Viruses lipids

As mentioned in Section 17.2.1, HA is a spike glycoprotein anchored to the virus lipid membrane [50], This glycoprotein functions as a receptor-binding protein and is responsible for the first step of viral infection when it binds to sialic acid residues of receptor glycoproteins on host cells [18]. When the virus is endocytosed into the cell, the low pH (5-6) changes the structure of HA, and this new fusion-active state triggers the fusion of the viral membrane and the endosome membrane, ultimately allowing entry of the viral nucleocapsid into the cytosol of the host cell [18]. 

The first steps in viral infection are binding of the virus to the cell surface, and, for viruses enclosed by a Upid membrane, the subsequent fusion of the virus and cell membranes to introduce the virus genetic material into the cell cytoplasm. Proteins embedded in the virus lipid bilayer envelope carry out cell surface receptor binding and membrane... 

Van Deemter equation. 54-55 Van der Waals interactions, 4 Video densitometers, 38 Viomycin, 462-463 Viruses, lipids extracted from, 690 Visual detection, 206-208 Visual estimation, 521 Vitamins ... 

The genes must enter the nuclease of a cell to be effective. Gene therapy vectors are not required, but greatly increase transfection efficiency. Genes can be delivered to a host through modified viruses, lipid or polymer complexes, cells modified ex vivo, or released from a scaffold. These methods are described in detail below (see Figure 18.1). 

Alphaviruses, such as Sindbis virus and Semliki Forest virus, are a group of mosquito-borne, enveloped RNA viruses that can cause encephalitis, fever, arthritis and rashes in mammals. These viruses have two protein shells—an outer glycoprotein layer and an inner core— which are separated by a lipid bilayer, a membrane. Studies by cryoelectron microscopy have shown that... 

Virus Any of a large group of submicroscopic agents infeeting plants, animals, and baeteria, and unable to reproduee outside the tissue of the host. A fully formed virus eonsists of nueleie aeid (DNA or RNA) surrounded by a protein, or protein and lipid eoat. 

Viruses are small infectious agents composed of a nucleic acid genome (DNA or RNA) encased by structural proteins and in some cases a lipid envelope. They are the causative agents of a number of human infectious diseases, the most important for public health today being acquired immunodeficiency syndrome (AIDS), hepatitis, influenza, measles, and vituses causing diarrhoea (e.g., rotavirus). In addition, certain viruses contribute to the development of cancer. Antiviral drugs inhibit viral replication by specifically targeting viral enzymes or functions and are used to treat specific virus-associated diseases. 

In some viruses, the capsid is surrounded by a lipid membrane (envelope), which is derived from the host cell membrane at the site of vims budding. The membrane contains viral envelope glycoproteins as well as host cell membrane proteins. 

HSV2 (herpes simplex virus 2), which causes significant morbidity and is an important cofactor for the transmission of HIV infection was recently targeted in a mouse model by local application of siRNA mixed with lipids. The results suggested that siRNA could work as active components of microbicides to prevent viral infection or transmission [2]. 

Viruses are infectious particles formed by nucleic acid, proteins, and in some cases lipids. As viruses (for example, retro- and adenoviruses) transfer viral genes into cells with high efficiency, modified forms are sometimes used as vectors for gene transfer. However, procedures using virus-based vectors are often significantly more complicated and time-consuming than other transfection methods. In addition, viral vectors are potentially hazardous, and biological safety issues need to be considered carefully. Therefore, techniques that combine... 

Flaviviruses Yeiiow fever virus Spherical particles 40 nm in diameter with an inner core surrounded by an adherent lipid envelope The virus is spread to humans by mosquito bites the liver is the main target necrosis of hepatocytes leads to jaundice and fever... 

Filoviruses Ebola virus Long filamentous rods composed of a lipid envelope surrounding a helical nucleocapsid lOOOnm long, 80nm in diameter The virus is widespread amongst populations of monkeys. It can be spread to humans by contact with body fluids from the primates. The resulting haemorragic fever has a 90% case fatality rate... 

Susceptibility of viruses to antimicrobial agents can depend on whether the viruses possess a lipid envelope. Non-lipid viruses are frequently more resistant to disinfectants and it is also likely that such viruses cannot be readily categorized with respect to their sensitivities to antimicrobial agents. These viruses are responsible for many nosocomial infections, e.g. rotaviruses, picornaviruses and adenoviruses (see Chapter 3), and it may be necessary to select an antiseptic or disinfectant to suit specific circumstances. Certain viruses, such as Ebola and Marburg which cause haemorrhagic fevers, are highly infectious and their safe destruction by disinfectants is of paramount importance. 

Jolly C, Sattentau QJ. Human immunodeficiency virus type 1 virological synapse formation in T cells requires lipid raft integrity. J Virol 2005 79(18) 12088-12094. 

The adamantane moiety is of medicinal chemical interest because of its inertness, compactness relative to lipid solubilizing character, and symmetry. Considerable interest, therefore, was engendered by the finding that amantadine (78) was active for the chemoprophylaxis of influenza A in man. There are not many useful chemotherapeutic agents available for the treatment of communicable viral infections, so this finding led to considerable molecular manipulation. The recent abrupt end of the National Influenza Immunization program of 1976 prompted a new look at the nonvaccine means for prophylaxis or treatment of respiratory tract infections due to influenza A, especially in that the well-known antigenic shift or drift of the virus obviates usefulness of the vaccine but not amantadine. 

---