New study examines body’s immune response to Lassa virus

A new report from the Infectious Diseases Society of America (IDSA) recently described for the first time a patient’s immune response at the cellular level in response to infection with the Lassa virus.

The patient involved with the study is a male American nurse who was working in Togo, West Africa when he became ill with the virus. After the man was diagnosed, he was evacuated to Emory University Hospital in Atlanta, Georgia for treatment. He was subsequently discharged from the hospital after a 25-day recovery period.

During his observation period, several semen samples were taken from the patient, which revealed detectable levels of Lassa RNA, including a sample up to 23 days after his discharge. Additionally, the man also developed inflammation of the epididymis. The researchers also tracked the man’s activity and function of virus-specific T-cells.

According to the study results, the patient’s immune response was “surprisingly robust” and correlated closely with several symptoms and signs that developed late in his illness, even after the virus could no longer be detected in his blood. The response suggests, the researchers said, that aspects of the patient’s own immune system might have caused some harm.

The discovery of the harmful immune response could lead to the development of new treatments for the virus that lessen certain harmful aspects in combination with medicines that fight the virus itself.

“First and foremost, we need to do this same type of research in more patients,”Anita McElroy, who worked on a similar Lassa virus study, said. “You’ve got to know what’s wrong in the immune response before you can attempt to fix it.”

In addition to the standard treatment for the virus, the patient was given a drug called favipiravir, an antiviral drug licensed to treat influenza in Japan, which has been studied as a possible drug to treat the Ebola virus. According to the study’s researchers, the patient experienced few serious side effects. However, clinical trials are needed to determine if the drug will be effective against Lassa virus.

Full details of the study were published in a recent issue of the Journal of Infectious Diseases.