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Message de ioio98 posté le 27-11-2019 à 10:57:58 (S | E | F)
Est-ce que vous pouvez vérifier mon texte en anglais
Merci d'avance pour vos réponses !!
The measle is a highly contagious infection caused by a virus. The measle virus is a single stranded, negative polarity, enveloped, non-segmented RNA virus. Measle virus take part of groupe five. It belongs to family of paramyxovirdiae. Humans are natural hosts of the virus and the measle is an airborne disease which generate many complications like pneumonia, brain inflammation for example and the virus has an immunosuppressive effect. Sick people are vulnerable just as newborns because they are between 11 to 73% of their antibody which are eliminated. The most serious epidemics are in developing country. In those countries, the measle virus represent the principal cause of death to children between one and five years ago. We can ask: why vaccination is important?
I. Measle virus
The measle virus have 6 genes: F, H, L, M, N, P. The transcription complex effective of the measle virus composed of 3 protein: protein N, protein P, protein L and ARN. This complex is called ribonucleoparticle. The virus is constituted by a lipid envelope which come from host cell. On the inner face of the lipid envelope there is a matrix protein (M) and there are two surface glycoproteins: Hemagglutinin protein (H) and a fusion protein (F). Proteins H et F are responsible for the invasion of the virus in the host cells. There are 3 non-structural protein produced from the P gene : proteins V, C, R
Hemagglutinin protein (H) enable the attachment of the virus to the cell. Its possible because the protein H recognizing a particular receptor on the surface of host cell (CD46, CD150). Binding glycoprotein with a cellular receptor generates a modification to the form of the fusion protein. The fusion protein releases a hydrophobic fusion peptide which can be inserted in the cellular membrane
Fusion protein (F) is a viral protein which enable to fusion of bilayers lipid and cellular.
Matrix protein M constitute internal surface of the viral envelope. It creates a link between glycoproteins and the RNP (ribonucleoparticle) to assembling virions.
The wide protein L form with the protein P a RNA polymerase RNA dependent. The protein assured transcription, replication and maturation of messenger RNA.
Nucleoprotein N: it can interact with phosphoprotein P. It can be in the state of soluble monomer or in the state of nucleocapsid. Binds to genomic RNA
Phosphoprotein P: has 2 roles : It a chaperone role that keeps N in monomeric form and prevents the binding of RNA and a role as a cofactor of RNA polymerase (P interacts with the nucleocapsid and with RNA polymerase)
Protein V: The main function of this protein is to block the host's innate immune response and allow the virus to spread. It binds to a protein that activates the production of interferon and inhibits it. It blocks cell signalling pathways related to interferons.
Protein C: Like protein V, it inhibits the pathway of interferons in the liver, the virus that enters the host cell. It plays a role in the infectivity of the virus.
Entry of the organism + mode of infection
The measles virus enters the body through the respiratory tract. It replicates in immune cells residing in the respiratory mucous membranes. These cells then move to the lymph nodes and transmit the virus to the lymphocytes and monocytes present. The infection then spreads to the secondary lymphoid organs. Then we have the immune cells that are infected that circulate in the body and transmit the virus to the epithelial cells.
he measles virus enters by attaching itself via H proteins to receptors on the host cell. There are several receptors: Viruses can use SLAM and nectin-4 receptors and vaccine strains can also use CD46
- CD46: is found on all nucleated cells. This molecule plays a role in the regulation of complement. The hemagglutinin of the virus binds to the CD46 receptor and causes the internalization of the receptor. We have a fusion of the virus membranes and the target cell.
- CD150 or SLAM: a receptor found on the surface of NK cells and lymphocytes and dendritic cells. An SAP (SLAM associated protein) can bind to a cytoplasmic portion of the receptor, triggering a signaling cascade leading to the production of IL-4 and IL-13 by LTs and the production of IL-12 by macrophages. It is the receptor that allows the virus to replicate in the cells of the immune system. Little used in vivo
- Nectin -4: receptor expressed on the epithelial cells of the respiratory system and involved in the formation of adherens junctions. It is a receptor that allows the virus to replicate in the cells of the respiratory system.
Once the virus has attached to its receptor, it can enter the cell through a process of fusion or endocytosis.
The replication cycle
After the virus enters the cell, the RNP complex begins the transcription of parental (-) genomic RNA into (+) mRNA. We then have a synthesis of the viral proteins necessary for the replication of the viral genome by the cellular ribosomes. The glycoproteins in the envelope are synthesized from the ribosomes of the endoplasmic reticulum and transported through the Golgi apparatus to the cell membrane. The other proteins are produced in the cytosol. The viral genome is replicated as complementary (+) antigenomic RNA by viral RNA polymerase. The antigenome serves as a matrix for the synthesis of several copies of the virus genome. The new genomes assemble with the N, L, P proteins to form nucleocapsids that then move to the cell membrane to bind to the envelope proteins. The viral particle is released by budding.
Modifié par lucile83 le 27-11-2019 11:00
Réponse : Correction/measles de borntoulouse, postée le 27-11-2019 à 17:43:54 (S | E)
The disease is "the Measles" not "the measle" so the first line should be "The Measles is"
Some other changes...
The Measles virus takes part in group five.
belongs to the family
the Measles is an airborne
Modifié par lucile83 le 27-11-2019 17:46
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