The intracellular plasma membrane-connected compartment in the assembly of HIV-1 in human macrophages

Table 1 Quantitation of virus buds and membrane lengths for cryosections of MDMs infected with budding-arrested HIV-1 mutants

Mutant	No. of cell profiles analysed^a	Cell surface			IPMC			% of buds in IPMC	Enrichment of buds in IPMC^b
Mutant	No. of cell profiles analysed^a	No. of virus buds	μm of membrane	Buds/μm of membrane	No. of virus buds	μm of membrane	Buds/μm of membrane	% of buds in IPMC	Enrichment of buds in IPMC^b
PTAP^–
D415^c	7 (5)	26	2620	0.0099	1137	1378	0.8248	97.8	83 ×
PTAP^–YP^–
D428	9 (5)	4	2041	0.0020	719	931	0.7723	99.4	394 ×
D429	12 (11)	89	5278	0.0169	1149	1814	0.6333	92.8	38 ×
D432	6 (5)	44	2486	0.0177	417	483	0.8633	90.5	49 ×
Overall total	34 (26)	163	12,424	0.0131	3422	4607	0.7428	95.5	57 ×

Monocyte-derived macrophages (MDMs) from four different donors were infected with the HIV-1 R3A mutants PTAP^– or PTAP^–YP^–, and infected MDMs located by on-grid immunolabelling. Electron microscopy images were recorded and analysed by counting the number of virus buds seen either at the cell surface or within intracellular plasma membrane-connected compartment (IPMCs). Linear lengths of surface or IPMC membrane within the sections were measured by tracing (see Methods)
^a The number of cell profiles for which viral buds were counted and membrane lengths measured (the number of distinct cells analysed is given in brackets)
^b The ratio of the density of buds/μm of membrane in the IPMC compared to the cell surface is shown as fold enrichment
^c Donor ID