|
Computational analysis suggests that transmission of the Nipah virus can be significantly reduced if a cavity identified in a model of the trimeric fusion protein is filled by a complementary molecule. Because this cavity is hydrophobic, we hypothesized that small, bivalent, non-peptide compounds would have the greatest success in the inhibition of cell entry by the virus. This observation is based on the ability of appropriate small molecules to adhere tightly to the binding pocket of the related measles virus, and knowledge that non-peptides are not easily degraded by enzymes carried by the body’s blood. Since no effective blockers are known, computational protein homology modeling was combined with synthetic chemistry. Although ten novel compounds were developed only four were tested for bioactivity.
• Nipah virus (NV) is a highly infectious, fatal pathogen that is a potential weapon for bioterroists
• NV is characterized as a paramyxovirus – an enveloped negative-stranded RNA virus
• Much of what we know about NV is based on Measles Virus and the Newcastle Disease Virus (similar paramyxoviruses; the latter in English chickens)
• Common to all enveloped viruses is the necessity that fusion occur between the host-cell plasma membrane and the viral membrane in order for the viral genome to be inserted into the cell[i]
• Fusion is regulated by neuraminidase glycoprotein (N) and glycosylated fusion protein (F), which is a trimeric, cone-shaped molecule with a hydrophobic cavity
• We hypothesized that small, bivalent, non-peptide compounds would be most effective in the development of novel Nipah virus fusion inhibitors
• The biological activity of the synthesized compounds would be tested with a protein assay similar to that used for the Measles Virus and a homology model constructed from the New Castle Disease virus
Preparation of Nipah Virus Non-Peptide Antagonists
Synthesis of Potential Fusion Inhibitor
Model of Protein Binding
Purification
Nuclear Magnetic Resonance (NMR)
1H and 13C used to verify structure and purity of compounds
Ten compounds were designed and prepared in accord with the Nipah virus homology model. Four of these tested in a Nipah fusion protein model were inactive. Complementary bioassays against measles virus were also carried out; below.
Table 1: Protein assay results for the compounds tested in Measles Virus Edmonston (Laboratory Strain) and Measles Virus Kansas (patient strain)
Chart 1: Bioactivity of Compounds in different measles virus strains
• NMR confirmed the structure of the synthesized compounds. Purity was also determined from this data.
• Protein Assay results suggest there is no biological activity for the tested compounds either in measles or Nipah virus models.
• Limitations of this data are that there is no full scale X-ray model for the Nipah Virus, and the protein assay for Nipah is not yet fully validated.
• Future directions include refining the homology model specifically for the Nipah Virus.
• Additionally, more potential compounds will be synthesized and tested.
Dr. James P. Synder, my mentor; Dr. Dennis Liotta for opening his laboratory to me; Weiqiang Zhan, an Emory Chemistry Department Graduate Student; Dr. Richard Plemper for testing my compounds in the Nipah Virus Assay
Funding: This material is based upon work supported by the Howard Hughes Medical Institute under Grant No.52003727 and by my mentor, Dr. James Snyder.
Viruses require a host cell in order to proliferate because they do not have their own cell making machinery. This integral stage in the life cycle of a virus is referred to as fusion. The goal of my research was to develop new compounds that would prevent fusion between the virus and host cell from occurring. The development for these compounds was based on molecular models of the fusion-binding pocket. Our models suggested that small, bivalent, non-peptide compounds would work best at inhibiting fusion.
Column Chromatography, NMR, synthesis
Synthesis, Nipha virus, fusion inhibitors, protein assay
|
