. 2006 Nov 1;81(2):525–531. doi: 10.1128/JVI.01983-06

TABLE 2.

Autologous serum neutralization titers of early and late post-X4 virus clones of ACH0171

Clone	Time since X4 (mo)^a	Phenotype	Neutralization titer (IC₅₀) at mo since X4^a,b
Clone	Time since X4 (mo)^a	Phenotype	−16.2	−7.5	10.5	27.0
171.31.ROF6	4.5	R5	125	79	69	87
171.33.ROA1	10.5	R5	87	84	81	114
171.41.ROE2	27.0	R5	<40	<40	<40	<40
171.41.ROC5	27.0	R5	<40	<40	<40	<40
171.31.ROB9	4.5	R5X4	>1,280	>1,280	>1,280	>1,280
171.33.ROA2	10.5	R5X4	151	768	343	NT
171.41.D12	27.0	R5X4	84	<40	82	<40
171.41.RAF5	27.0	R5X4	51	<40	<40	80

Months since X4 variant was detected.

Neutralization was determined by 7-day culture of clonal virus isolates on PBMC in the presence or absence of serial dilutions of serum, followed by analysis of p24 production by ELISA. IC₅₀s were determined by linear regression after subtracting the inhibition obtained using human pooled HIV-1-negative serum.