(A) Western blots using different mAbs to detect precore/core derivatives in cell lysates that transfected with numerous expressing constructs

(A) Western blots using different mAbs to detect precore/core derivatives in cell lysates that transfected with numerous expressing constructs. enables its applicability in cccDNA-targeting drug testing in cell culture systems and also provides an accurate tool for clinical HBeAg detection. KEYWORDS: Hepatitis B computer virus, Hepatitis B e antigen, monoclonal antibody, cccDNA LPA2 antagonist 1 surrogate, immunoassay Introduction Chronic hepatitis B computer virus (HBV) LPA2 antagonist 1 infection is still a major cause of end-stage liver diseases worldwide including liver cirrhosis (LC) and hepatocellular carcinoma (HCC). According to recent studies, there are more than 290 million people persistently infected with HBV, which results in nearly 1 million deaths annually primarily due to HBV-induced LC and HCC [1, 2]. Chronic HBV contamination usually presents a complex and long-term natural history which is usually characterized by a series of serum and liver markers, including hepatitis B e antigen (HBeAg) status, hepatic inflammation markers (liver enzyme, histologic necroinflammatory scoring) and serum HBV DNA levels [3]. Among these markers, HBeAg is usually non-particulate secretory protein and produced very early in the life cycle of HBV. The HBeAg and hepatitis B core antigen (HBcAg) are two alternate in-frame translation products of HBV precore/core open reading frame (PreC/C ORF). HBcAg is usually a translation product of the core gene alone (183aa for most HBV genotypes) using pregenomic RNA (pgRNA) as its mRNA, which lacks precore AUG at its 5′ end. HBeAg is derived from translation product of the LPA2 antagonist 1 entire precore/core ORF, and the corresponding precore mRNA (pcRNA; slightly longer than pgRNA) has the precore AUG covered at its 5′ end. Of the LPA2 antagonist 1 extra 29aa encoded by the precore region, the first 19aa serve as the transmission peptide targeting the precore/core protein into the secretory pathway [4, 5]. Cleavage of the transmission peptide followed by the arginine-rich C-terminus between residues 149 and 154 by proprotein convertase furin generates mature HBeAg. Therefore, HBeAg has 10 extra residues at its N-terminus (NTR, aa ?10 to ?1, SKLCLGWLWG) than HBcAg but lacks C-terminal 29C34 residues [6, 7]. The 183-aa HBcAg comprises a capsid-forming region called assembly domain name (AD, aa 1C149) and a basic arginine-rich C-terminal domain name (CTD, aa 150C183) for viral DNA and RNA binding [8]. The HBcAg forms the building block of viral capsid LPA2 antagonist 1 which encloses HBV DNA and polymerase, and it also mediates the conversation with inner domain name of viral surface proteins therefore contributing to viral envelopment. Although HBeAg is usually a nonstructural protein, several studies suggested it plays multitude functions in the establishment and progression of chronic HBV contamination by modulating the host immune response [9]. Secreted HBeAg preferentially elicits non-inflammatory Th2 cells and deletes inflammatory Th1 cells by Fas-associated apoptosis [10]. In addition, studies with mouse models have shown that HBeAg plays a role in the impairment Rabbit Polyclonal to BAZ2A of CD8+ cytotoxic T lymphocytes following vertical transmission of HBV [11]. The HBeAg also suppresses the Toll-like receptor (TLR) signalling pathway by interacting with the Toll/interleukin-1 receptor (TIR)-made up of proteins Mal and TRAM and disrupting homotypic TIR to TIR interactions critical for TLR signalling [12]. More recently, HBeAg was also shown to suppress the IFN/JAK/STAT signalling pathway by stimulating the expression of suppressor of cytokine signalling 2 (SOCS2) [13]. As its immune modulating effects, serological HBeAg status is regarded as an important parameter in HBV clinical diagnosis and the immunoassays detecting HBeAg were routinely used in clinical settings for several decades. Serum HBeAg-positive chronic hepatitis B (CHB) patients usually have significantly higher viremia levels, also higher HCC risk than HBeAg-negative patients. HBeAg seroconversion (the loss of serum HBeAg accompanied by the development of anti-HBe antibodies) is considered as an important milestone of favourable end result and good progression of treatment response. Patients who undergo HBeAg seroconversion are more likely to experience improved long-term outcomes, including disease remission, a lower incidence of cirrhosis and HCC, increased rates of survival. Moreover, the recommendation strategies for treatment and follow-up are quite different in most of CHB Clinical Practice Guidelines between HBeAg-positive and -unfavorable patients [3]. Despite the importance of HBeAg as an indication for CHB clinical management, current HBeAg immunoassays are not ideal because the existing ones cross-react with HBcAg, the HBeAg homologue [14]. Because HBeAg shares about 152 aa sequence with HBcAg, most of antibodies used in current HBeAg assays are not completely unreactive with HBcAg [8]. It is generally assumed that this naked HBcAg capsid does not release into bloodstream unless HBV-infected hepatocytes are damaged. Therefor little attention is usually paid to the concern of the Influence of naked HBcAg capsid.