Negatively charged peptide nanofibrils from immunoglobulin light chain sequester viral particles but lack cell-binding and viral transduction-enhancing properties

Positively charged naturally occurring or engineered peptide nanofibrils (PNF) are effective enhancers of lentiviral and retroviral transduction, an often rate limiting step in gene transfer and gene therapy approaches. These polycationic PNF are thought to bridge the electrostatic repulsions between negatively charged membranes of virions and cells, thereby enhancing virion attachment to and infection of target cells. Here, we analyzed PNF which are formed by the peptide AL1, which represents a fragment of an immunoglobulin light chain that causes systemic AL amyloidosis. We found that negatively charged AL1 PNF interact with viral particles to a comparable extent as positively charged PNF. However, AL1 PNF lacked cell binding activity and consequently did not enhance retroviral infection. These findings show that virion capture and cell binding of PNF are mediated by different mechanisms, offering avenues for the design of advanced PNF with selective functions.