Defensins in Viral Infections

Abstract

Defensins are antimicrobial peptides important to innate host defense. In addition to their direct antimicrobial effect, defensins modulate immune responses. Increasing evidence indicates that defensins exhibit complex functions by positively or negatively modulating infections of both enveloped and non-enveloped viruses. The effects of defensins on viral infections appear to be specific to the defensin, virus and target cell. Regulation of viral infection by defensins is achieved by multiple mechanisms. This review focuses on the interplay between defensins and viral infections, the mechanisms of action of defensins and the in vivo studies of the role of defensins in viral infections.

Human Alpha-Defensin HNP1 Increases HIV Traversal of the Epithelial Barrier: A Potential Role in STI-Mediated Enhancement of HIV Transmission

“…The results represent means of a minimum of three representative fields for each experiment and averages of two independent experiments as described by Galvin and Cohen (11). activity of HNP1 in vitro is well established (8), its association with an increased risk of HIV acquisition is not clear. This study found that HNP1 increased epithelial permeability and disrupted tight junctions, facilitating HIV traversal of polarized colorectal epithelial cells.…”

“…These defensins are believed to play a role in controlling bacterial infection. However, increasing evidence indicates that defensins could exhibit pleotropic effects on viral infection (8,34). HD5 contributes to Neisseria gonorrhoeae-mediated enhancement of HIV infectivity in vitro (18,29), whereas HNPs block HIV infection in vitro through multiple mechanisms (7,22,33).…”

Functional Determinants of Human Enteric α-Defensin HD5

“…These small, 2-5-kDa peptides are classified into ␣, ␤, and families based on sequence homology and the connectivity of disulfide bonds linking the six conserved cysteine residues (6,7). Defensins bind carbohydrates (8,9), lipids (10,11), and DNA (12) and are active against a wide range of microorganisms, including bacteria (13,14) and viruses (15)(16)(17). Defensins are also capable of interacting with an diverse array of cellular receptors and host proteins, playing important immunomodulatory functions (5,18).…”

The Cells of Innate Systems in Tick-Borne Encephalitis

“…In addition to their direct antimicrobial effect, defensins modulate immune responses. Increasing evidence indicates that defensins exhibit complex functions by positively or negatively modulating infections of both enveloped and non-enveloped viruses (Ding et al, 2009). The effects of defensins on viral infections appear to be specific to the defensin, virus and target cell.…”

“…The inhibition of its cell function can partially suppress of organism immune response. Recent evidence indicates that defensins modulate viral infection through multiple mechanisms (Ding et al, 2009). …”