CHALLENGES AND RECENT DEVELOPMENTS ASSOCIATED WITH VACCINE ANTIGENS PRODUCTION AGAINST HELICOBACTER PYLORI

Around half of the world’s population faces Helicobactor pylori (H. pylori) infection. Enormous progress has been made to understand the bacterial pathogenesis process and pathogen interaction with eukaryotic cells but infectious diseases are still the cause of premature death of humans around the world. H. pylori is categorized under class I carcinogen by the WHO based on clinical study results. This review paper discusses various attempts made to establish an efficient vaccine to manage H. pylori infection. Some of the problems in developing an efficient vaccine against H. pylori are recurrent or persistent infection, insufficient knowledge about the action specifically in case of probiotics, development of antibiotic resistance, and cost of therapy are noted. This research may come up with transient Nicotiana benthamiana with suitable H. pylori genes expressed as antigenic proteins, which can be used for further studies to develop a vaccine for gastric ulcer/cancer and generate good scientific data that can be helpful for scientists and researchers in this field. This review article for monitors’ current approaches monitoring H. pylori infection since 1998 to 2019 using world-wide recognized journals and books, questioning its efficacies and whether these strategies help eradicate or there is a need to focus on several diversions. We provide scientific recommendations in eliminating H. pylori through vaccination along with addressing the preventive vaccine for this pathogen rather than using defeated treatments with plant-based nil side effects solution. The information relies on the available content in Google Scholar and PubMed using the keywords listed below

Sulfated Polysaccharide, Curdlan Sulfate, Efficiently Prevents Entry/Fusion and Restricts Antibody-Dependent Enhancement of Dengue Virus Infection In Vitro: A Possible Candidate for Clinical Application

10.1371/journal.pntd.0002188PLoS Neglected Tropical Diseases74

Proposed binding model of CRDS to DENV envelope protein obtained by Induced fit docking.

<p>The coordinates of the DENV E protein were obtained from PDB from the crystal structure 1OKE <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002188#pntd.0002188-Modis1" target="_blank">[13]</a>. Detailed information is described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002188#s2" target="_blank">Materials and Methods</a>.</p

Effect of CRDS on low pH-induced fusion of DENV-2 infected C6/36 cells.

<p>The cells were incubated with DENV at 4°C for 1.5 h during viral adsorption in the presence of 100 µg/mL of either CRDS or heparin, followed by a temperature shift to 28°C, and cultured for 4 days to monitor virus-induced cell fusion (A). In the experiment shown in B, the compound was added at the time of temperature shift to 28°C, after viral attachment.</p

Antiviral activity of CRDS on the four dengue virus serotypes.

<p>Antiviral activity of CRDS on the four dengue virus serotypes.</p

CRDS inhibits both attachment as well as an early post-attachment step of entry.

<p>Time of addition experiments were performed to identify the step at which CRDS exerts its effect (A) and efficacy of inhibitors during attachment and post-attachment (B). Studies were performed using the LLC-MK2 cells as described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002188#s2" target="_blank">Materials and Methods</a> in detail.</p

Hydrogen bonding interactions of the inhibitor with the residues in the binding pocket.

<p>Strong H-bonds (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002188#pntd-0002188-t003" target="_blank">Table 3</a>) are formed with conserved residues His 244, Lys 310, Asn 153 and Lys 247 (A). Residues lining the CRDS-binding pocket of the E protein (B).</p

LigPlot⁺ representation of the hydrophobic interactions between CRDS and the residues of the binding pocket.

<p>The hydrophobic contacts are represented by dotted lines. The LigPlot⁺<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002188#pntd.0002188-Laskowski1" target="_blank">[49]</a> was used to map the interactions.</p

Effect of CRDS on DENV-2 infection in DC-SIGN-expressing cells.

<p>The effect of CRDS was evaluated on DENV infection in DC-SIGN expressing cells. Raji-DC-SIGN cells were infected with large amount of DENV (1000 pfu) in the presence of CRDS. The cultures were analyzed for DENV infection by FACS assays 4 days later.</p

Chemical structure of CRDS and antiviral activity based on DENV-2 MTT assay using LLC-MK2 cells.

<p>Structure of CRDS (A) and dose-dependent inhibition of DENV-2 infection by CRDS by MTT assay (B).</p