GHOST (a–c) or HeLa TZM bl (d–f) indicator cell lines were infected with WT NL4.3 (Ba-L Env) or NL4.3 (Ba-L Env) bearing CA mutations N74D or P90A at low multiplicity (0.04). Replication was monitored by GFP expression (GHOST) or staining LacZ positive cells (HeLa TZM bl). Both mutants replicated well, slightly behind wild-type virus. Replication in GHOST (b) or HeLa TZM bl (e) was performed in the presence of IFNAR2 antibody or isotype cAb. Neither antibody had any effect on WT or mutant HIV-1 replication in GHOST or HeLa TZM bl indicator cell lines. c, f, Induction of ISGs IP10 and IFIT1 expression were measured by quantitative RT PCR after high multiplicity infection (MOI 2) by WT or CA mutant HIV-1 on GHOST (c) or HeLa TZM bl (f). 10 ng ml−1 of IFN-β treatment acted as a positive control. ISG expression levels were normalized to GAPDH and are expressed as fold change in expression over unstimulated cells (Mean of 3 replicates ± s.e.m.). Neither WT or CA mutant HIV-1 induced ISG expression in either cell line. g, HeLa TZM bl were infected WT or CA G89V at low multiplicity (0.04). Replication was monitored by staining LacZ positive cells. h, HIV-1 CA G89V replication in HeLa TZM bl was defective and not rescued by anti-IFNAR2 or isotype control antibodies. All results are representative of 2 biological replicates.