Neutralizing Antibody Evaluation with PhenoSense Assay

The PhenoSense™ HIV neutralization assay was performed by Monogram Biosciences, Inc. using the U87 target cell line expressing CD4, CCR5, and CXCR4, as previously described [32] (link), [49] (link). The U87 cell line was generated by Dr. Nathaniel Landau (New York University School of Medicine, New York, NY). This single round replication assay was used to test 57 psVs expressing cloned Env gene populations extracted from viruses in patients' plasma. The psVs were first treated with 2- or 3-fold serial dilutions of mAbs starting from 50 µg/ml, and then incubated with the U87 cells. After 72 hr, the levels of virus infection were assessed by measuring luciferase activity. In this assay, the anti-parvovirus mAb 860-55D (designated here as 860) and an aMLV Env-expressing psV were used as negative controls, whereas psVs expressing cloned Envs of SF162, JR-CSF, and NL4.3 were tested as positive controls.