The scariest thing about prions is that they act not like predators, but like viruses. Predators are intelligent by nature and do not destroy all their victims. They simply multiply, infect and devour.
Everything else is completely indifferent to them,” explains the author of the best-selling book “World War Z,” Max Brooks, about his horror of zombies. But the same can be said about prions – the real killer zombie molecules.
Homo sapiens’ most unusual taste preferences was that of cannibalism. Fortunately, the consumption of people is found only in wild aboriginal tribes, cut off from civilization, and in works of fiction. The most striking example of the latter is the film “The Silence of the Lambs” thanks to the acting skills of Anthony Hopkins, who played Hannibal Lecter.
But despite such rare occurrences of cannibalism in the modern world, it can pose a threat to humanity, and not only from the point of view of the unfortunate people who fell under the cannibal’s knife. The problem is much more serious as cannibalism created the most dangerous disease in the world with 100% mortality, for which there is no cure.
Let’s turn our attention to Hannibal Lecter’s culinary preferences, especially fried brains. And of all the possible dishes throughout all the movies, Hannibal never ate a human brain himself, but only treated it to the people who shared the meal with him. And his refusal to consume the contents of the cranium makes sense, since the brain can be the source of a fatal disease – spongiform encephalopathy or prion disease.
Prion disease is a rare, degenerative, inevitably fatal brain disease that affects approximately one in a million people worldwide each year. It is characterized by rapid neurodegeneration, leading to memory loss, personality changes and motor coordination problems that worsen over time. It turns people into zombies.
Silence of the Lambs
The history of the study of the disease began in 1954, when Björn Sigurdson, a professor at the Reykjavik Institute of Experimental Pathology (Iceland), gave his famous lectures at the University of London on slow infections, a group of fatal transmissible spongiform encephalopathies commonly referred to as prion diseases.
Long before the official presentation of slow infections to the public, B. Sigurdson was invited by Icelandic farmers to determine the causes of mass diseases among sheep on various farms on the island. He encountered very diverse clinical manifestations of truly different diseases, among which there were signs of damage to the central nervous system in animals and disorders of the respiratory organs.
However, despite the differences in symptoms, B. Sigurdson discovered certain similarities between these diseases: an unusually long incubation period (years), a slowly progressive nature of the process, unusual damage to organs and tissues, and inevitable death. It is these four signs that formed the basis for the name of such diseases as slow infections.
“Kuru” – “laughing death”
Three years later, American pediatrician and virologist Daniel Carlton Gajduzek and medical worker in the Kainantu subdistrict in Papua New Guinea Vincent Zigas published the results of their research on the island of New Guinea, where the “kuru” disease with 100% mortality was widespread among the Papuan cannibals of the Fore tribe.
During his work with the Fore tribe, D. Gajduzek encountered a new disease that mainly affected women and children.
It all started with a headache and weakness, later convulsions were added, and, due to damage to the cerebellum, the gait became unsteady. Progressive paralysis deprived the person of the ability to move.
Newspapers gave it the name “laughing death” for its characteristic “smile” – the result of a spasm of the facial muscles. During the last days of his life, the patient’s already immobilized body was shaken by a characteristic “throwing up” trembling (hence the name of the disease, “kuru” = trembling). Despite treatment attempts, each case resulted in inevitable death.
It was also not possible to isolate the pathogen from the biomaterial of patients. When opening the skull of all the deceased, characteristic changes in the brain matter were discovered – it acquired a spongy structure. The main question remained unresolved: how was the disease transmitted from person to person?
The theory of heredity was put forward. However, after comparing the family trees of the victims, D. Gaiduzek realized that the sick were often not relatives.
Understanding the nature of the disease was facilitated by a more detailed study of the traditions of the tribe. The Aborigines ate their relatives for religious reasons: they believed that this ritual helped the deceased to remain with his fellow tribesmen as a spirit.
It turned out that during the cannibalism ritual, men got all the muscles, and women and children ate the remaining internal organs. The brain of the deceased was considered a particularly valuable product.
Having correlated all the facts, the researcher came to the conclusion that the disease was transmitted from person to person as a result of the aborigines eating the brain of a sick tribesman. In the course of scientific research, D. Gajduzek was able to transmit “kuru” to chimpanzees, and subsequently to lower apes, which proved the infectious nature of “kuru”. He hypothesized that the cause of the disease was a virus. By the way, he was faithful to this hypothesis until the end of his life. But everything turned out to be much more interesting.
Prions, the bringers of death
In the shadowy corners of molecular biology, where the lines between science and magic blur, lurk mysterious and eerie entities known as prions.
They are savages of the protein world, disregarding the rules by which other biological molecules live, and possessing sinister powers that can wreak havoc on the nervous systems of those they invade. At their core, prions are proteins that normally perform various functions in the cells of the body.
