iProXProteomicsLiwen ChenHomo Sapienshttp://www.iprox.org/page/project.html?id=IPX0004120000ay_hhliu@163.comthe second hosptial of anhui medical universityiProXEndoplasmic reticulum aminopeptidase 1 (ERAP1) is a processing enzyme of antigenic peptides presented to major histocompatibility complex (MHC) class I molecules. ERAP1-dependent trimming of epitope repertoire determines an efficacy of adoptive CD8⁺ T-cell responses in several viral diseases; however, its role in hepatitis B virus (HBV) infection remains unknown. Here, we show that the serum level of ERAP1 in patients with chronic hepatitis B (CHB) (<i>n</i> = 128) was significantly higher than that of healthy controls (<i>n</i> = 44) (8.78 ± 1.82 vs. 3.52 ± 1.61, <i>p</i> < 0.001). Furthermore, peripheral ERAP1 level is moderately correlated with HBV DNA level in patients with CHB (<i>r</i> = 0.731, <i>p</i> < 0.001). HBV-transfected HepG2.2.15 cells had substantially increased ERAP1 expression and secretion than the germline HepG2 cells (<i>p</i> < 0.001). The co-culture of ERAP1-specific inhibitor ERAP1-IN-1 pretreated HepG2.2.15 cells or <i>ERAP1</i> knockdown HepG2.2.15 cells with CD8⁺ T cells led to 14-24% inhibition of the proliferation of CD8⁺ T cells. Finally, liquid chromatography tandem mass spectrometry (LC-MS/MS) test demonstrated that ERAP1-IN-1 blocks completely the production of a 9-mers peptide (30-38, LLDTASALY) derived from Hepatitis B core antigen (HBcAg). The predictive analysis by NetMHCpan-4.1 server showed that human leukocyte antigen (HLA)-C*04:01 is a strong binder for the 9-mers peptide in HepG2.2.15 cells. Taken together, our results demonstrated that ERAP1 trims HBcAg to produce 9-mers LLDTASALY peptides for binding onto HLA-C*04:01 in HepG2.2.15 cells, facilitating the potential activation of CD8⁺ T cells.Endoplasmic Reticulum Aminopeptidase 1 Is Involved in Anti-viral Immune Response of Hepatitis B Virus by Trimming Hepatitis B Core Antigen to Generate 9-Mers Peptides.Liu Huanhuan H, Hu Bingqi B, Huang Junfeng J, Wang Qin Q, Wang Feier F, Pan Faming F, Chen Liwen LfalseThe inhibition effect of ERAP1-IN-1 on HepG2.2.15 cellsIn our strudy, we preterated HepG2.2.15 cells with specific ERAP1 inhibitor ERAP1-IN-1(50μM). And then LC-MS/MS analysis was performed on a timsTOF Pro mass spectrometer.Finally we found that among the total peptides identified, ERAP1-IN-1-treated group had an reduction of the numbers of long peptides.Thu Feb 24 00:00:00 GMT 2022PXD031858960635602060