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

Laurén, Anna LU ; Vincic, Elzbieta LU ; Hoshino, Hiroo; Thorstensson, Rigmor and Fenyö, Eva Maria LU (2007) In Retrovirology 4.
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Retrovirology
volume
4
publisher
BioMed Central
external identifiers
  • wos:000249027000001
  • scopus:34548207713
ISSN
1742-4690
DOI
10.1186/1742-4690-4-50
language
English
LU publication?
yes
id
43788a54-7fb9-47fe-85b4-4e6d63a9ffad (old id 687012)
date added to LUP
2007-12-14 13:25:31
date last changed
2017-01-01 07:02:07
@article{43788a54-7fb9-47fe-85b4-4e6d63a9ffad,
  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.},
  author       = {Laurén, Anna and Vincic, Elzbieta and Hoshino, Hiroo and Thorstensson, Rigmor and Fenyö, Eva Maria},
  issn         = {1742-4690},
  language     = {eng},
  publisher    = {BioMed Central},
  series       = {Retrovirology},
  title        = {CD4-independent use of the CCR5 receptor by sequential primary SIVsm isolates},
  url          = {http://dx.doi.org/10.1186/1742-4690-4-50},
  volume       = {4},
  year         = {2007},
}