Alzheimer's

New research from Stockholm University and Karolinska Institutet shows that viruses interact with proteins in the biological fluids of their host which results in a layer of proteins on the viral surface. This coat of proteins makes the virus more infectious and facilitates the formation of plaques characteristic of neurodegenerative diseases such as Alzheimer’s disease.

Viruses can only reproduce inside living cells and exploit the cellular machinery of their host to their benefit. However, before entering a host cell, viruses are just nanometer-sized particles, very similar to artificial nano particles use in medical applications for diagnosis and therapy.

Lower respiratory tract infection

Scientists from Stockholm University and Karolinska Institutet; have find that viruses and nanoparticles share another important property; they both become cover by a layer of proteins when they encounter; so the biological fluids of their host before they find their target cell. This layer of proteins on the surface influence their biological activity significantly.

Kariem Ezzat and his colleagues study the protein corona of respiratory syncytial virus (RSV); so in different biological fluids. RSV is the most common cause of acute lower respiratory tract infections in young children worldwide; so leading up to 34 million cases and 196,000 fatalities each year. “The protein corona signature of RSV in the blood is very different from that in lung fluids.

It is also different between humans and other species such as rhesus macaque monkeys, which also can be infected with RSV”, Kariem Ezzat says. “The virus remains unchanged on the genetic level. It just acquires different identities by accumulating different protein; so coronae on its surface depending on its environment. This makes it possible for the virus to use extracellular host factors for its benefit; also they’ve show that many of these different coronae make RSV more infectious.

The researchers from Stockholm University and Karolinska Institutet; so they have also find that viruses such as RSV and herpes simplex virus type 1 (HSV-1) can bind a special class of proteins called amyloid proteins. Amyloid proteins aggregate into plaques that play a part in Alzheimer’s disease where they lead to neuronal cell death.

Transformation of soluble amyloid

The mechanism behind the connection between viruses and amyloid plaques; which has been hard to find till now, but Kariem Ezzat and his colleagues found that HSV-1 is able to accelerate; so the transformation of soluble amyloid proteins into thread-like structures that constitute the amyloid plaques. In animal models of Alzheimer’s disease, they saw that mice developed the disease within 48 hours of infection in the brain. In absence of an HSV-1 infection the process normally takes several months.

The novel mechanisms describe in our paper can have an impact; so not only on understanding new factors determining how infectious a virus is, but also on devising new ways to design vaccines. In addition, describing a physical mechanism that links viral and amyloid causes of disease adds weight; so to the increasing research interest in the role of microbes in neurodegenerative disorders such as Alzheimer’s disease; also opens up new avenues for treatments.”, Kariem Ezzat of Stockholm University and Karolinska Institutet says.