What are the 4 virus structure?

Viruses are classified into four groups based on shape: filamentous, isometric (or icosahedral), enveloped, and head and tail. Many viruses attach to their host cells to facilitate penetration of the cell membrane, allowing their replication inside the cell.

What disease is caused by picornavirus?

Infection with various picornaviruses may be asymptomatic or may cause clinical syndromes such as aseptic meningitis (the most common acute viral disease of the CNS), encephalitis, the common cold, febrile rash illnesses (hand-foot-and-mouth disease), conjunctivitis, herpangina, myositis and myocarditis, and hepatitis.

How do picornaviruses replicate?

Since picornaviruses spend all of their time in the cytoplasm, they must encode a polymerase (replicase) that is made from the sense strand of the infecting virus. The polymerase copies the sense strand to anti-sense which is then copied back to the sense strand that is packaged into the virus (figure 27).

What is the genome structure of Hepadnavirus?

Hepadnaviruses have small, enveloped, spherical virions (virus particles) that are about 40–48 nm (1 nm = 10−9 metre) in diameter. The capsid (the protein shell surrounding the viral nucleic acids) contains a circular double-stranded DNA molecule with a single-stranded DNA region and a DNA-dependent DNA polymerase.

Which is an example of a picornavirus virus?

Picornaviruses are small naked RNA-positive single-stranded viruses that include some of the most important pillars in the development of virology, comprising poliovirus, rhinovirus, and hepatitis A virus. Picornavirus infectious particles use the fecal–oral or respiratory routes as primary modes of transmission.

How big is the genome of a picornavirus?

Picornaviruses are classed under Baltimore’s viral classification system as group IV viruses as they contain a single stranded, positive sense RNA genome. Their genome ranges between 6.7 and 10.1 (kilobases) in length.

How did the picorna enterovirus get its name?

The name has a dual etymology. First, picorna- is an acronym for p oliovirus, i nsensitivity to ether, c oxsackievirus, o rphan virus, r hinovirus, and ribo n ucleic a cid. Secondly, pico-, meaning extremely small, combines with RNA to describe these very small RNA viruses. Enteroviruses infect the enteric tract, which is reflected in their name.

Where is the VPg located in a picornavirus?

Unlike mammalian mRNA, picornaviruses do not have a 5′ cap, but a virally encoded protein known as VPg. However, like mammalian mRNA, the genome does have a poly (A) tail at the 3′ end. An untranslated region (UTR) is found at both ends of the picornavirus genome.