C-Terminal Amino Acids 471-507 of Avian Hepatitis E Virus Capsid Protein Are Crucial for Binding to Avian and Human Cells

Abstract

The infection of chickens with avian Hepatitis E virus (avian HEV) can be asymptomatic or induces clinical signs characterized by increased mortality and decreased egg production in adult birds. Due to the lack of an efficient cell culture system for avian HEV, the interaction between virus and host cells is still barely understood. In this study, four truncated avian HEV capsid proteins (ORF2-1 – ORF2-4) with an identical 338aa deletion at the N-terminus and gradual deletions from 0, 42, 99 and 136aa at the C-terminus, respectively, were expressed and used to map the possible binding site within avian HEV capsid protein. Results from the binding assay showed that three truncated capsid proteins attached to avian LMH cells, but did not penetrate into cells. However, the shortest construct, ORF2-4, lost the capability of binding to cells suggesting that the presence of amino acids 471 to 507 of the capsid protein is crucial for the attachment. The construct ORF2-3 (aa339-507) was used to study the potential binding of avian HEV capsid protein to human and other avian species. It could be demonstrated that ORF2-3 was capable of binding to QT-35 cells from Japanese quail and human HepG2 cells but failed to bind to P815 cells. Additionally, chicken serum raised against ORF2-3 successfully blocked the binding to LMH cells. Treatment with heparin sodium salt or sodium chlorate significantly reduced binding of ORF2-3 to LMH cells. However, heparinase II treatment of LMH cells had no effect on binding of the ORF2-3 construct, suggesting a possible distinct attachment mechanism of avian as compared to human HEV. For the first time, interactions between avian HEV capsid protein and host cells were investigated demonstrating that aa471 to 507 of the capsid protein are needed to facilitate interaction with different kind of cells from different species.

Avian Hepatitis E Virus: With the Trend of Genotypes and Host Expansion

“…In addition to viral replication, virus attachment to host cells is considered to be another crucial step in viral infections (Schneider-Schaulies, 2000; Yugo et al, 2016). It is reported that the capsid protein region from amino acid 471 to 507 is critical for avian HEV attachment to host cells (Zhang et al, 2016) and the C-terminal region of the capsid ORF2 protein is recognized as putative binding sites for both cellular receptors and neutralizing antibodies (Ahmad et al, 2011). Wang et al (2018) utilized Lactococcuslactis as a delivery vector expressing higher levels of ΔORF2 (avian HEV truncated ORF2 protein spanning amino acids 249–606 protein) specific IgG antibodies, in order to neutralize or bind to avian HEV and induce effective mucosal immunity, prevented the virus from invading into host cells.…”

Chicken Organic Anion-Transporting Polypeptide 1A2, a Novel Avian Hepatitis E Virus (HEV) ORF2-Interacting Protein, Is Involved in Avian HEV Infection

“…ap237 attachment to different cell lines. In a previous study, it was documented that ap237 can imitate natural avian HEV particles and attach to LMH cells (30). In this study, the variations of ap237 attachment to differently treated LMH cell lines expressing different levels of OATP1A2 were first analyzed.…”

“…This region corresponded with the amino acid region of the human HEV p239 protein. In some previous studies, the results showed that ap237 contains most of the antigenic epitopes of avian HEV (18)(19)(20) and the key domain (aa 471 to 507) for binding to LMH cells (30) derived from chicken hepatocellular carcinoma epithelial cells (31), which support avian HEV replication (32). Next, ap237 was employed as a bait protein to target the host factors in chicken liver tissue.…”

“…OATP1A2 Is Involved in Avian HEV Infection Journal of Virology OATP1A2 enhances ap237 attachment to LMH cells. A previous study showed that ap237 can mimic natural avian HEV attachment to host cells (30). In this study, ap237 was used to analyze the relationship between ap237 attachment and the expression of OATP1A2 in cells.…”

Distribution and molecular characterization of avian hepatitis E virus (aHEV) in domestic and wild birds in Burkina Faso

“…Phylogenetic analysis of the full or nearly complete genome of aHEV strains identified four different genotypes and showed a distant relationship to mammalian and swine HEVs (50 to 60% nucleotide sequence identity) (Smith et al, 2015). The aHEV genotype 1 has been described in Australia and Korea, genotype 2 in USA, genotype 3 in Europe and China, and more recently, genotype 4 in Hungary and Taiwan (Payne et al, 1999;Park et al, 2015;Wang et al, 2015;Moon et al, 2016;Zhang et al, 2016).…”