What we are being treated for: vaccines against the 60-pointed death star
Why rotavirus infection victims die, why the genome of its pathogen looks completely insane for a molecular biologist, can you get vaccinated against rotavirus, if you are an adult, which vaccine is the best and safest and if Russia should be vaccinated nationwide – read the new issue of the rubric “What they treat us with.”
Intestinal but not flu
Rotavirus infection is often called “intestinal flu.” Although this name has nothing to do with the systematics of the viruses that cause it, it describes the symptoms well: fever, muscle and joint pain (like the flu) come along with symptoms from the gastrointestinal tract (nausea and diarrhea). Before the age of five, almost everyone has time to get sick at least once. Sometimes the infection is asymptomatic, leaving patients immunity as a gift. But not everyone is lucky: in 2013 alone, two million children were seriously ill with rotavirus, and 215,000 died. Approximately 23 children die from the disease every hour.
Mortality from rotaviruses in 2013 around the world: in the most developed countries it was less than ten people, and in the poor it reached more than 10 thousand. The leaders are India, Nigeria, Pakistan and the Democratic Republic of the Congo. There, half of the children under five born from rotavirus are born.
Strictly speaking, the virus alone does not kill a person. The cause of death is dehydration due to severe vomiting and diarrhea (37% of severe cases in children, however, are caused precisely by rotaviruses). The virus is transmitted by the fecal-oral route. “Is that necessary excrement to manage to get sick? Why then does anyone fail to avoid infection at least once in their life? ”The reader will be surprised.
The fact is that the virus feels great in soil and natural bodies of water. He will live in the environment for 9–19 days, and on human hands for several hours (unless, of course, this time can be called life, because scientists still argue about how viruses are “organisms”). Be that as it may, in one gram of feces of the patient there will be up to ten trillion viral particles, and about a hundred are needed for infection. There is a chance to catch the infection by airborne droplets, but how often it is transmitted through contaminated food is unknown. How is it treated and how is it prevented? To begin with, a little theory: you need to know the enemy by sight, and in the case of a virus, by capsid.
Rotavirus: inside and out
Rotaviruses are a type of virus that stores its genetic information in a very extravagant form: in 11 double-stranded RNA molecules, each of which scientists isolate as a gene. If in almost all organisms DNA (double-stranded) is a permanent form of recording genes, like a cookbook, and matrix RNA (single-stranded) is used to synthesize proteins, like a photocopy of one page (gene), then viruses can boast completely crazy ideas about this: here you can find both “single” DNA and “double” RNA, as in our hero. Viruses can afford not even that: they are not the only ones to excel in protein synthesis. They cunningly exploit other organisms, depriving them of the ability to make those proteins that ancestors bequeathed to DNA. Instead, the victims turn into factories of the exact same viral particles that will conquer their neighbors. In the case of rotaviruses, the cells of the small intestine are “attacked by clones”.
Rotavirus RNA is surrounded by a capsid shell consisting of 12 varieties of proteins: all rotavirus genes encode one protein, and only the ninth – two. True, their numbers are from 1 to 7, but this is because the protein from the RNA fragment No. 4 can be modified into a fifth, so for the fifth separate “recipe” in the virus genome is not written.
Rotavirus is not just crazy-written genetic information. The diagram shows six virion proteins (virion proteins, for short VP), of which the viral particle, i.e. the virion, is built. You will not find six nonstructural proteins (nonstructural proteins, or NSP) in the capsid, because they are produced only when the virus infects the cell
Non-structural proteins help to enslave internal cellular processes and adapt them to your needs, while capsid proteins serve mainly to attach to the victim cell and “convince” it to let itself pass under the membrane. To avoid retaliation from enslaved cells, even inside it, rotavirus RNA is protected by VP2 and VP6 proteins.
One of the VP proteins, VP1, is an RNA-dependent RNA polymerase, which helps to synthesize proteins from double-stranded RNA, “translating” it first into single-stranded RNA and without DNA at all. Although for some, like HIV, this madness goes even further: there a cell has to make DNA from a single-stranded RNA (and not vice versa, as usual) in order to produce RNA from it, and then only protein!