TY - JOUR
T1 - Comparative evaluation of trimeric envelope glycoproteins derived from subtype C and B HIV-1 R5 isolates
AU - Srivastava, Indresh K.
AU - Kan, Elaine
AU - Sun, Yide
AU - Sharma, Victoria A.
AU - Cisto, Jimna
AU - Burke, Brian
AU - Lian, Ying
AU - Hilt, Susan
AU - Biron, Zohar
AU - Hartog, Karin
AU - Stamatatos, Leonidas
AU - Cheng, R. Holland
AU - Ulmer, Jeffrey B.
AU - Barnett, Susan W.
PY - 2008/3/15
Y1 - 2008/3/15
N2 - We previously reported that an envelope (Env) glycoprotein immunogen (o-gp140ΔV2SF162) containing a partial deletion in the second variable loop (V2) derived from the R5-tropic HIV-1 isolate SF162 partially protected vaccinated rhesus macaques against pathogenic SHIVSF162P4 virus. Extending our studies to subtype C isolate TV1, we have purified o-gp140ΔV2TV1 (subtype C ΔV2 trimer) to homogeneity, performed glycosylation analysis, and determined its ability to bind CD4, as well as a panel of well-characterized neutralizing monoclonal antibodies (mAb). In general, critical epitopes are preserved on the subtype C ΔV2 trimer; however, we did not observe significant binding for the b12 mAb. The molecular mass of subtype C ΔV2 trimer was found to be 450 kDa, and the hydrodynamic radius was found to be 10.87 nm. Our data suggest that subtype C ΔV2 trimer binds to CD4 with an affinity comparable to o-gp140ΔV2SF162 (subtype B ΔV2 trimer). Using isothermal titration calorimetric (ITC) analysis, we demonstrated that all three CD4 binding sites (CD4-BS) in both subtype C and B trimers are exposed and accessible. However, compared to subtype B trimer, the three CD4-BS in subtype C trimer have different affinities for CD4, suggesting a cooperativity of CD4 binding in subtype C trimer but not in subtype B trimer. Negative staining electron microscopy of the subtype C ΔV2 trimer has demonstrated that it is in fact a trimer. These results highlight the importance of studying subtype C Env, and also of developing appropriate subtype C-specific reagents that may be used for better immunological characterization of subtype C Env for developing an AIDS vaccine.
AB - We previously reported that an envelope (Env) glycoprotein immunogen (o-gp140ΔV2SF162) containing a partial deletion in the second variable loop (V2) derived from the R5-tropic HIV-1 isolate SF162 partially protected vaccinated rhesus macaques against pathogenic SHIVSF162P4 virus. Extending our studies to subtype C isolate TV1, we have purified o-gp140ΔV2TV1 (subtype C ΔV2 trimer) to homogeneity, performed glycosylation analysis, and determined its ability to bind CD4, as well as a panel of well-characterized neutralizing monoclonal antibodies (mAb). In general, critical epitopes are preserved on the subtype C ΔV2 trimer; however, we did not observe significant binding for the b12 mAb. The molecular mass of subtype C ΔV2 trimer was found to be 450 kDa, and the hydrodynamic radius was found to be 10.87 nm. Our data suggest that subtype C ΔV2 trimer binds to CD4 with an affinity comparable to o-gp140ΔV2SF162 (subtype B ΔV2 trimer). Using isothermal titration calorimetric (ITC) analysis, we demonstrated that all three CD4 binding sites (CD4-BS) in both subtype C and B trimers are exposed and accessible. However, compared to subtype B trimer, the three CD4-BS in subtype C trimer have different affinities for CD4, suggesting a cooperativity of CD4 binding in subtype C trimer but not in subtype B trimer. Negative staining electron microscopy of the subtype C ΔV2 trimer has demonstrated that it is in fact a trimer. These results highlight the importance of studying subtype C Env, and also of developing appropriate subtype C-specific reagents that may be used for better immunological characterization of subtype C Env for developing an AIDS vaccine.
KW - CD4
KW - HIV
KW - ITC
KW - Neutralizing antibodies
KW - Subtype C
KW - Trimer
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U2 - 10.1016/j.virol.2007.10.022
DO - 10.1016/j.virol.2007.10.022
M3 - Article
C2 - 18061231
AN - SCOPUS:39649099788
VL - 372
SP - 273
EP - 290
JO - Virology
JF - Virology
SN - 0042-6822
IS - 2
ER -