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The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
HBV is of global importance causing infection of over 250 million people. The virus is the primary agent transmitted by bloodborne routes such as needlestick injuries. Chronic HBV infection may be asymptomatic or result in hepatitis, which occurs in approximately five percent of individuals who acquire the infection, or it may cause hepatocellular carcinoma. Until the 1970s, the virus was difficult to study due to a lack of cell culture systems to propagate the virus and the lack of readily available animal models of the infection. The virus is transmitted by sexual contact and by exposure to the virus in contaminated blood or blood products including transmission from an infected mother to neonates at birth. HBV is a member of hepadnaviridae family of viruses. Other members include woodchuck hepatitis virus, ground squirrel hepatitis virus, and duck hepatitis virus. The other viruses provide some useful animal models of the infection in humans.
Applications of Antiviral Nanoparticles in Cancer Therapy
Published in Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji, Viral and Antiviral Nanomaterials, 2022
Anusha Konatala, Sai Brahma Penugonda, Fain Parackel, Sudhakar Pola
Liver cancer is the third leading cause of cancer deaths worldwide (American Cancer Society). The most common form of primary liver cancer in adults is hepatocellular carcinoma (HCC), or hepatoma. It accounts for approximately 75% of all liver cancers. Hepatitis B virus is the leading cause of HCC, whereas hepatitis C virus can also cause non-Hodgkin’s lymphoma. The risk of developing HCC increases with liver cirrhosis that can be caused by HBV/HCV infection and/or alcoholism. It must be noted that up to 25% of patients diagnosed have no history of cirrhosis or risk factors for HCC. Asia and Africa see a higher endemic prevalence of HBV and HCV, thereby increasing the incidence of HCC through an increased risk of chronic liver disease. HBV is an enveloped DNA virus of the hepadnaviridae family. The various treatment options available for HCC include liver resection/transplant surgery, radiofrequency/cryo-ablation, targeted chemotherapy (chemo-/radio-embolization), radiation, immunotherapy, etc., depending on the size and location, liver function, and overall health (Mayo Clinic).
Order Blubervirales: Surface Protein
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The order Blubervirales contains the sole family Hepadnaviridae, DNA viruses that are placed within the realm Riboviria because of homology between the hepadnavirus reverse transcriptase and the RNA-directed RNA polymerase of RNA viruses (Koonin et al. 2020). According to the current ICTV taxonomy report (Magnius et al. 2020) and current global review (Glebe et al. 2021), the Hepadnaviridae family includes 18 officially registered species divided into 5 genera depending on the viral host: Avihepadnavirus infecting birds, 3 species altogether including well-studied duck hepatitis B virus or DHBV; Herpetohepadnavirus infecting reptiles and frogs with one species; Metahepadnavirus infecting fresh and salt water teleosts, one species; Orthohepadnavirus infecting mammals and demonstrating a narrow host range for members of each 12 virus species; and Parahepadnavirus infecting freshwater teleosts, one species. The representative Orthohepadnavirus genus includes the hepadnaviral type representatives: hepatitis B virus (HBV), which infects humans and primates, as well as well-studied woodchuck (WHV) and ground squirrel (GSHV) hepatitis viruses. The hepadnaviruses are hepatotropic, and infections may be transient or persistent.
The roles of epidermal growth factor receptor in viral infections
Published in Growth Factors, 2022
Hepatitis B virus (HBV) belongs to the family Hepadnaviridae and its infection has caused a wide spectrum of liver diseases ranging from acute or chronic hepatitis, cirrhosis, and hepatocellular carcinoma. An infectious HBV virion, also known as Dane particles, consists of an outer lipid envelope and an icosahedral nucleocapsid that encloses partially double-stranded circular DNA genome and a DNA polymerase (Gerlich 2013). Studies by Iwamoto et al. (2019); Iwamoto et al. (2020) have revealed how HBV exploits EGFR endocytic machinery to enter the host cells. HBV binds to the host cell receptor, sodium taurocholate cotransporting polypeptide (NTCP) via the amino-terminal preS1 region of the viral large surface proteins (LHBs) and forms HBV/preS1–NTCP complex. EGFR mediates internalisation of HBV-NTCP complex via the direct interaction with NTCP. Internalised HBV is translocated to early and late endosome in concert with EGFR endocytic trafficking, which eventually leads to productive viral infection. Inhibition of EGFR using gefitinib and siRNA diminished virus internalisation (Figure 2(e)) (Iwamoto et al. 2019).
Envelope proteins as antiviral drug target
Published in Journal of Drug Targeting, 2020
Jyoti Verma, Naidu Subbarao, Maitreyi S. Rajala
Viruses belonging to the family Retroviridae, Paramyxoviridae, Herpesviridae and Hepadnaviridae can directly fuse their membrane with the host cell plasma membrane without being internalised by endocytosis [16]. The interaction between their envelope proteins with the receptor triggers the initiation of the fusion process. Instead of embedding into an endosome, these viruses create cell syncytia onto the host plasma membrane for their entry. The activation and conformational changes in their envelope protein to form fusion core occur at neutral pH [17]. This route is also known as the pH-independent entry of the virus, where the initial interaction of the envelope protein with its receptor leads to a conformational change, eventually exposing the fusion peptide. The exposure and relocation of the fusion peptide help the virus to fuse with the host cell membrane and release its genome into the cytoplasm of the host cell.
Adverse events, clinical considerations and management recommendations in rheumatoid arthritis patients treated with JAK inhibitors
Published in Expert Review of Clinical Immunology, 2018
Fabiola Atzeni, Rossella Talotta, Valeria Nucera, Francesca Marino, Elisabetta Gerratana, Donatella Sangari, Ignazio Francesco Masala, Piercarlo Sarzi-Puttini
HBV, which belongs to the Hepadnaviridae family, is characterized by partially double-stranded DNA, and HBV infection can lead to acute or chronic hepatitis, cirrhosis, or hepatocellular carcinoma. After infection, HBV DNA is incorporated in the host genome as a mini-chromosome. HBV reactivation has been observed during biological treatments for rheumatic diseases. Integration into hepatocyte genome occurs at more than 100 different sites, and some of the 148 insertion sites detected in patients with HBV-related hepatocellular carcinoma are major integration sites involved in the epigenetic control of gene translation, most of which cause the redundant expression of copies and lead to genomic instability.