Relative infection of pseudotyped CA mutant viruses. Infectivity of normalized amounts (10,000 cpm RTase activity) of WT viruses and CA mutants expressing HIV-1 envelope (A) or having incorporated MLV (B) or VSV (C) glycoprotein was monitored using the MAGIC-5B indicator cell line. (C) Replication of VSV-G pseudotyped WT and CA mutants (10,000 cpm RTase activity) was inhibited by addition of 20 μM AZT to the culture medium. Values are expressed as a percentage of WT infectivity. (D) Rescue of CA mutant infectivity by VSV-G pseudotyping was investigated at low infectious doses (100 to 1,000 cpm RTase activity) by measuring o-nitrophenyl β-D-galactopyranoside hydrolysis in MAGIC-5B. Each value represents an average of three experiments performed in duplicate ± standard deviation.