To begin to identify the step in the HIV-1 replication cycle that is impaired by downmodulation of CIB1 and CIB2, we infected Jurkat cells with envelope-defective pseudotyped viruses and measured the accumulation of intracellular Gag at 48 h, such that only the early steps of infection in a single cycle up to viral protein synthesis were evaluated. The gene discussed is CIB1; the disease is infection.