Inhibition of the Enhancement of Infection of Human Immunodeficiency Virus by Semen-Derived Enhancer of Virus Infection Using Amyloid-Targeting Polymeric Nanoparticles

Abstract

The semen-derived enhancer of virus infection (SEVI) is natural amyloid material that has been shown to substantially increase viral attachment and infectivity of HIV in cells. We previously reported that synthetic monomeric and oligomeric amyloid-targeting molecules could form protein-resistive coatings on SEVI and inhibit SEVI- and semen-mediated enhancement of HIV infectivity. While oligomeric amyloid-binding compounds showed substantial improvement in apparent binding to SEVI compared to monomeric compounds, we observed only a modest correlation between apparent binding to SEVI and activity for reducing SEVI-mediated HIV infection. Here, we synthesized amyloid-binding polyacrylate-based polymers and polymeric nanoparticles of comparable size to HIV virus particles (~150 nm) to assess the effect of sterics on the inhibition of SEVI-mediated enhancement of HIV infectivity. We show that these polymeric materials exhibit excellent capability to reduce SEVI-mediated enhancement of HIV infection, with the nanoparticles exhibiting the greatest activity (IC50 value of ~4 μg/mL, or 59 nM based on polymer) of any SEVI-neutralizing agent reported to date. The results support that the improved activity of these nanomaterials is likely due to their increased size (diameters = 80-200 nm) compared to amyloid-targeting small molecules, and that steric interactions may play as important a role as binding affinity in inhibiting viral infection mediated by SEVI amyloids. In contrast to the previously reported SEVI neutralizing, amyloid-targeting molecules (which required concentrations at least 100-fold above the Kd to observe activity), the approximate 1:1 ratio of apparent Kd to IC50 for activity of these polymeric materials, suggests the majority of polymer molecules that are bound to SEVI contribute to the inhibition of HIV infectivity enhanced by SEVI. Such size-related effects on physical inhibition of protein-protein interactions may open further opportunities for the use of targeted nanomaterials in disease intervention.

Hydrophobic Nanoparticles Reduce the β-Sheet Content of SEVI Amyloid Fibrils and Inhibit SEVI-Enhanced HIV Infectivity

“…Using polymer 4, we generated spherical NPs with an average diameter of 265 nm in solution and average polydispersity of 0.16, using a previously described solvent evaporation technique (Table 1 and Figure S2). 22,41,42 Although this technique made it possible to reproducibly generate NPs with a similar size (±37 nm over 5 preparations), other methods for NP preparation 43−45 could potentially be explored to predictably generate a set of NPs with a range of different diameters.…”

“…As a control hydrophilic polymer, we also synthesized a previously reported PHONA (5) polymer containing 100% monomethyl hydroxyethylene glycol side chains in ∼45% yield using the same free-radical polymerization procedure used to generate polymer 4 (Scheme 1, Table 1, and Figure S1B). 22 We analyzed the effects of polymer 5 in subsequent SEVI structure and function assays without further changes to its formulation, as the high solubility of this polymer in aqueous solutions precluded the possibility for its conversion to stable NPs.…”

Semen‐derived amyloidogenic peptides—Key players of HIV infection

“…Nanoparticles, which were generated from a polymer comprising moieties of amyloid‐binding 6‐methylbenzothiazole aniline with high affinity for SEVI amyloid fibrils and similar in size and shape to HIV virions, disabled SEVI‐mediated HIV transmission in cells . These nanoparticles and polymers were far more efficient for inhibiting SEVI‐enhanced HIV infection than monomeric and pentameric 6‐methylbenzothiazole aniline, proposing a critical role of steric hindrance in the design of effective SEVI neutralizing agents.…”

“…50 Nanoparticles, which were generated from a polymer comprising moieties of amyloid-binding 6methylbenzothiazole aniline with high affinity for SEVI amyloid fibrils and similar in size and shape to HIV virions, disabled SEVI-mediated HIV transmission in cells. 51 These nanoparticles and polymers were far more efficient for inhibiting SEVI-enhanced HIV infection than monomeric and pentameric 6methylbenzothiazole aniline, proposing a critical role of steric hindrance in the design of effective SEVI neutralizing agents. A very recent study suggested that a nanoparticle formulation of hydrophobic polymers diminished SEVI amyloid-mediated HIV 31 infection, and that the use of hydrophobic interactions to alter structures of amyloid fibrils at the level of the secondary structures may be an useful approach to neutralize the SEVI function.…”

Natural product-based nanomedicine: recent advances and issues

“…Polyacrylate-based nanoparticles functionalized with BTA were used to impede semen-derived enhancer of virus infection mediation in HIV-infected cells. 113 Certain natural compounds, such as curcumin, have demonstrated anti-Alzheimer properties. 117 The BTA-based nanoparticle described above could potentially be modified to improve the delivery of these natural compounds for betterquality treatment of Alzheimer's disease.…”