Irreversible breakdown of HIV-1 by peptide triazole thiols and multivalent gold nanoparticle conjugates

The HIV entry is a critical multi-stage process which leads to attachment to the cell receptor followed by co-receptor binding leading to a conformation change in the HIV envelope spike leading to membrane fusion. The peptide triazoles developed in the Chaiken lab has previously been established to function as dual antagonists of the binding of gp120 at its host cell receptor binding sites for both CD4 and CCR5/CXCR4 and have shown to have broad neutralization In Vitro. In this work we showed that a representative member of this class, peptide triazole thiol, led to HIV inhibition but also leads to irreversible lysis and complete inactivation of cell-free HIV-1. Further to improve the potency of these peptide triazole thiol inhibitors, I created multivalent displays of KR13 on gold nanoparticles that led to a drastic potency increase in inhibition of HIV-1. My research is focused on understanding the mechanism of action of the peptide triazole thiol and its gold nanoparticle conjugates that lead to the virolysis action of HIV-1. In order to study this intriguing breakdown of HIV-1, my studies focused on kinetic and thermodynamic studies. This included understanding the fate of several important viral proteins, including gp120, gp41 and p24, time dependent inhibition of viral entry into host cells and the morphological and biological state of the residual virus. Further the molecular, physical and functional transformations of the gold nanoparticle peptide conjugates and how these properties affect their virolytic function were tested. From these studies it is conclusive that the peptide triazole thiol virolysis event does follow a time-dependent breakdown pathway of the viral machine that eventually leads to complete disruption of the virus. A clear correlation between peptide triazole thiol dependent HIV-1 virolysis and HIV-1 - host cell fusion was observed. Gold nanoparticle peptide triazole conjugate studies showed that the gold nanoparticle inhibitor virolysis works by a different mechanism all together. We further showed that increasing size of the nanoparticle and density of peptide coverage led to an inhibitor with almost 2000 fold enhancement of its anti-viral potency. These studies therefore have led to two major findings; one, the discovery of an innovative class of HIV-1 inhibitors that that lead to complete irreversible breakdown of the virus by hijacking the virus-cell fusion mechanism and two, the proof of concept model of nanoparticle-inhibitor constructs that have opened up the field to the rules required for development of highly potent nanoparticle-inhibitor constructs that irreversibly lyse the virus. These findings have thereby given the HIV-1 field as well as the nanomedicine field an innovative approach that can be further developed and nurtured.Ph.D., Biomedical Engineering -- Drexel University, 201