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The virus exits the host cell by nuclear egress, and nuclear pore export. [ 2 ] [ 3 ] A stem loop structure with a conserved nonanucleotide motif is located at the 5' intergenic region of circovirus genomes and is thought to initiate rolling-cycle replication.
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. [1] Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. [2] [3] Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.
Life-cycle of a typical virus (left to right); following infection of a cell by a single virus, hundreds of offspring are released. When a virus infects a cell, the virus forces it to make thousands more viruses. It does this by making the cell copy the virus's DNA or RNA, making viral proteins, which all assemble to form new virus particles. [37]
In most years, in the majority of samples tested, the influenza virus is not present (see figure above). In the United States during the 2008–9 influenza season through 18 April, out of 183,839 samples tested and reported to the CDC, only 25,925 (14.1%) were positive for influenza. The percent positive reached a maximum of about 25%. [5]
Pemeriksaan darah dan kultur virus (pemeriksaan untuk virus) dapat menyebabkan iritasi yang tidak perlu pada saluran napas. [4] Sedangkan kultur virus, yang diperoleh melalui aspirasi nasofaring (prosedur yang menggunakan selang untuk menghisap lendir dari hidung), dapat digunakan untuk memastikan penyebab sesungguhnya.
The virus wraps its delicate nucleic acid with a protein shell known as the capsid, from the Latin capsa, meaning "box," in order to shield it from this hostile environment. Similar to how numerous bricks come together to form a wall, the capsid is made up of one or more distinct protein types that repeatedly repeat to form the whole capsid.
The vaccinia virus is an effective tool for foreign protein expression, as it elicits a strong host immune-response. The vaccinia virus enters cells primarily by cell fusion, although currently the receptor responsible is unknown. [citation needed] Vaccinia contains three classes of genes: early, intermediate and late.
Once inside the plant, the virus spreads using plasmodesmata, a membrane channel found in plants connecting one plant cell to another. Caulimoviruses are para-retroviruses with a DNA genome; thus, part of their viral replication takes place in the nucleus, where the host replication machinery is utilized.