. (E) Kaplan-Meier survival curves for huPBMC-NSG mice expressing the given VRC07 IgG subclass or negative control. Survival curves of all VRC07 IgG subclasses were significantly different as compared to control (P < 0.0001) by log-rank (Mantel-Cox) test.