Expression and characterization of myristoylated preS1-conjugated nanocages for targeted cell delivery

Hepatitis B virus pre-S region: Clinical implications and applications

Hepatitis B virus (HBV) infection is a major threat to global public health, which can result in many acute and chronic liver diseases. HBV, a member of the family Hepadnaviridae, is a small enveloped DNA virus containing a circular genome of 3.2 kb. Located upstream of the S-open-reading frame of the HBV genome is the pre-S region, which is vital to the viral life cycle. The pre-S region has high variability and many mutations in the pre-S region are associated with several liver diseases, such as fulminant hepatitis (FH), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). In addition, the pre-S region has been applied in the development of several pre-S-based materials and systems to prevent or treat HBV infection. In conclusion, the pre-S region plays an essential role in the occurrence, diagnosis, and treatment of HBV-related liver diseases, which may provide a novel perspective for the study of HBV infection and relevant diseases.

Current Progress of Virus-mimicking Nanocarriers for Drug Delivery

Nanomedicines often involve the use of nanocarriers as a delivery system for drugs or genes for maximizing the therapeutic effect and/or minimizing the adverse effect. From drug administration to therapeutic activity, nanocarriers must evade the host's immune system, specifically and efficiently target and enter the cell, and release their payload into the cell cytoplasm by endosomal escape. These processes constitute the early infection stage of viruses. Viruses are a powerful natural nanomaterial for the efficient delivery of genetic information by sophisticated mechanisms. Over the past two decades, many virus-inspired nanocarriers have been generated to permit successful drug and gene delivery. In this review, we summarize the early infection machineries of viruses, of which the part has so far been utilized for delivery systems. Furthermore, we describe basics and applications of the bio-nanocapsule, which is a hepatitis B virus-mimicking nanoparticle harboring nearly all activities involved in the early infection machineries (i.e., stealth activity, targeting activity, cell entry activity, endosomal escaping activity).

Functionalized protein nanocages as a platform of targeted therapy and immunodetection

To improve the therapeutic/diagnostic potentials of drugs and/or imaging contrast agents, various targeted delivery systems are actively being developed. Especially protein nanocages, hollow and highly symmetrical nanometer-sized cage structures that are self-assembled from multiple protein subunits, are emerging as powerful targeted delivery tools. Their natural abundance, biocompatibility, low toxicity, well defined size and high symmetry are a few of the favorable characteristics which render protein nanocages as near ideal carriers for pharmaceuticals and/or imaging probes. This review aims to highlight current progress in the development and application of protein nanocages in targeted drug delivery approaches with an emphasis on the use of antibodies as targeting motifs to achieve high selectivity toward specific targets.

Applications of human hepatitis B virus preS domain in bio- and nanotechnology

Human hepatitis B virus (HBV) is a member of the family Hepadnaviridae, and causes acute and chronic infections of the liver. The hepatitis B surface antigen (HBsAg) contains the large (L), middle (M), and small (S) surface proteins. The L protein consists of the S protein, preS1, and preS2. In HBsAg, the preS domain (preS1 + preS2) plays a key role in the infection of hepatocytic cells by HBV and has several immunogenic epitopes. Based on these characteristics of preS, several preS-based diagnostic and therapeutic materials and systems have been developed. PreS1-specific monoclonal antibodies (e.g., MA18/7 and KR127) can be used to inhibit HBV infection. A myristoylated preS1 peptide (amino acids 2-48) also inhibits the attachment of HBV to HepaRG cells, primary human hepatocytes, and primary tupaia hepatocytes. Antibodies and antigens related to the components of HBsAg, preS (preS1 + preS2), or preS1 can be available as diagnostic markers of acute and chronic HBV infections. Hepatocyte-targeting delivery systems for therapeutic molecules (drugs, genes, or proteins) are very important for increasing the clinical efficacy of these molecules and in reducing their adverse effects on other organs. The selective delivery of diagnostic molecules to target hepatocytic cells can also improve the efficiency of diagnosis. In addition to the full-length HBV vector, preS (preS1 + preS2), preS1, and preS1-derived fragments can be useful in hepatocyte-specific targeting. In this review, we discuss the literature concerning the applications of the HBV preS domain in bio- and nanotechnology.