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Journal of Virology, May 2009, p. 4476-4488, Vol. 83, No. 9
0022-538X/09/$08.00+0     doi:10.1128/JVI.02110-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Identification of a Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Variant Resistant to Cold Inactivation{triangledown} ,{dagger}

Aemro Kassa,1,3 Andrés Finzi,1 Marie Pancera,1,{ddagger} Joel R. Courter,2 Amos B. Smith III,2 and Joseph Sodroski1,3*

Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115,1 Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104,2 Department of Immunology & Infectious Disease, Harvard School of Public Health, Boston, Massachusetts 021153

Received 7 October 2008/ Accepted 25 January 2009

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein trimer consists of gp120 and gp41 subunits and undergoes a series of conformational changes upon binding to the receptors, CD4 and CCR5/CXCR4, that promote virus entry. Surprisingly, we found that the envelope glycoproteins of some HIV-1 strains are functionally inactivated by prolonged incubation on ice. Serial exposure of HIV-1 to extremes of temperature, followed by expansion of replication-competent viruses, allowed selection of a temperature-resistant virus. The envelope glycoproteins of this virus resisted cold inactivation due to a single passage-associated change, H66N, in the gp120 exterior envelope glycoprotein. Histidine 66 is located within the gp41-interactive inner domain of gp120 and, in other studies, has been shown to decrease the sampling of the CD4-bound conformation by unliganded gp120. Substituting asparagine or other amino acid residues for histidine 66 in cold-sensitive HIV-1 envelope glycoproteins resulted in cold-stable phenotypes. Cold inactivation of the HIV-1 envelope glycoproteins occurred even at high pH, indicating that protonation of histidine 66 is not necessary for this process. Increased exposure of epitopes in the ectodomain of the gp41 transmembrane envelope glycoprotein accompanied cold inactivation, but shedding of gp120 did not. An amino acid change in gp120 (S375W) that promotes the CD4-bound state or treatment with soluble CD4 or a small-molecule CD4 mimic resulted in increased cold sensitivity. These results indicate that the CD4-bound intermediate of the HIV-1 envelope glycoproteins is cold labile; avoiding the CD4-bound state increases temperature stability.

* Corresponding author. Mailing address: Dana-Farber Cancer Institute, 44 Binney Street—CLS 1010, Boston, MA 02115. Phone: (617) 632-3371. Fax: (671) 632-4338. E-mail: joseph_sodroski{at}dfci.harvard.edu

{triangledown} Published ahead of print on 11 February 2009.

{dagger} Supplemental material for this article may be found at http://jvi.asm.org/.

{ddagger} Present address: Vaccine Research Center, Building 40, National Institutes of Health, 40 Convent Drive, Bethesda, MD 20892.

Journal of Virology, May 2009, p. 4476-4488, Vol. 83, No. 9
0022-538X/09/$08.00+0     doi:10.1128/JVI.02110-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Kassa, A., Madani, N., Schon, A., Haim, H., Finzi, A., Xiang, S.-H., Wang, L., Princiotto, A., Pancera, M., Courter, J., Smith, A. B. III, Freire, E., Kwong, P. D., Sodroski, J. (2009). Transitions to and from the CD4-Bound Conformation Are Modulated by a Single-Residue Change in the Human Immunodeficiency Virus Type 1 gp120 Inner Domain. J. Virol. 83: 8364-8378 [Abstract] [Full Text]  


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