The virus and its replication
Measles is a class 5 virus (meaning it contains negative single stranded RNA as its genetic information).
Measles belongs to the family Paramyxoviridae
Measles is caused by Rubeola virus, and causes acute systemic infection.
Cases of measles in the UK have fluctuated over the years and have caused approximately 115,000 deaths a year. Infants are vaccinated against measles in the MMR vaccine. In 2016, WHO confirmed that the UK has eliminated measles. The MMR vaccine is highly effective and vaccine uptake has been considerably high.
Symptoms vary, such as rash, headache, fatigue, fever, persistent dry cough, running nose, and sore throat
Measles virus has various proteins to help with entering cells to infect:
Haemagglutinin – this protein attaches to CD46 using a dead neuraminidase domain.
Fusion protein – this protein interacts with the cell membrane to allow insertion of virus
Nucleoprotein -proteins that are structurally associated with nucleic acids, they tend to be positively charged and facilitate interaction with negatively charged nucleic acid chains. This associates to form the RNP complex.
Phosphoprotein – this also associates to form the RNP complex.
Large polymerase protein – Again, associates to form the RNP complex.
Matrix protein – associates with the RNP complex to move through the cell, it then associates with the plasma membrane (cell surface membrane) and the cytoplasmic tails of the haemagglutinin and fusion proteins.
As measles virus has a negative sense strand of ssRNA (single stranded RNA), this is used to create a positive copy, then is used to create a new negative copy. This continues to happen to create many copies of the ssRNA. The ssRNA is then mass translated by host (the infected person for example) ribosomes, producing necessary viral proteins. The viruses are then assembled, and the cell will lyse, restarting the cycle.
Is measles serious?
Measles will usually pass in over a week without symptoms getting worse, however, it can be rather unpleasant and uncomfortable. Having measles once means that the body will create an immune response to it, it will then remember the virus, so that it is unlikely you will get ill again from the virus. As if the virus enters the body again, the immune response has a memory of it, and knows how to respond to it quickly. However, for some, measles can lead to potentially life-threatening complications, usually in people with weaker immune systems. Infection could spread to the lungs (causing pneumonia) and to the brain (causing encephalitis.)
Measles can be spread through droplet infection, or touching the surface that droplets have spread onto. Quite similar to a cold really.
The best treatment is supportive treatment, give the patient fluids and antipyretics. There is no specific antiviral therapy available for measles.