The production of hypochlorous acid (HOCl) is a characteristic of granulocyte activation, a hallmark of the early phase of innate immune responses. In this study, we show that, in addition to its well-established role as a microbicide, HOCl can act as a natural adjuvant of adaptive immunity. HOCl enhances the T cell responses to the model Ag OVA, facilitating the processing and presentation of this protein via the class II MHC pathway. HOCl modification also enhances cross-presentation of the tumor Ag tyrosinase-related protein 2 via class I MHC. The adjuvant effects of HOCl are independent of TLR signaling. The enhanced presentation of HOCl-modified OVA is mediated via modification of the N-linked carbohydrate side chain rather than formation of protein aldehydes or chloramines. HOCl-modified OVA is taken up more efficiently by APCs and is degraded more efficiently by proteinases. Atomic force microscopy demonstrated that enhanced uptake is mediated via specific receptor binding, one candidate for which is the scavenger receptor lectin-like oxidized low-density lipoprotein receptor, which shows enhanced binding to chlorinated OVA. A function of HOCl is therefore to target glycoprotein Ags to scavenger receptors on the APC surface. This additional mechanism linking innate and adaptive immunity suggests novel strategies to enhance immunity to vaccines.

The human coronavirus NL63 is generally classified as a common cold pathogen, though the infection may also result in severe lower respiratory tract diseases, especially in children, patients with underlying disease, and elderly. It has been previously shown that HCoV-NL63 is also one of the most important causes of croup in children. In the current manuscript we developed a set of polymer-based compounds showing prominent anticoronaviral activity. Polymers have been recently considered as promising alternatives to small molecule inhibitors, due to their intrinsic antimicrobial properties and ability to serve as matrices for antimicrobial compounds. Most of the antimicrobial polymers show antibacterial properties, while those with antiviral activity are much less frequent. A cationically modified chitosan derivative, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC), and hydrophobically-modified HTCC were shown to be potent inhibitors of HCoV-NL63 replication. Furthermore, both compounds showed prominent activity against murine hepatitis virus, suggesting broader anticoronaviral activity.

To date, six human coronaviruses have been known, all of which are associated with respiratory infections in humans. With the exception of the highly pathogenic SARS and MERS coronaviruses, human coronaviruses (HCoV-NL63, HCoV-OC43, HCoV-229E, and HCoV-HKU1) circulate worldwide and typically cause the common cold. In most cases, infection with these viruses does not lead to severe disease, although acute infections in infants, the elderly, and immunocompromised patients may progress to severe disease requiring hospitalization. Importantly, no drugs against human coronaviruses exist, and only supportive therapy is available. Previously, we proposed the cationically modified chitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC), and its hydrophobically-modified derivative (HM-HTCC) as potent inhibitors of the coronavirus HCoV-NL63. Here, we show that HTCC inhibits interaction of a virus with its receptor and thus blocks the entry. Further, we demonstrate that HTCC polymers with different degrees of substitution act as effective inhibitors of all low-pathogenic human coronaviruses.

The sequential adsorption of oppositely charged polyelectrolytes called the "layer by layer" technique is a method for formation of ultrathin films with controlled thickness and interfacial properties. Composition of polyelectrolyte solutions, pH, and electrolyte concentration are important parameters governing formation of multilayer films. Since pH is the factor controlling charge of weak polyelectrolytes, the structure of multilayers should be sensitive to its value. In this paper we focused on formation of PE multilayer films composed from weak and strong polyelectrolytes. We used weak, branched polycation polyethyleneimine (PEI, 70 kDa) and strong polyanion poly-4-styrenesulfonate (PSS, 70 kDa) to form films by the layer-by-layer technique on the surface of silicon wafers under two deposition conditions: pH = 6 when PEI was strongly charged and pH = 10.5 when the charge density of PEI was low. Thicknesses of films were measured by single wavelength ellipsometry, and the results were confronted with ones concerning mass of the adsorbed films obtained by quartz crystal microbalance. We found that, depending on pH of the solutions, combination of weakly and strongly charged polyelectrolytes gave either linear or nonmonotonic increase of film thickness with a number of deposited PE layers. We observed a good correlation between multilayer film thickness and adsorbed mass. The atomic force microscopy images of surface topography of PEI/PSS films demonstrated large differences between films deposited at pH = 6 and 10.5. Additionally the cyclic voltamperometry was used to determine the differences in permeability of films formed at various pH conditions.