Medical scientists have been investigating a virus called enterovirus D68, which causes a very severe respiratory infection in children. This virus may be associated with a polio-like paralysis that has occurred in the United States and elsewhere.
But researchers have now determined the structure of the virus, along with the structure of enterovirus D68 when it is bound to an antiviral compound called pleconaril. These structures may help identify a class of chemical compounds that may be effective at fighting enterovirus D68 infections.
Enterovirus D68 has a protective shell called a capsid. There is a molecule within the capsid that is called the pocket factor. When the virus binds to a human cell, this pocket factor is squeezed out, an action that destabilizes the virus and causes it to release its genetic material into the cell, infecting the cell. After the human cell becomes infected, it starts to replicate the virus.
Pleconaril binds into the pocket, which inhibits the virus's ability to infect a human cell.
"The compound and the normal pocket factor compete with each other for binding into the pocket," said Michael G. Rossmann, Hanley Distinguished Professor of Biological Sciences at Purdue University and an author of a paper on this research. The paper was published in the journal Science.
However, this research was conducted with one version of enterovirus D68 that was discovered in 1962, when the virus was first identified. Current strains of enterovirus D68 have minor differences. Pleconaril has not been found to be active against strains of the virus that have been tested so far. However, now that the structure of the virus is known, anti-viral research is better able to find an active compound.
There has been an upsurge of identified cases of enterovirus D68, with infections worldwide. An outbreak of respiratory disease occurred in thousands of children in the United States in 2014. Around 1150 cases were confirmed to be due to enterovirus D68. The virus has also been associated with neurological infections and to a condition called acute flaccid myelitis, which causes muscle weakness and paralysis. There is no antiviral treatment or vaccine for enterovirus D68 as yet.