A brief talk on the cowpox

Cowpox is an infectious disease occurring in cattle. It is an acute infection caused by smallpox virus. Its symptoms are usually local ulcers in the breast of cows. The virus can be transmitted to humans through contact, mostly in milkers, slaughterhouse workers, patients with skin papules, these papules slowly develop into blisters, pustules, but also some other symptoms. Historically, most cases of the disease occurred in Europe, especially in the United Kingdom. The virus can be found in cattle, cats and voles. Human cases are rare and the incubation period is 9 to 10 days, but for patients with immune system deficiencies, cowpox virus infection is lethal enough. According to WHO's current report, the disease is now disappearing globally.

Cowpox virus is a virus that can cause mild varicella in cattle. If people are infected with the virus, they will only produce slight discomfort and resistance to cowpox virus. Since cowpox virus has the same antigenic properties as smallpox virus causing human smallpox disease, vaccination with vaccination can also acquire immunity against smallpox virus. After the 18th century, vaccination against highly infectious smallpox was the first successful case of vaccination.

The vaccinia virus, the viral capsid is composed of one to several proteins, and the subunits constituting the viral capsid are called shell particles. The formation of a virus does not require the participation of an enzyme, and as long as the conditions are met, the nucleic acid and the carrier protein can self-assemble into a virus. Once the vaccinia virus infects cells, it uses a unique mechanism to build a single-layer membrane -- a hypothesis that was introduced more than 30 years ago. However, in 1993, Krijnse-Locker's team found that vaccinia virus is firmly involved in the secretory pathway of the host vaccine cell lines and is ultimately coated by a bilayer membrane from the endoplasmic reticulum of the host cell. The size of the virus is generally between 10 and 30 nm. The structure is simple, consisting of a nucleic acid (DNA or RNA) core and a protein capsid, called a nucleocapsid, which protects the viral nucleic acid from enzymatic digestion. Various viruses contain different amounts of genetic information, and only a small number of three genes, and more than 300 different genes.

The viral capsid is composed of one to several proteins, such as the iodn and the subunits that make up the viral capsid are called shell particles. The formation of a virus does not require the participation of an enzyme, and as long as the conditions are met, the nucleic acid and the protein can self-assemble into a virus. Its assembly form has three types: icosahedral symmetry, spiral symmetry and composite symmetry. The icosahedral symmetrical capsid protein forms an icosahedron in which the nucleic acid is in the cpg a  encapsulated; the helically symmetric capsid protein and the nucleic acid are arranged in a spiral, and the nucleic acid is interlaced therein; the complex symmetry has or without two symmetry Sexual form of the virus.

A mature and infectious virus particle is called a "virion." There are five forms observed by electron microscopy; 1 spherical: most human and animal viruses are spherical, such as poliovirus, herpes virus and adenovirus; 2 filament: more common in plant viruses, such as tobacco mosaic virus, human influenza The virus is sometimes silky; 3 bullet shape: shaped like a bullet, such as rabies virus, herpetic stomatitis virus, etc., most of which are plant viruses. 4 brick shape: such as smallpox virus, vaccinia virus, etc.; 5 Tadpole-shape: consists of an oval head and a slender tail, such as phage. 1 is icosahedral symmetry; 2 and 3 are spiral symmetry; 4 and 5 are composite symmetry.

The results showed that the recombinant expression of vaccinia virus topoisomerase I can efficiently change the topology of supercoiled plasmids. The high expression of vaccinia virus topoisomerase I lays a foundation for the regulation of the cleavage and ligation activity of this enzyme and the in-depth study of its catalytic properties and its use in ligation reactions.