What are the transmission routes of prions

Prions, also known as protein infection factors, toxins or infectious proteins, are a class of small, non-immune, hydrophobic proteins that can infect animals and replicate in host cells. Prions are a type of infectious pathogenic factor that can cause central nervous system lesions in mammals and humans. American biologist S. Prusiner believed that prions are protein infectious particles.

Prions are also called protein purifying factors, which are infectious proteins. This infectious protein can cause serious effects on the central nervous system of mammals and humans. It is a zoonotic disease with relatively high hazards. The source of the virus is mainly the bone feed of edible animals and heterologous infections. Once the disease occurs, the mortality rate is almost 100%.

1. Edible animal meat and bone meal feed

The transmission routes of prions include eating animal meat and bone meal feed, beef bone meal soup; and nosocomial infection, such as the use of pituitary growth hormone, gonadotropin, dura mater transplantation, corneal transplantation, blood transfusion, etc. The characteristic of prions is that they are resistant to digestion by proteases and conventional disinfection. Since they do not contain nucleic acids, they cannot be detected using conventional PCR technology. Prions are subject to mutation and cross-racial infection, and have a large number of potential sources of infection, mainly ruminants such as cattle and sheep. The unknown potential hosts may be very wide, and the potential danger of transmission is unclear, making it difficult to predict and infer. Prions can infect multiple organs, the main known one is the brain, but during the incubation period, various tissues and organs except the central nervous system can be infected, and there are multiple routes of infection. In addition to the digestive tract, the nervous system and blood can be infected, making prevention difficult. Once humans and animals are infected, all will die within 6 months to 1 year, with a 100% mortality rate.

2. There are two ways of transmission of human prion disease.

The first is hereditary, that is, familial prion infection in humans; the second is iatrogenic, such as corneal transplantation, implantation of EEG electrodes, careless use of contaminated surgical instruments, and injection of growth hormone taken from the human pituitary gland. As to whether the virus is contagious between humans and animals, there is no definitive conclusion yet, and this needs to be confirmed by further research by scientists.

3. It is highly infectious when in direct contact with infected tissue.

For example, people can get Gerstmann-Creutzfeldt-Jakob disease or variant CJD from injections of growth hormone derived directly from the human pituitary gland, or from instruments used in brain surgery (prions can survive the autoclaves that typically sterilize surgical instruments). It is also generally believed that eating infected animals can cause disease slowly through accumulation, particularly through cannibalism or similar behaviors that can cause prions to accumulate over generations, such as the case of kuru on a small Pacific island. While this risk has not been proven, it is a cautionary tale that modern farms do not accept feeding ruminants ruminant protein powders.