FIG. 3.

(A) Attachment. BMECs (Cell System Corp.) were exposed to 10 ng of p24 of HIV-1 pNL4.3 (wild type) or pNL4.3-E (gp160 deficient) virus at 37°C. After different intervals of time, cells were washed, detached, and lysed. Amounts of attached virus were determined by p24 ELISA of cell lysates. (B) Internalization. HIV-1 was added to BMECs as described above, and at different intervals of time, cells were washed, trypsinized, washed again, and immediately lysed. Amounts of internalized HIV-1 were quantified by p24 ELISA of cell lysates. (C) Transcytosis. HIV-1 was added to the apical surface of BMECs, and amounts of transcytosed viruses were quantified by p24 ELISA in the lower chamber, corresponding to the basal surface. Results are representative of those from two independent experiments.