However, prions are proteins that have become misformed and become abnormally shaped, turning them from benign entities into sinister forces.
This irregular shape causes a domino effect, causing other, normal proteins to adopt the same irregular configuration. When prions accumulate in the brain, they lead to a number of neurodegenerative diseases.
All of these diseases are collectively known as transmissible spongiform encephalopathies (TSEs).
They are characterized by the gradual destruction of brain tissue, leading to severe and fatal neurological symptoms. The best known of these is Creutzfeldt-Jakob disease (CJD) in humans, which, like a thief in the night, quietly robs its victims of memory, personality and, ultimately, life.
The dark saga of mad cow disease
The incubation period for Creutzfeldt-Jakob disease is so long that some people who received the prion protein during the mad cow disease outbreak of the 1980s are only now beginning to show symptoms of the disease
The history of prions is steeped in mystery and fear. For decades, scientists have puzzled over the cause of some neurodegenerative diseases, in which the brain turns into a sponge-like mass riddled with holes.
The story of prions took a darker turn with the outbreak of bovine spongiform encephalopathy (BSE), better known as mad cow disease. At the end of the 20th century, the disease devastated Britain’s cattle population, leading to a public health crisis.
The outbreak was linked to the common practice at the time of feeding cattle meat and bone meal, which included the remains of other animals, to increase protein intake. Fear increased when it was discovered that BSE can jump from one species to another, causing a form of Creutzfeldt-Jakob disease in humans.
The discovery that these diseases are not caused by viruses or bacteria, but by the proteins themselves, shocked the scientific community. This was a paradigm shift that challenged the very foundations of infectious disease theory.
The mystery of prion transmission
Prions have the chilling ability to transmit their abnormal state not by replication, like viruses or bacteria, but through a kind of molecular persuasion. They convert normal proteins into their incorrect form, spreading disease within the body and, under certain conditions, between organisms.
The most common form of prion transmission is sporadic, that is, occurring without any reason. The disease usually affects people over the age of 50 and occurs with a probability of 1-2 cases per million inhabitants.
This spontaneous phenomenon is the underlying cause of most cases of Creutzfeldt-Jakob disease (CJD). It is believed to be related to the natural aging process, but this has not been proven.
Some cases of prion disease are familial, meaning they are caused by inherited mutations in the PRNP protein gene. These genetic mutations lead to the production of prion proteins, which are more prone to forming incorrectly.
Familial forms of prion disease are inherited in an autosomal dominant manner, meaning that only one copy of the mutated gene is required to inherit the disease.
Prion diseases can be acquired through contact with infected tissue. This form of transmission can occur in several ways: Some medical procedures can transmit prions if contaminated instruments are used. These include neurosurgical instruments, corneal transplants, dural transplants, and treatment with growth hormone derived from the human pituitary gland.
Variant Creutzfeldt-Jakob disease (vCJD) is associated with consumption of beef products contaminated with the prions that cause mad cow disease. In rare cases, prion diseases have been transmitted through blood transfusions from donors who were unknowingly infected with the vertebrogenic disease virus.
In France, many cases of Creutzfeldt-Jakob disease were caused in children due to medical errors, at least 200 cases were recorded.
Doctors administered drugs from the pituitary glands of animals suffering from bovine spongiform encephalopathy to stunted children. Subsequently, the medical workers were completely acquitted by the court.
It is important to note that prion diseases are not transmitted through casual contact, air, water, or touching an infected person or animal.
There is no escape
Prion diseases often show symptoms only after significant and irreversible damage has occurred to the brain. The blood-brain barrier, which protects the brain from pathogens, also makes it difficult for potential treatments to reach affected areas.
Developing drugs that can overcome this barrier and effectively target misfolded proteins is a major challenge in prion research.
Currently, there is no method that can stop or reverse the process of abnormal changes in protein structure and subsequent brain damage.
Let’s return to Creutzfeldt-Jakob disease. It accounts for about 85% of all human prion encephalopathies and affects people of all nationalities and races, men and women, adults and children. Irreversibility sets in. Subtle changes in behavior and mood appear, painting the personality with unfamiliar brushstrokes. Coordination is impaired.
The mind that was once a reliable narrator of one’s life story becomes increasingly fragmented. Personality changes become increasingly profound, sometimes manifesting in the form of anxiety or depression, sometimes in the form of uncharacteristic aggression.
In the final stages, Creutzfeldt-Jakob disease leads to a state of deep detachment. The once energetic man, full of bright stories and dreams, is now silent.
The duration of the disease is less than two years. Today it is incurable, death occurs in 100% of cases. The disease can occur at any age.
Diagnosis of Creutzfeldt-Jakob disease can be difficult and usually involves ruling out other causes of dementia. Specific diagnostic tests include electroencephalography (EEG), MRI of the brain, and cerebrospinal fluid (CSF) testing for disease markers.
