Viruses: Virus structure and expression

 Some large viruses are present like filamentous forms of viruses, influenza and Ebola, they are basically too large to utilize caveolae, or other commonly used entry routes. In its place, these viruses trigger internalization by activating micropinocytosis which is a specimen of viruses reprogramming cells to assist virus replication. The other important structural feature is the surface of the virion. There are some types of viruses called enveloped viruses are not stable outside of the human body and are typically transmitted by transfer of body fluids. Where nonenveloped viruses are much more stable, and most of them can be transmitted by other mechanisms like faecal–oral route, this is also the way how polio and many other GI viruses are transmitted. In the case of Hepatitis, from contaminated shellfish for example, is caused by hepatitis A, a nonenveloped virus that is stable outside of the human body. In contrast, hepatitis B and C viruses have envelopes, and are transmitted by sexual contact or by blood.