Table 1.

Cofactor utilization, target cell entry, and tropism of viruses testeda

VirusM tropismT tropism
CCR5 usageEntry into MDMReplication in MDMCXCR-4 usageEntry into MT-2Replication in MT-2
89.6++++++
JRFL+++
HXB+++
89-v345.FL++++++
89-v345.HX++++++
89-v3.HX++++++
89-v45.HX++++++
HX-v345.89+++++
HX-v3.89+++++
  • a CCR5 and CXCR-4 utilization was determined by PCR-based entry into QT6.CD4 cells transfected with the respective chemokine receptors and/or by Env-mediated fusion. Target cell entry was determined by PCR detection of early (LTR) reverse-transcription products after infection with cell-free virus, and replication was determined by detection of viral p24 Gag antigen in supernatant as previously described (23).