Enterovirus antibodies detected in acute flaccid myelitis patients

A new study analyzing samples from patients with and without acute flaccid myelitis (AFM) provides additional evidence for an association between the rare but often serious condition that causes muscle weakness and paralysis, and infection with non-polio enteroviruses.

An electron micrograph of a thin section of EV-D68, showing the numerous, spherical viral particles. Photo: Centers for Disease Control and Prevention

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. Both of these viruses typically cause mild respiratory illness from which most people recover fully. Despite the epidemiological link between enterovirus circulation and AFM cases, evidence of direct causality has not been found.

The researchers first looked for direct evidence of enterovirus infection in the cerebrospinal fluid (CSF) of 13 children and one adult diagnosed with AFM in 2018. They also examined five CSF samples taken from people with other central nervous system diseases.

The team used a new tool they developed called VirCapSeq-VERT, which can detect any viral genetic material that is at least 60% like that of any known vertebrate virus. They found enteroviral genetic material (EV-A71) in only the one adult AFM case and genetic material from another enterovirus (echovirus 25) in one of the non-AFM cases.

The investigators also sought indirect evidence of enterovirus infection by looking for antibodies to enteroviruses made by the immune system in response to an infection. The team developed a microchip assay, AFM-SeroChip-1, that detects the presence of antibodies generated in response to any human enterovirus (EV-A, EV-B, EV-C or EV-D) infection.

Using this assay, the team tested the same 14 CSF samples from the AFM patients. They also tested CSF samples taken from 11 adults with central nervous system conditions, such as multiple sclerosis, and from 10 children with Kawasaki disease, none of whom had AFM.

EV-specific antibodies were detected in the CSF of 79% (11 of 14) of the AFM cases. Of those, six samples were positive for EV-D68, strongly indicating that enterovirus had been in the central nervous system, even though it had not been detected by VirCapSeq-VERT. None of the CSF samples from children with Kawasaki disease had antibodies that reacted with any enterovirus.

This study provides further evidence that enterovirus infection may be a factor in AFM. In the absence of direct detection of a pathogen, antibody evidence of pathogen exposure within the central nervous system can be an important indicator of the underlying cause of disease. (National Institutes of Health)

YOU MAY ALSO LIKE

Behemoth Black Hole Found in an Unlikely Place

Astronomers have uncovered a near-record breaking supermassive black hole, weighing 17 billion suns, in an unlikely place: in the center of a galaxy in a sparsely populated area of the universe.

Fossil discovery in Tanzania reveals ancient bobcat-sized carnivore

Paleontologists working in Tanzania have identified a new species of hyaenodont, a type of extinct meat-eating mammal.

How the spleen keeps blood healthy

Researchers used computer modeling to show how the spleen maintains the quality of red blood cells in the bloodstream.

Graphene shield shows promise in blocking mosquito bites

Graphene could provide alternative to chemicals in insect repellant and protective clothing.

Pregnancy losses and large numbers of children linked with increased risk of cardiovascular disease

Women who experience pregnancy loss and do not go on to have children are at greater risk of cardiovascular disease, such as heart disease and stroke, compared with women who have only one or two children.

Scientists Find Virus Linked to Weight Gain

The prospect of a vaccine to stop gaining weight by eating fat is getting closer to reality after scientists found compelling evidence linking obesity to an infectious virus.