To this aim, we adopted an experimental protocol that was recently used to evaluate the GPI-anchored fusion inhibitor 2P2338, the rationale of which was based on the observation that coculturing CCR5-tropic HIV-infected CEMss-CCR5 cells (donor) with TZM-bl cells (target) resulted in rapid and efficient infection by the virus through a cell-cell pathway. The gene discussed is CCR5; the disease is infection.