BioText Search Engine

CD4-independent use of the CCR5 receptor by sequential primary SIVsm isolates

Laurén, A., Vincic, E., Hoshino, H., Thorstensson, R., Fenyö, E. (2007) Retrovirology.

ABSTRACT

Background CD4-independence has been taken as a sign of a more open envelope structure that is more accessible to neutralizing antibodies and may confer altered cell tropism. In the present study, we analyzed SIVsm isolates for CD4-independent use of CCR5, mode of CCR5-use and macrophage tropism. The isolates have been collected sequentially from 13 experimentally infected cynomolgus macaques and have previously been shown to use CCR5 together with CD4. Furthermore, viruses obtained... Show Full Abstract Background CD4-independence has been taken as a sign of a more open envelope structure that is more accessible to neutralizing antibodies and may confer altered cell tropism. In the present study, we analyzed SIVsm isolates for CD4-independent use of CCR5, mode of CCR5-use and macrophage tropism. The isolates have been collected sequentially from 13 experimentally infected cynomolgus macaques and have previously been shown to use CCR5 together with CD4. Furthermore, viruses obtained early after infection were neutralization sensitive, while neutralization resistance appeared already three months after infection in monkeys with progressive immunodeficiency. Results Depending whether isolated early or late in infection, two phenotypes of CD4-independent use of CCR5 could be observed. The inoculum virus (SIVsm isolate SMM-3) and reisolates obtained early in infection often showed a pronounced CD4-independence since virus production and/or syncytia induction could be detected directly in NP-2 cells expressing CCR5 but not CD4 (CD4-independent-HIGH). Conversely, late isolates were often more CD4-dependent in that productive infection in NP-2/CCR5 cells was in most cases weak and was revealed only after cocultivation of infected NP-2/CCR5 cells with peripheral blood mononuclear cells (CD4-independent-LOW). Considering neutralization sensitivity of these isolates, newly infected macaques often harbored virus populations with a CD4-independent-HIGH and neutralization sensitive phenotype that changed to a CD4-independent-LOW and neutralization resistant virus population in the course of infection. Phenotype changes occurred faster in progressor than long-term non-progressor macaques. The phenotypes were not reflected by macrophage tropism, since all isolates replicated efficiently in macrophages. Infection of cells expressing CCR5/CXCR4 chimeric receptors revealed that SIVsm used the CCR5 receptor in a different mode than HIV-1. Conclusion Our results show that SIVsm isolates use CCR5 independently of CD4. While the degree of CD4 independence and neutralization sensitivity vary over time, the ability to productively infect monocyte-derived macrophages remains at a steady high level throughout infection. The mode of CCR5 use differs between SIVsm and HIV-1, SIVsm appears to be more flexible than HIV-1 in its receptor requirement. We suggest that the mode of CCR5 coreceptor use and CD4-independence are interrelated properties. Shorten Abstract

VIEW FULL ARTICLE: HTML | PDF

Figures From Article (5)

FIGURE CAPTION

Figure 1. CD4-independent use of CCR5 by isolates obtained on hPBMC. NP-2/CCR5 cells were infected with virus stocks containing 2.7–3.5 log10 pg RT/well. The day after infection cultures were washed... Show Full Caption

FIGURE CAPTION

Figure 2. Intracellular and extracellular virus maturation shown by infection of hPBMC with lysates and supernatants of NP-2/CCR5 cultures. Seven days after infection, NP-2 cells were trypsinized, washed with PBS... Show Full Caption

FIGURE CAPTION

Figure 3. Mode of CCR5-use. A. Schematic figure of CCR5 and the chimeric receptors FC-1, FC-2 and FC-4b. The CCR5 part is represented as grey and the CXCR4 part as... Show Full Caption

FIGURE CAPTION

Figure 4. Replication capacity in macrophages of viruses isolated on hPBMC from progressors (A) versus slow progressors and LTNP (B). Macrophages were infected with virus stocks containing 3.0–3.1 log10 pg... Show Full Caption

FIGURE CAPTION

Figure 5. CD4-independence and neutralization sensitivity. Phenotypic changes in CD4-independence and sensitivity of neutralization over-time in 13 macaques. Neutralization sensitivity of three isolates (A, 2-week isolates, B, 3 or 4-month... Show Full Caption

Tables From Article (2)

TABLE CAPTION

Table 1. Comparison of the capacity to infect NP-2 cells by isolates on mPBMC or hPBMC.

Origin of cells for virus isolation	Isolate^a			NP-2/CD4/CCR5 syncytia^b	NP-2/CCR5 syncytia	NP-2/CCR5+PBMC virus production ^cRT (pg/ml)

	Monkey	Time PI (months)
mPBMC	D24	0.5		++++	+++	>1000
		3		++++	+	803
		10	§	+++	-	560
	C73	5	§	++++	++	>1000
		7	§	++++	++	649

Show Full Table (27 rows)

Origin of cells for virus isolation	Isolate^a			NP-2/CD4/CCR5 syncytia^b	NP-2/CCR5 syncytia	NP-2/CCR5+PBMC virus production ^cRT (pg/ml)

	Monkey	Time PI (months)
mPBMC	D24	0.5		++++	+++	>1000
		3		++++	+	803
		10	§	+++	-	560
	C73	5	§	++++	++	>1000
		7	§	++++	++	649
		18		++++	+	450
	C68	0.5	#	++	-	526
		30	#	++	-	674
		53	#	++	-	78
	B173	0.5		++++	+++	998
		39		++++	+	827
hPBMC	D24	0.5		+++	-	>1000
		3		++	-	713
		12	§	-	-	<50
	C73	0.5	§	++	-	573
		3	§	++	-	161
		18		++++	-	>1000
	C68	0.5		++++	-	<50
		3	§	++++	-	>1000
		30		++++	-	741
		53		++++	-	762
	B173	0.5		++++	+/-	>1000
		90	§	++	-	>1000
		39		+	-	85

Shorten Table

TABLE CAPTION

Table 1. Comparison of the capacity to infect NP-2 cells by isolates on mPBMC or hPBMC.

Origin of cells for virus isolation	Isolate^a			NP-2/CD4/CCR5 syncytia^b	NP-2/CCR5 syncytia	NP-2/CCR5+PBMC virus production ^cRT (pg/ml)

	Monkey	Time PI (months)
mPBMC	D24	0.5		++++	+++	>1000
		3		++++	+	803
		10	§	+++	-	560
	C73	5	§	++++	++	>1000
		7	§	++++	++	649

Show Full Table (27 rows)

Origin of cells for virus isolation	Isolate^a			NP-2/CD4/CCR5 syncytia^b	NP-2/CCR5 syncytia	NP-2/CCR5+PBMC virus production ^cRT (pg/ml)

	Monkey	Time PI (months)
mPBMC	D24	0.5		++++	+++	>1000
		3		++++	+	803
		10	§	+++	-	560
	C73	5	§	++++	++	>1000
		7	§	++++	++	649
		18		++++	+	450
	C68	0.5	#	++	-	526
		30	#	++	-	674
		53	#	++	-	78
	B173	0.5		++++	+++	998
		39		++++	+	827
hPBMC	D24	0.5		+++	-	>1000
		3		++	-	713
		12	§	-	-	<50
	C73	0.5	§	++	-	573
		3	§	++	-	161
		18		++++	-	>1000
	C68	0.5		++++	-	<50
		3	§	++++	-	>1000
		30		++++	-	741
		53		++++	-	762
	B173	0.5		++++	+/-	>1000
		90	§	++	-	>1000
		39		+	-	85

Shorten Table