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Nanomaterials in Chemotherapy
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
P. K. Hashim, Anjaneyulu Dirisala
Virosomes can be a special category of HLs where the constituents are derived from virus components. Structurally, a virus consists of DNA or RNA gene segments surrounded by capsid proteins. Targeting ligands, such as glycoprotein, present in the virus surface recognize specific receptors on the cell membrane and internalize into the target cells. In some viruses, an additional lipid envelop is also present. Virosomes prepared from the influenza virus, hemagglutinating virus of Japan (HVJ virus), and hepatitis B virus are commonly investigated for drug delivery applications. By adding detergents to the virus-containing solution followed by centrifugation, genetic materials are first removed. Then, conventional phospholipids and cholesterol are added to the solution containing virus protein, where a coassembly process produces virosomes [125]. Depends on the viral protein and phospholipid composition, the size of virosomes can be varied, for instance, virosomes formed from HVJ have a mean diameter of 400–500 nm, while those from influenza are 150–200 nm. Because of ability to trigger membrane fusion, the HVJ-derived virosomes showed potential therapeutic application for the delivery of nucleic acids, proteins, and anti-cancer drugs. Importantly, HVJ-derived virosomes have intrinsic anti-tumor activities, activate multiple anti-tumor immunities, and induce cancer-selective apoptosis [126].
The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The attenuated Sabin vaccine and the inactivated Salk vaccine contain the capsid proteins of the three major serotypes of poliovirus. Immunity is conferred by the induction of virus-neutralizing antibodies to the capsid proteins. These neutralizing antibodies prevent infection of neurons. Compared to inactivated vaccines, attenuated live vaccines require smaller initial quantities of virus, and viral replication is required for induction of immunity. They must therefore be handled carefully during distribution and use to prevent inactivation and ensure infectivity. The major advantage of the inactivated vaccine, despite the need for larger initial amounts of virus, is that inactivation eliminates the possibility of reversion to the wild type virus.
Virus-Based Nanocarriers for Targeted Drug Delivery
Published in Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji, Viral and Antiviral Nanomaterials, 2022
Semra Akgönüllü, Monireh Bakhshpour, Yeşeren Saylan, Adil Denizli
The viral capsids, as outer protein walls, package the genome of the virus that is used in the delivery of drug molecules. The capsid proteins have governed by the packaging of the viral genome (RNA or DNA). Sequence and structural properties of the capsid protein and the viral RNA(s) play a magnificent role in genome packaging such as disassembly or self-assembly processes (Speir and Johnson 2012). The mechanism of virus packaging plays a significant role in drug delivery enforcement through reengineering capsids or blocking viral propagation. The capsid proteins can be reassembled into null viruses-like nanoparticles. So, this specific coat protein content can be able to utilise in drug delivery systems. These viruses-like nanoparticles have a rod-shaped and/or spherical shape.
Role of structural disorder in the multi-functionality of flavivirus proteins
Published in Expert Review of Proteomics, 2022
Shivani Krishna Kapuganti, Aparna Bhardwaj, Prateek Kumar, Taniya Bhardwaj, Namyashree Nayak, Vladimir N. Uversky, Rajanish Giri
The capsid protein interacts with lipids and helps in encapsidation of the viral genome. Its function may be similar to cellular histones in that it may have a role in charge neutralization and compaction of RNA [69]. The PrM associates with envelope protein and protects the fusion peptide. The cleavage of PrM give rise to mature membrane protein which is required to form an infectious virion [70]. The surface envelope glycoprotein mediates entry into host cells such as epidermal keratinocytes, fibroblasts, immature dendritic cells, stem cells derived human neural progenitors etc. It has three domains – EDI, EDII, and EDIII – which initiate fusion with a highly hydrophobic fusion loop and contains putative receptor-binding sites [71,72]. The fusion peptide region is present at the end of EDII. EDIII serves as a receptor attachment domain and also acts as an antigenic determinant site.
Differential expression of miRNAs in a human developing neuronal cell line chronically infected with Zika virus
Published in Libyan Journal of Medicine, 2021
Omar Bagasra, Narges Sadat Shamabadi, Pratima Pandey, Abdelrahman Desoky, Ewen McLean
Capsid protein is a ~ 12-kDa protein comprising the first ~105 residues of the ZIKV polyprotein. Capsid is the primary structural protein that interacts with the viral genome within virus particles and is essential for efficient packaging. Capsid dimers can bind a wide range of nucleic acid templates including the host RNAs, interfering in RNA splicing and RNA transcription. Capsid also enter the nucleolus and interacts with miRNAs and, therefore, may quell the molecular immune response against ZIKV [20,22]. Capsid protein expresses hydrophobic and hydrophilic regions that appear to play important roles in the pathogenesis of the virus. Capsid also causes significant dysregulation of host ribosomal biogenesis [20,22–25]. The hydrophobic regions of capsid proteins interact with the membrane of the endoplasmic reticulum (ER) whereas the hydrophilic region interacts with viral RNA. Binding of RNA to capsid starts particle formation by initiating aggregation of capsid. The aggregation of membrane-associated capsid into the nucleocapsid structure induces budding into the ER and the formation of immature virus particles. Capsid protein binds ssRNA, dsRNA and DNA in a sequence-independent manner via electrostatic interactions with the negatively charged phosphate backbone [20]. The packaging inside ER membrane compartments precludes capsid from packaging host RNAs.
Human papillomavirus and cervical cancer
Published in Journal of Obstetrics and Gynaecology, 2020
HPV is a member of the Papovaviridae family. It is a relatively small, non-enveloped virus of about 55 nm diameter. It has an icosahedral capsid with 72 capsomers and these contain at least two capsid proteins, L1 and L2. Each capsomer is a pentamer of the major capsid protein, L1 (Baker et al. 1991). Each virion capsid contains about 12 copies of the minor capsid protein, L2 (Sapp et al. 1995). The HPV genome consists of a single molecule of double-stranded, circular DNA (Favre 1975) with all open reading frame (ORF) protein-coding sequences confined to one strand. There are three functional regions in the genome (Figure 1, Stanley et al. 2007): the first is a ‘non-coding upstream regulatory region’ also referred to as the long control region (LCR), or the upper regulatory region (URR). This region contains the highest degree of variation in the viral genome and contains the p97 core promoter along with enhancer and silencer sequences that control ORFs transcription in the regulation of DNA replication (Apt et al. 1996). The second is called the ‘early region (E)’ and it consists of ORFs E1, E2, E4, E5, E6 and E7, which are involved in viral replication and tumorigenesis. The third is referred to as the ‘late region (L)’ and this encodes the L1 and L2 ORFs for the viral capsid. The E6, E7 and L1 ORFs of a new or unknown HPV type should be 90% or less homologous to the corresponding sequences of known HPV types (Torrisi et al. 2000).