Aug 13, 2019 - Health

NIAID working on enterovirus vaccine to fight acute flaccid myelitis

Photo of Enterovirus D-68, a suspect in causing AFM
Electron microscope photo of EV-D68, a suspect in causing AFM. Photo: Cynthia S. Goldsmith, Yiting Zhang/CDC

Recent research showing stronger links between an enterovirus and the polio-like illness called acute flaccid myelitis has led the National Institutes of Allergy and Infectious Diseases to start work on an EV-D68 vaccine, director Anthony Fauci tells Axios.

Why it matters: While rare, the devastating illness AFM suddenly strikes children, causing abrupt muscle weakness, paralysis or sometimes death. Researchers have been on the hunt for its cause — and while not definitive, the link with enterovirus D68 has grown stronger, including via a new study in the peer-reviewed journal mBio.

What's new: Using a new tool, scientists detected more traces of virus in this study, which was funded by NIAID.

"This is a hit-and-run virus. It comes in, does its bad thing, and leaves [while] its antibodies hang around."
— Anthony Fauci

The backdrop: Since the Centers for Disease Control and Prevention began tracking AFM in 2014, 574 patients have been confirmed, mostly children who often reported a respiratory or gastrointestinal illness in the weeks prior to the attack.

  • Spikes in AFM cases tended to happen during outbreaks of EV-D68 and EV-A71 — casting suspicion on these viruses as playing a role. However, most prior studies were unable to detect significant amounts of virus in the spinal fluid, despite some showing 40% of patients had evidence of enterovirus RNA in other samples.
  • A preliminary report published last month in the journal BioRxiv, which is not peer-reviewed, used different methods but also found higher levels of antibodies from enteroviruses in the spinal fluid of children who had AFM.
  • Viral presence in spinal fluid would indicate a stronger link to the illness, which affects the spinal cord's gray matter.
  • The illness appears to peak every other year (2014, 2016, 2018). For 2019, CDC has confirmed 13 cases in 8 states so far.

What they did: The mBio study examined the spinal fluid from AFM patients and compared them to non-AFM patients with other central nervous system diseases — looking for both genetic.

  • They first tested the samples of 14 AFM patients and 5 non-AFM patients through a highly sensitive viral genetic sequencing system.
  • They then looked for more indirect evidence of EV infections by developing a microchip assay to detect antibodies from any human enterovirus infection. They tested the same 14 AFM samples and compared them with 11 non-AFM patients.

What they found:

  • The initial genetic test found enterovirus RNA in only 1 adult AFM case and 1 non-AFM case.
  • But, the second test found roughly 79% had antibodies to enteroviruses — "significantly higher" than the controls, Fauci says.
  • While most people are exposed to EV-D68 and EV-D71 at some point resulting in antibodies, most do not have the antibodies in their spinal fluid, he adds.

What's next: The link between EV-D68 and AFM is strong enough that NIAID is in very early stages of developing a vaccine against it, Fauci tells Axios. "We might as well start now."

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Editor's note: This piece was updated to clarify the mBio study was 100% funded by NIAID and did not build on the preliminary findings posted in BioRxiv.

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