Comparative evaluation of trimeric envelope glycoproteins derived from subtype C and B HIV-1 R5 isolates

Indresh K. Srivastava, Elaine Kan, Yide Sun, Victoria A. Sharma, Jimna Cisto, Brian Burke, Ying Lian, Susan Hilt, Zohar Biron, Karin Hartog, Leonidas Stamatatos, R. Holland Cheng, Jeffrey B. Ulmer, Susan W. Barnett

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)273-290
Number of pages18
Issue number2
StatePublished - Mar 15 2008


  • CD4
  • HIV
  • ITC
  • Neutralizing antibodies
  • Subtype C
  • Trimer

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases


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