Identification of an unique CXCR4 epitope whose ligation inhibits infection by both CXCR4 and CCR5 tropic human immunodeficiency type-I viruses

Table 1 Suppressive effect of the A120 mAb on various clades of HIV-1 strains.

Member	HIV-1 Subtype	Isolate	Country of Origin	Syncytium	Co-receptor Usage	Percent inhibition of p24 production
PRD320-01	A	UG275	Uganda	NSI	CCR5	88.3%
PRD320-02	A	I-2496	Ghana	NSI	CCR5	99.8%
PRD320-03	CRF02_AG	DJ263	Djibouti	NSI	CCR5	94.7%
PRD320-04	CRF02_AG	POC44951	Liberia	NSI	CCR5	99.7%
PRD320-06	B	BZ167	Brazil	SI	CXCR4	97.2%
PRD3200-7	C	DJ259	Djibouti	NSI	CCR5	91.5%
PRD320-08	C	ZAM18	Zambia	NSI	CCR5	93.7%
PRD320-09	D	SE365	Senegal	SI	CXCR4	98.5%
PRD320-10	D	UG270	Uganda	SI	CXCR4	99.7%
PRD320-11	CRF01_AE	ID17	Indonesia	NSI	CCR5	81.0%
PRD320-12	CRF01_AE	NP03	Thailand	SI	CXCR4	94.5%
PRD320-14	F	BCI-R07	Romania	SI	CXCR4/CCR5	99.4%
PRD320-15	G	BCF-DIOUM	Zaire	NSI	CCR5	99.9%
PRD320-16	G	HH8793	Kenya	NSI	CCR5	83.3%
PRD320-17	H	BCF-KITA	Zaire	NSI	CCR5	92.5%
PRD320-18	O	BCF06	Cameroon	SI	CXCR4/CCR5	98.3%
PRD320-19	O	I-2478B	US	NSI	CCR5	65.6%

Anti-CD3/CD28 activated PBMCs were infected with each of 15 different HIV-1 strains belonging to various clades and with previously defined different CXCR4 and CCR5 usages. HIV-1 dose of 10 ng p24 value was added to 1 × 10⁶ cells for infection. After washing, PBMCs were aliquoted and cultured in triplicate in the presence of 10 μg/ml of the A120 mAb or isotype control IgG for 5 days. Virus production was determined by quantitation of p24 in the culture supernatants by ELISA and the mean values calculated. Percent inhibition was calculated relative to the values obtained with the isotype control mAb alone. Representative data from three independent experiments are shown.