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Emma Mohr

Mentor: Jack Stapleton, M.D.
Lab Room: Bldg. 40, Room 104 VAMC
Lab Phone: 158-7586

Characterization of GBV-C envelope glycoproteins

GB virus C (GBV-C) is a nonpathogenic flavivirus associated with prolonged survival in HIV-infected individuals. Approximately 2% of healthy blood donors have GBV-C viremia and infection can persist for years. Although multiple clinical studies have published that GBV-C viremia decreases mortality and improves clinical outcome in HIV-positive individuals, the mechanisms for these interactions have not been completely elucidated. So far, GBV-C has been found to inhibit HIV entry, HIV replication, and alter cytokine, chemokine and chemokine receptor profiles. Specifically, GBV-C downregulates the expression of one of the coreceptors for HIV, CCR5, in T lymphocytes, and increases the secretion of HIV-inhibitory cytokines RANTES, MIP1a, MIP1 and SDF-1. Although GBV-C envelope 2 (E2) has been shown to specifically inhibit HIV entry, little is known about the structure of GBV-C envelope proteins, their cellular receptors, early viral entry steps, or mechanisms of HIV inhibition. Studies of the envelope proteins have been hampered because no efficient cell cultures systems exist to allow the study of complete viral life cycles. To this end, I am examining the cell specificity of lentivirus pseudoparticles decorated with envelope proteins 1 and 2 and the binding characteristics of recombinant E2 to identify cellular binding and entry receptors, respectively, and to study early entry steps. Cellular binding and viral entry profiles have been generated for multiple cell lines, and candidate binding and entry receptors have been identified by correlating binding or entry profiles with mRNA expression profiles. Further studies to assess candidate receptors with siRNA knockdown are underway.

Xiang J, McLinden JH, Kaufman TM, Mohr EL, Bhattarai N, Chang Q, Stapleton JT. Characterization of a peptide domain within the GB virus C envelope glycoprotein (E2) that inhibits HIV replication. Virology. 2012 Aug 15;430(1):53-62. Epub 2012 May 16. PubMed PMID: 22608061.

Mohr EL, Murthy KK, McLinden JH, Xiang J, Stapleton JT. The natural history of non-human GB virus C in captive chimpanzees. J Gen Virol. 2011 Jan;92(Pt 1):91-100. Epub 2010 Sep 22. PubMed PMID: 20861317; PubMed Central PMCID:PMC3052534.

Mohr EL, Xiang J, McLinden JH, Kaufman TM, Chang Q, Montefiori DC, Klinzman D, Stapleton JT. GB virus type C envelope protein E2 elicits antibodies that react with a cellular antigen on HIV-1 particles and neutralize diverse HIV-1 isolates. J Immunol. 2010 Oct 1;185(7):4496-505. Epub 2010 Sep 8. PubMed PMID: 20826757.

Mohr EL, Stapleton JT. GB virus type C interactions with HIV: the role of envelope glycoproteins. J Viral Hepat. 2009 Nov;16(11):757-68. Epub 2009 Sep 15. Review. PubMed PMID: 19758271.

Honors and Awards

  • 2009 Best Poster - University of Iowa Department of Internal Medicine Research Day