Table 1. Comparison Between Multiple and Single Round Infectivity Assays.

	Multiple Round Assays	Single Round Assays
Cell Type Infected	Cell lines or in vitro activated PBMC	Cell lines or CD4+T cells isolated from in vitro activated PBMC
Assay Read-Out	p24 antigen, RT activity, cell viability	Luciferase or GFP
Read-Out Sensitivity	Population level	Population level or single cell level (GFP assay)
Time to Reach End-Point	> 5 days	≤ 7 days
Dynamic Range	< 4 logs	≥ 3 logs
High Throughput Capacity	Poor	Good
Reproducibility	Variable	Good
Viral Evolution During Assay	Possible	No
Type of Drug Inhibition Measured	Cumulative	Instantaneous
Ability to Measure Slope	No	Yes
Ability to Measure IIP	No	Yes