Bo Zhao

Publications (2)8.19 Total impact

• Article: Highly potent chimeric inhibitors targeting two steps of HIV cell entry.

  Bo Zhao, Marie K Mankowski, Beth A Snyder, Roger G Ptak, Patricia J Liwang
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  ABSTRACT: Blocking HIV-1 cell entry has long been a major goal of anti-HIV drug development. Here, we report a successful design of two highly potent chimeric HIV entry inhibitors composed of one CCR5-targeting RANTES (regulated on activation normal T cell expressed and secreted) variant (5P12-RANTES or 5P14-RANTES (Gaertner, H., Cerini, F., Escola, J. M., Kuenzi, G., Melotti, A., Offord, R., Rossitto-Borlat, I., Nedellec, R., Salkowitz, J., Gorochov, G., Mosier, D., and Hartley, O. (2008) Proc. Natl. Acad. Sci. U.S.A. 105, 17706-17711)) linked to a gp41 fusion inhibitor, C37. Chimeric inhibitors 5P12-linker-C37 and 5P14-linker-C37 showed extremely high antiviral potency in single cycle and replication-competent viral assays against R5-tropic viruses, with IC(50) values as low as 0.004 nm. This inhibition was somewhat strain-dependent and was up to 100-fold better than the RANTES variant alone or in combination with unlinked C37. The chimeric inhibitors also fully retained the antiviral activity of C37 against X4-tropic viruses, and this inhibition can be further enhanced significantly if the target cell co-expresses CCR5 receptor. On human peripheral blood mononuclear cells, the inhibitors showed very strong inhibition against R5-tropic Ba-L strain and X4-tropic IIIB strain, with IC(50) values as low as 0.015 and 0.44 nm, which are 45- and 16-fold better than the parent inhibitors, respectively. A clear delivery mechanism requiring a covalent linkage between the two segments of the chimera was observed and characterized. Furthermore, the two chimeric inhibitors are fully recombinant and are easily produced at low cost. These attributes make them excellent candidates for anti-HIV microbicides. The results of this study also suggest a potent approach for optimizing existing HIV entry inhibitors or designing new inhibitors.
  Journal of Biological Chemistry 06/2011; 286(32):28370-81. · 4.77 Impact Factor
• Article: Characterization of the interactions of vMIP-II, and a dimeric variant of vMIP-II, with glycosaminoglycans.

  Bo Zhao, Patricia J Liwang
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  ABSTRACT: Chemokines are important immune proteins, carrying out their function by binding to glycosaminoglycans (GAGs) on the endothelial surface and to cell surface chemokine receptors. A unique viral chemokine analogue, viral macrophage inflammatory protein-II (vMIP-II), encoded by human herpesvirus-8, has garnered interest because of its ability to bind to multiple chemokine receptors, including both HIV coreceptors. In addition, vMIP-II binds to cell surface GAGs much more tightly than most human chemokines, which may be the key to its anti-inflammatory function in vivo. The goal of this work was to determine the mechanism of binding of GAG by vMIP-II. The interaction of vMIP-II with a heparin-derived disaccharide was characterized using NMR. Important binding sites were further analyzed by mutagenesis studies, in which corresponding vMIP-II mutants were tested for GAG binding ability using heparin chromatography and NMR. We found that despite having many more basic residues than some chemokines, vMIP-II shares a characteristic binding site similar to that of its human analogues, utilizing basic residues R18, R46, and R48. Interestingly, a particular mutation (Leu13Phe) caused vMIP-II to form a pH-dependent CC chemokine-type dimer as determined by analytical ultracentrifugation and NMR. To the best of our knowledge, this is the first example of engineering a naturally predominantly monomeric chemokine into a dissociable dimer by a single mutation. This dimeric vMIP-II mutant binds to heparin much more tightly than wild-type vMIP-II and provides a new model for studying the relationship between chemokine quaternary structure and various aspects of function. Structural differences between monomeric and dimeric vMIP-II upon GAG binding were characterized by NMR and molecular docking.
  Biochemistry 08/2010; 49(33):7012-22. · 3.42 Impact Factor