Accounts of chemical research 2017 08 1550(9) 2159-2166 doi 10.1021/acs.accounts.7b00154
Amyloids refer to a class of protein or peptide aggregates that are heterogeneous in size, morphology, and composition, and are implicated to play a central role in many neurodegenerative and systemic diseases. The strong correlation between biological activity and extent of aggregation of amyloidogenic proteins and peptides has led to an explosion of research efforts to target these materials with synthetic molecules or engineered antibodies to try to attenuate their function in disease pathology. Although many of these efforts to attenuate amyloid function have shown great promise in laboratory settings, the vast majority of work has been focused on targeting amyloids associated with neurologic diseases, which has been met with significant additional challenges that preclude clinical evaluation. Only recently have researchers started applying their efforts toward neutralizing the activity of amyloids associated with non-neurologic diseases. For instance, small peptides present in high abundance in human semen have been found to aggregate into amyloid-like fibrils, with in vitro experiments indicating that these amyloid fibrils could potentially increase the rate of infection of pathogens such as HIV by over 400 000-fold during sexual contact. Mechanistic investigations of naturally occurring seminal amyloid species such as Semen-derived Enhancer of Virus Infection (SEVI) and related natural peptide aggregates suggest that these materials interact strongly with virus particles and cell surfaces, facilitating viral attachment and internalization into cells and, thus, possibly promoting sexual transmission of disease. Such amyloid mediators in HIV transmission represent an attractive target for development of chemical approaches to attenuate their biological activity. For instance, the activity of seminal amyloids in genital fluids potentially allows for topical delivery of amyloid-targeting molecules, which could minimize common problems with systemic toxicity or permeability across biological barriers. In addition, molecules that target these amyloid mediators in viral attachment could potentially work synergistically with current antiviral agents to reduce the rate of HIV transmission. This Account will briefly summarize some of the key evidence in support of the capability of SEVI to enhance viral infection, and will highlight examples, many from our group, of recent efforts aimed at inhibiting its activity using synthetic small molecules, oligomeric peptides, and polymeric materials. We present various chemical strategies that have shown promise for neutralizing the role of SEVI in HIV transmission including the development of aggregation inhibitors of SEVI fibril formation, small molecule amyloid binders that modulate the charge or structure of SEVI, and synthetic molecules that form bioresistive coatings on SEVI and inhibit its interaction with the virus or cell surface. We discuss some unique challenges that hamper translation of these molecular strategies toward clinical evaluation, and propose several opportunities for researchers to address these challenges.