Identification and Characterization of Peptides That Interact with Hepatitis B Virus via the Putative Receptor Binding Site

Abstract

A direct involvement of the PreS domain of the hepatitis B virus (HBV) large envelope protein, and in particular amino acid residues 21 to 47, in virus attachment to hepatocytes has been suggested by many previous studies. Several PreS-interacting proteins have been identified. However, they share few common sequence motifs, and a bona fide cellular receptor for HBV remains elusive. In this study, we aimed to identify PreS-interacting motifs and to search for novel HBV-interacting proteins and the long-sought receptor. PreS fusion proteins were used as baits to screen a phage display library of random peptides. A group of PreS-binding peptides were obtained. These peptides could bind to amino acids 21 to 47 of PreS1 and shared a linear motif (W 1 T 2 X 3 W 4 W 5 ) sufficient for binding specifically to PreS and viral particles. Several human proteins with such a motif were identified through BLAST search. Analysis of their biochemical and structural properties suggested that lipoprotein lipase (LPL), a key enzyme in lipoprotein metabolism, might interact with PreS and HBV particles. The interaction of HBV with LPL was demonstrated by in vitro binding, virus capture, and cell attachment assays. These findings suggest that LPL may play a role in the initiation of HBV infection. Identification of peptides and protein ligands corresponding to LPL that bind to the HBV envelope will offer new therapeutic strategies against HBV infection.Attachment of virions to human hepatocyte membrane via the interaction of the viral envelope protein with a specific cell surface receptor is considered the initial step of hepatitis B virus (HBV) infection. Besides host-derived phospholipids, the envelope of an HBV virion contains virus-derived small (SHBs), middle (MHBs), and large (LHBs) surface proteins translated from distinct initiation codons while sharing a common carboxyl domain (i.e., SHBs). Consequently, LHBs contains an extra N-terminal PreS domain, which is further divided into the amino-PreS1 and carboxyl-PreS2 domains. MHBs contains the PreS2 domain but lacks the PreS1 domain. LHBs is associated mainly with infectious virions but can also be found in smaller amounts on rod-shaped subviral particles. On the other hand, the spherical subviral particles are composed mainly of SHBs. LHBs plays a pivotal role in the infection and budding stages of the HBV life cycle. LHBs proteins in the virion envelope exhibit mixed topologies, with their PreS domains protruding either inwardly or outwardly (32,35

Structural basis for the neutralization of hepatitis E virus by a cross-genotype antibody

“…Hepatitis E is transmitted primarily via the fecal-oral route [2] and is caused by HEV, a small non-enveloped, positive-sense, single-stranded RNA icosahedral virus, of the genus Hepevirus [3]. The infection-to-mortality ratio of HEV is small; however, this significantly increases in infants under the age of 2 years, in pregnant women, and in adults over the age of 56 years (5%-25%) [4][5][6]. Four major genotypes of HEV have been identified to date, with a single serotype: genotypes 1 and 2 are human viruses that circulate only in humans as an epidemic form, whereas genotypes 3 and 4 are zoonotic, swine viruses that infect a wide range of mammalian species as well as humans in sporadic cases [1,7].…”

Deciphering the mystery of hepatitis B virus receptors: A historical perspective

“…Deng and colleagues identified that preS1 binding motif is W/FT/ SXWW/F where X can be any amino acid. Through BLAST search and molecular modeling studies, they have identified that this binding motif is present in carboxy terminal domain (amino acid 313-448) of LPL [10]. It has been reported that synthesis of LPL is done in extrahepatic tissues [38].…”

“…LPL is distributed throughout the body, present on many cells of body despite of hepatocytes. HBV can only interact to those cells that express LPL [10].…”

“…The primary target organ of HBV is hepatocytes, and all of receptors reported so far are not hepatocyte specific as P80 expresses not only in hepatocytes but also in all human tissues [56], HBV-BF is soluble receptor [8], IL6 also expresses on hepatic as well as on cells of non-hepatic origin [48], heparin sulfate is also not a specific hepatic receptor it expresses on many different cells [57], lipoprotein lipase is also not a liver specific receptor [10]. Although studies have reported that these receptors have binding motif for preS1 region of HBV but none of the study elaborating the post binding events.…”

“…Although different studies targeting the area of research lead to identification of more than ten different HBV preS1 interacting proteins, until recently, NTCP gained the privilege of stating to be the bona fide receptor of HBV. Most of the candidate receptor's tried, have underlying molecular and cellular interactions, largely unknown [10].…”