neuraminidase
Summary
Neuraminidase (sialidase) is an influenza surface glycoprotein that cleaves sialic acid residues from host cell glycoproteins, releasing newly assembled virions from the infected cell. It is the target of oseltamivir and zanamivir.
Detail
After replication, progeny influenza virions bud from the cell surface but remain tethered because their own hemagglutinin binds the sialic acid on the host membrane. Neuraminidase cuts these sialic acid residues, freeing the virions to infect new cells, and also thins respiratory mucus so the virus can reach the epithelium. Neuraminidase inhibitors — oseltamivir orally, zanamivir inhaled, peramivir intravenously — block this step, leaving virions clumped at the cell surface; they shorten illness by about a day and reduce complications, but only if started within roughly forty-eight hours of symptom onset. Zanamivir is inhaled and may provoke bronchospasm, so it is avoided in asthma and COPD. Baloxavir works by a different mechanism, inhibiting the cap-dependent endonuclease. Neuraminidase is also the N in strain designations such as H1N1 and H5N1, and it is a component of the inactivated influenza vaccine's protective response.
Sources
- Levinson Medical Microbiology and Immunology
- Katzung Basic and Clinical Pharmacology
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.