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Prior to entry, a virus must attach to a host cell. Attachment is achieved when specific proteins on the viral capsid or viral envelope bind to specific proteins called receptor proteins on the cell membrane of the target cell. A virus must now enter the cell, which is covered by a phospholipid bilayer, a cell's natural barrier to the outside ...
To enter the cells, proteins on the surface of the virus interact with proteins of the cell. Attachment, or adsorption, occurs between the viral particle and the host cell membrane. A hole forms in the cell membrane, then the virus particle or its genetic contents are released into the host cell, where replication of the viral genome may commence.
It is the first step of viral replication. Some viruses attach to the cell membrane of the host cell and inject its DNA or RNA into the host to initiate infection. Attachment to a host cell is often achieved by a virus attachment protein that extends from the protein shell , of a virus. This protein is responsible for binding to a surface ...
Viruses have also developed a variety of immunomodulation mechanisms to subvert the host immune response. This tend to feature virus-encoded decoy receptors that target cytokines and chemokines produced as part of the host immune response, or homologues of host cytokines.
Influenza hemagglutinin (HA) or haemagglutinin [p] (British English) is a homotrimeric glycoprotein found on the surface of influenza viruses and is integral to its infectivity. Hemagglutinin is a class I fusion protein, [1] [2] having multifunctional activity as both an attachment factor and membrane fusion protein.
Once in the upper airway, the viruses may make their way into the lungs, where they invade the cells lining the airways, alveoli, or lung parenchyma. [44] Some viruses such as measles and herpes simplex may reach the lungs via the blood. [60] The invasion of the lungs may lead to varying degrees of cell death. [44]
Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the valves. [1] Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count.
Respiratory syncytial virus (RSV), [a] also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. [2] Its name is derived from the large cells known as syncytia that form when infected cells fuse. [2] [3]