High levels of enterovirus (EV) peptides were found in the cerebrospinal fluid (CSF) and serum samples of individuals with acute flaccid myelitis (AFM) that were not present in a variety of control individuals, according to the results of a small study of patients with and without AFM published online in mBio.
CDC
An electron micrograph of a thin section of EV-D68, showing the numerous, spherical viral particles.
In 2018, CSF samples from AFM patients were investigated by viral-capture high-throughput sequencing. These CSF and serum samples, as well as those from multiple controls, were tested for antibodies to human EVs using peptide microarrays, according to Nischay Mishra, PhD, of Columbia University, New York, and colleagues.
Although EV RNA was confirmed in CSF from only 1 adult AFM case and 1 non-AFM case, antibodies to EV peptides were present in 11 of 14 AFM patients (79%), which was a significantly higher rate than in control groups, including non-AFM patients (1 of 5, or 20%), children with Kawasaki disease (0 of 10), and adults with non-AFM CNS diseases (2 of 11, 18%), according to the authors.
In addition, 6 of 14 (43%) CSF samples and 8 of 11 (73%) serum samples from AFM patients were immunoreactive to an EV-D68–specific peptide, whereas samples from the three control groups were not immunoreactive in either CSF or sera. Previous studies have suggested that infection with EV-D68 and EV-A71 may contribute to AFM.
“There have been 570 confirmed cases since CDC began tracking AFM in August 2014. AFM outbreaks were reported to the CDC in 2014, 2016, and 2018. AFM affects the spinal cord and is characterized by the sudden onset of muscle weakness in one or more limbs. Spikes in AFM cases, primarily in children, have coincided in time and location with outbreaks of EV-D68 and a related enterovirus, EV-A71,” according to an NIH media advisory discussing the article.
In particular, as the study authors point out, a potential link to EV-D68 has also been based on the presence of viral RNA in some respiratory and stool specimens and the observation that EV-D68 infection can result in spinal cord infection.
“While other etiologies of AFM continue to be investigated, our study provides further evidence that EV infection may be a factor in AFM. In the absence of direct detection of a pathogen, antibody evidence of pathogen exposure within the CNS can be an important indicator of the underlying cause of disease,” Dr. Mishra and his colleagues added.
“These initial results may provide avenues to further explore how exposure to EV may contribute to AFM as well as the development of diagnostic tools and treatments,” the researchers concluded.
The study was funded by the National Institutes of Health. The authors reported that they had no competing financial interests.
SOURCE: Mishra N et al. mBio. 2019 Aug;10(4):e01903-19.