Title: CXCR4 antagonistinduced coreceptor switch from X4 to R5 phenotype in vitro determined by a single am
1CXCR4 antagonist-induced coreceptor switchfrom
X4 to R5 phenotype in vitro determined by a
single amino acid substitution in the V3 region
of human immunodeficiency virus type 1 gp120
Maeda Y, Yusa K, Harada S. Kumamoto University,
Graduate School of Medical Sciences, Department
of Medical Virology, Kumamoto, Japan
2Coreceptor switch of HIV-1 in vivo
- CCR5-using viruses (called R5 viruses) are
associated with transmission between human, and
are predominant throughout the course of
infection. - CXCR4-using viruses emerge at late stage of
infection, and are associated with accelerated
disease progression.
3Inhibitors of Coreceptor Engagement
4Coreceptor switch of HIV-1 in vitro
- The coreceptor switch has not been reproduced in
vitro under selective pressure by coreceptor
inhibitors although the target cells express both
coreceptors.
5Characteristics of R5X4 viruses
- Most of CXCR4-using viruses retain to use CCR5
called R5X4 viruses. - Replication of R5X4 viruses is blocked by CXCR4
inhibitors alone in the cells expressing both
CCR5 and CXCR4.
6Sensitivity of various strains of HIV-1 to
coreceptor inhibitors
Numbers represent mean EC50 values (nM) of
TAK-779 and T140 in indicated cells
7In vitro study of coreceptor switch
- Cell PM1/CCR5
- Virus 89.6 strain (R5X4 variant)
- Inhibitor T140 (CXCR4 antagonist)
8Sensitivity of T140-escape mutant passaged in
PM1/CCR5 determined by MAGI/CCR5
9V3 region amino acid sequences from 89.6-infected
cells passaged and selected in T140
-
- wild 89.6 CTRPNNNTRRRLSIGPGRAFYARRNIIGDIRQAHC
- T140(-) ...................................
9/9 - T140() ..........S........................
8/12 - ...................................
3/12 - ........................S..........
1/12
308
10Construction of 89.6 envelope expression vector
carrying Afl II and Nhe I
Produce luciferase-reporter HIV with Envs Check
sensitivity to coreceptor inhibitors
11The substitution R308S conferred total resistance
to T140 in NP2/CD4/CCR5/CXCR4 cells
12The substitution R308S conferred cross-resistance
to AMD3100in NP2/CD4/CCR5/CXCR4 cells
13The substitution R308S conferred increased
sensitivity to TAK-779in NP2/CD4/CCR5/CXCR4 cells
14Phenotype switch from X4 to R5 in PBMC
15Coreceptor usage of various Envs in NP2/CD4 cell
line expressing single coreceptor
16The sensitivities of various Envs to coreceptor
inhibitors in single coreceptor expressing cells
Numbers represent mean EC50 values (nM) of
coreceptor inhibitors in indicated cells. NA not
applicable
17Conclusion (I)
- A single amino acid substitution (R308S) in the
89.6 Env conferred total resistance to T140 and
AMD3100 but increased sensitivity to TAK-779 in
the infection of cells expressing both
coreceptors.
18Conclusion (II)
- The mutation R308S was correlated with increased
affinity of the Env for CCR5. - The 89.6 strain carrying R308S is likely to be
reverted from X4 to intermediate or transitional
phenotype close to R5 viruses.
19Conclusion (III)
- The use of R5X4 viruses is important to induce
coreceptor switch in vitro.