Virus infections pose significant global health challenges, especially in view of the fact that the emergence of resistant viral strains and the adverse side effects associated with prolonged use continue to slow down the application of effective antiviral therapies. This makes imperative the need for the development of safe and potent alternatives to conventional antiviral drugs. In the present scenario, nanoscale materials have emerged as novel antiviral agents for the possibilities offered by their unique chemical and physical properties. Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses including human imunodeficiency virus, hepatitis B virus, herpes simplex virus, respiratory syncytial virus, and monkey pox virus. The use of metal nanoparticles provides an interesting opportunity for novel antiviral therapies. Since metals may attack a broad range of targets in the virus there is a lower possibility to develop resistance as compared to conventional antivirals. The present review focuses on the development of methods for the production of silver nanoparticles and on their use as antiviral therapeutics against pathogenic viruses.

Gram negative bacteria have evolved many mechanisms of attaching to and invading host epithelial and immune cells. In particular, many outer membrane proteins (OMPs) are involved in this initial interaction between the pathogen and their host. The outer membrane (OM) of Gram-negative bacteria performs the crucial role of providing an extra layer of protection to the organism without compromising the exchange of material required for sustaining life. The OM, therefore, represents a sophisticated macromolecular assembly, whose complexity has yet to be fully elucidated. This review will summarize the structural information available for porins, a class of OMP, and highlight their role in bacterial pathogenesis and their potential as therapeutic targets.The functional role of porins in microbe-host interactions during various bacterial infections has emerged only during the last few decades, and their interaction with a variety of host tissues for adhesion to and invasion of the cell and for evasion of host-defense mechanisms have placed bacterial porins at the forefront of research in bacterial pathogenesis. This review will discuss the role that porins play in activating immunological responses, in inducing signaling pathways and their influence on antibiotic resistance mechanisms that involve modifications of the properties of the OM lipid barrier.

Human beta-defensins (hBDs) are antimicrobial peptides of human innate immunity. The antibacterial activities of hBDs 1, 2, and 4 but not the activity of hBD3 are impaired by high salt levels. We have designed and synthesized seven novel hBD analogs, constituted by different domains of hBD1 (which is constitutively expressed in humans) and of hBD3 (which is induced by microorganisms and inflammatory factors in humans), that would maintain and potentially increase the wild-type antimicrobial activities and be salt resistant. We have compared the antibacterial, antiviral, and chemotactic activities of the analogs with those of hBD1 and hBD3. We show that the hBD1 internal region and the hBD3 C-terminal region are critical for antibacterial activity also at high salt concentrations, whereas deletion of the N-terminal region of hBD3 results in an increase in antibacterial activity. All analogs inhibited herpes simplex virus; antiviral activity was enhanced by the hBD1 internal region and the hBD3 C-terminal region. Wild-type and analog peptides were chemotactic for granulocytes and monocytes, irrespective of the salt concentrations. These new peptides may have therapeutic potential.

No abstract