# Multipotent Antiviral Effects of Deacetylated Chitosan
## 4 Discussion
The present study demonstrated that supplementing deacetylated chitosan with GSE may be important for enhancing the natural antiviral properties of chitosan. Chitosan, with an 85% deacetylation degree, has demonstrated antiviral potential in human A549 lung cancer cells, reducing viral protein levels and gene expression in both H1N1- and HPIV3-infected cells in a deacetylation-dependent manner. In addition, chitosan with a high degree of deacetylation inhibited the HPIV3-induced p38 MAPK pathway and mitochondrial fragmentation in A549 lung cancer cells. Previously, chitosan oligosaccharidesacharidewas found to influence the regulation of several cellular signaling pathways, including NFxB and MAPK [40; 41]. Interestingly, a study showed that the expression levels of TNF-alpha and IFN-beta increased significantly, suggesting that the antiviral activity of amino-modified chitosan operates by stimulating the immune response [42]. Deacetylated chitosan may exert its antiviral effects by inhibiting p38 MAPK phosphorylation and preserving mitochondrial integrity in virus-infected A549 cells. These studies indicate that chitosan can inhibit inflammation by modulating cellular stress signaling, corroborating our findings. However, further studies are needed to verify whether chitosan exhibits antiviral or anti-inflammatory effects in vivo based on the degree of deacetylation or combination with GSE. Using MDCK and A549 cells, we demonstrated the antiviral effects of deacetylated chitosan with GSE against H1N1 and HPIV3 in vitro. Chitosan is a nontoxic biopolymer with a broad range of applications, including antimicrobial products. After treatment with deacetylated chitosan and GSE, the viability of MDCK and A549 cells showed no significant cytotoxicity for the five tested combinations. This study highlights the importance of the degree of chitosan deacetylation and its antiviral effects in vitro. Moreover, we confirmed the therapeutic potential of deacetylated chitosan against influenza epidemics. Interestingly, an in vivo study on chitosan implied that efficient mucosal vaccine delivery could be achieved using chitosan and its derivative, trimethyl chitosan nanoparticles, which are readily absorbed by microfold cells in nasal-associated lymphoid tissues and dendritic cells [43]. Recently, interesting findings on chitosan involving various nanoparticles have been reported. Zinc-stabilized chitosan-chondroitin sulfate nanocomposites have shown potential as drug delivery systems to enhance antiviral efficacy in the treatment of HIV-1 infection by inhibiting viral reservoirs [44]. Silver nanoparticle-chitosan composites have also been developed, displaying size-dependent antiviral activity against the H1N1 influenza A virus, with smaller nanoparticles yielding stronger antiviral effects [45]. Acyclovir-loaded chitosan nanospheres generated via a nanoemulsion template showed enhanced antiviral activity against herpes simplex virus compared to free acyclovir, making them useful for the topical treatment of herpes virus infections [46]. Acyclovir-loaded chitosan nanospheres showed improved antiviral efficiency against herpes simplex virus compared to free acyclovir, emphasizing their potential as topical therapies against herpes virus infections [46]. Various chitosan sources and preparation methods allow the production of a wide range of chitosan polymers with distinct physicochemical properties, including degree of deacetylation, MW, crystallinity, residual ash, and protein content [37]. Consequently, research on nanoparticle applications and composite materials is helpful.