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The major pathological feature of Alzheimer’s disease (AD) is the aggregation of amyloid β peptide (Aβ) in the brain. Inhibition of Aβ42 aggregation may prevent the advancement of AD. This study employed molecular dynamics, molecular docking, electron microscopy, circular dichroism, staining of aggregated Aβ with ThT, cell viability, and flow cytometry for the detection of reactive oxygen species (ROS) and apoptosis. Aβ42 polymerizes into fibrils due to hydrophobic interactions to minimize free energy, adopting a β-strand structure and forming three hydrophobic areas. Eight dipeptides were screened by molecular docking from a structural database of 20 L-α-amino acids, and the docking was validated by molecular dynamics (MD) analysis of binding stability and interaction potential energy. Among the dipeptides, arginine dipeptide (RR) inhibited Aβ42 aggregation the most. The ThT assay and EM revealed that RR reduced Aβ42 aggregation, whereas the circular dichroism spectroscopy analysis showed a 62.8% decrease in β-sheet conformation and a 39.3% increase in random coiling of Aβ42 in the presence of RR. RR also significantly reduced the toxicity of Aβ42 secreted by SH-SY5Y cells, including cell death, ROS production, and apoptosis. The formation of three hydrophobic regions and polymerization of Aβ42 reduced the Gibbs free energy, and RR was the most effective dipeptide at interfering with polymerization.

Yechun Pei,1– 3,* Zhengpan Xiao,1,2,* Shuangshuang Wei,1,2 Meiqi Peng,1,2 Chenghui Luo,1,2 Dayong Wang2,3 1School of Life Sciences, Hainan University, Haikou, People’s Republic of China; 2Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou, People’s Republic of China; 3One Health Institute, Hainan University, Haikou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yechun Pei, Department of Biosciences, School of Life Sciences, Hainan University, 58 People’s Road, Haikou, Hainan, 570228, People’s Republic of China, Email ycpei@hainanu.edu.cn Dayong Wang, Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, 58 People’s Road, Haikou, Hainan, 570228, People’s Republic of China, Email wangdy@hainanu.edu.cnBackground: In tropical and subtropical areas, allergens from the dust mite species Blomia tropicalis are common causes of allergic rhinitis and asthma. Blomia tropicalis has two main allergens: Blo t 5 and Blo t 21.Aim: To generate a chimeric virus-like particle containing HBcAg, Blo t 5 and Blo t 21 that can treat allergies caused by Blomia tropicalis.Methods: To produce allergic asthma in mice, prokaryotic expression and purification of Blomia tropicalis allergens rBlo t 5, rBlo t 21, and recombinant fusion allergen rBlo t 5– 21 were utilized in the study. We created a hepatitis B core antigen (HBcAg) and rBlo t 5– 21 fusion prokaryotic expression plasmid. HBcAg-rBlo t 5– 21 was purified after expression and tested by transmission electron microscopy (TEM). Furthermore, the protein HBcAg-rBlo t 5– 21 was employed as a protein vaccination.Results: In allergy-induced mouse model experiments, the fusion allergen rBlo t 5– 21 was more effective than the individual allergens rBlo t 5 and rBlo t 21 at inducing allergy. We found that vaccinating allergic mice with the recombinant fusion protein vaccine HBcAg-rBlo t 5– 21 alleviated allergy symptoms elicited by the rBlo t 5– 21 allergen. Vaccination with HBcAg-rBlo t 5– 21 resulted in a decrease in total serum IgE levels, suppression of anaphylaxis, and reduction of inflammatory cell infiltration into lung tissue as compared to the PBS group.Conclusion: HBcAg-rBlo t 5– 21, a protein vaccine containing both the hepatitis B core antigen and the Blomia tropicalis fusion allergen rBlo t 5– 21, could be a suitable vaccination for preventing allergy disorders caused by Blomia tropicalis.Keywords: Blomia tropicalis, vaccine, hepatitis B core antigen, asthma