RNA transcription was performed using T7 RiboMAX Express Good sized Scale RNA Creation Program (Promega). antibody. Either low-density lipoprotein or HDL escalates the creation and infectivity of cell culture-produced HCV, but E1 preferentially selects HDL, influencing both viral life cycle and antibody evasion. IMPORTANCE Hepatitis C virus (HCV) infection is a significant burden on human health, but vaccine candidates have yet to provide broad protection against this infection. We have developed a method to produce high quantities of soluble E1 or E2, the viral proteins located on the surface of HCV. HCV has an unusually high lipid content due to the recruitment of apolipoproteins. We found Rabbit polyclonal to SHP-1.The protein encoded by this gene is a member of the protein tyrosine phosphatase (PTP) family. that E1 (and not E2) preferentially recruits host high-density lipoprotein (HDL) extracellularly. This recruitment of HDL by E1 prevents binding of E1 by a neutralizing antibody and furthermore prevents antibody-mediated neutralization of the virus. By comparison, low-density lipoprotein does not protect the virus from antibody-mediated neutralization. Our findings provide mechanistic insight into apolipoprotein recruitment, which may be critical for vaccine development. KEYWORDS: hepatitis C virus, envelope glycoprotein 1, high-density lipoprotein, apolipoproteins INTRODUCTION Hepatitis C virus (HCV) is a leading cause of liver-related morbidity and mortality, and new infections are increasing in the USA in conjunction with increased intravenous drug abuse (1). Currently, there are about 58 million chronically infected people worldwide (2). Eventually, chronic HCV infection can lead to complications such as fibrosis, cirrhosis, and hepatocellular carcinoma (3). Direct-acting antivirals are curative but unlikely to clear the population because clinical signs of HCV infection can go undetected for decades, and access is limited. A prophylactic vaccine is critical for HCV eradication, but candidates to date have been ineffective (4). HCV is a member of the family; of the 10 mature proteins encoded by its single-stranded, positive sense RNA genome, there are two envelope glycoproteins, E1 and E2. E1 and E2 form a heterodimer to mediate cellular attachment and facilitate membrane fusion during entry (5). E2 specifically UAA crosslinker 2 recognizes two cellular entry factors, CD81 and scavenger receptor class B type I (SR-BI), and is the target of many neutralizing antibodies. The functions of E1 have not been clearly defined, but E1 has been proposed to modulate E2 folding, assist in fusion, and bind other cellular factors to mediate UAA crosslinker 2 entry (6,C8). The study of E1 protein has been difficult due, in part, to the inability to produce soluble, properly folded, and functional protein independent of E2 (9,C11). The characterization UAA crosslinker 2 of E1 has been further hindered by the limited number of E1-specific antibodies (9, 11). Currently, only two neutralizing immunogenic regions have been identified: region 313C327, which is recognized by cross-reactive and cross-neutralizing antibodies IGH-526 and IGH-505, and region 192C211, which is recognized by neutralizing antibody H-111 (12, 13). Monoclonal antibody (MAb) IGH-526 was derived from a human donor who had cleared HCV infection after interferon-based therapy; neutralizes HCV pseudoparticles (HCVpp) from genotypes 1a, 1b, 4a, 5a, and 6a and cell UAA crosslinker 2 culture HCV (HCVcc) from genotypes 1a and 2a; and binds to a discontinuous, highly flexible epitope that adopts a 2.5-turn -helix (14). H-114 is a patient-derived, non-neutralizing antibody that recognizes an unknown conformational epitope (15). Although anti-E1 antibodies are few and frequently non-neutralizing, immunization with E1 and E2 as separate immunogens increases cross-neutralization, which emphasizes the role of E1 in viral clearance and its potential as a vaccine candidate (16). A defining feature of the HCV virion is its remarkably low-buoyant density, making it more similar in.