A virus known to cause respiratory infections in people — the human coronavirus (HCoV) — may also be the source of neurological diseases that strike patients, seemingly out of the blue, a new study reported.
Results obtained in the study, “Human Coronavirus OC43 Associated with Fatal Encephalitis,” support the idea that diseases of unknown origin — such as multiple sclerosis, Alzheimer’s, Parkinson’s, and, especially, encephalitis — may be induced by this virus. It was published in the New England Journal of Medicine.
Researchers investigated the case of an 11-year-old boy with severe immunodeficiency and symptoms of viral encephalitis. The virus, however, was not detected in this patient via conventional methods. The boy underwent a stem cell transplant, and died a month and a half after the treatment.
The team then used a modern laboratory technique that allows the detection of molecules produced by the virus, called deep sequencing, to analyze a brain biopsy sample. Through this technique, they found the presence of the human coronavirus (strand OC43) in the brain tissue, and confirmed it with other techniques as well.
“Among the methods used, deep sequencing of biopsy materials provides an important tool for the diagnosis of unexplained encephalitis, particularly in immunodeficient patients who have undergone stem cell transplantation,” said Pierre Talbot, one of the authors of the study, in a news release.
“The human betacoronaviruses, including HCoV-OC43, are predominantly associated with respiratory tract infections,” the team wrote. “The group includes viruses that cause the severe acute respiratory syndrome and the Middle East respiratory syndrome.”
Although this viral strand, HCoV-OC43, is typically “associated with mild upper respiratory tract infections,” the researchers continued, “it has been shown to have neuroinvasive properties.” In vivo studies in mice, specifically, have demonstrated that “HCoV-OC43 can infect neurons and cause encephalitis.”
Another study also detected this virus in the cerebrospinal fluid of a child with acute disseminated encephalomyelitis. In the case of multiple sclerosis, studies from the 1980s–90s have reported the presence of HCoV-OC43 in brain biopsies of MS patients.
The team concluded that the development of a standard method for identifying viruses or other pathogens can aid treatment decisions, namely in the choice of therapies for patients with neurological disorders.