Properties of Orthomyxoviruses and Paramyxoviruses

Last updated on May 13th, 2021

Influenza virus, the causative agent of seasonal flu (and pandemic flu) is the deadly contagious virus. It is the only virus of the medical importance of the family Orthomyxoviruses. Paramyxoviruses include the most important agents of viral respiratory tract infections notably Respiratory syncytial virus (RSV), Measles, Mumps, and Parainfluenza virus.

Some of the most important characteristics of these two families are:

Properties Orthomyxoviruses family Paramyxoviruses family
 Genera  Only one i.e. Orthomyxovirus (influenza virus)  3 genera; Paramyxovirus (parainfluenza viruses and mumps virus); Pneumovirus, (respiratory syncytial virus); and Morbillivirus (measles virus).
 Structure of the virion  Influenza-virus-structure  Paramyxovirus
 Capsid helical helical
Envelope present  present
 Virion size  smaller ( 80 to 120 nm in diameter.)  larger (150-300 nm in diameter).
 Surface spikes

Hemagglutinin (H) and Neuraminidase (N) in different spikes.

The viruses attach to permissive cells via the hemagglutinin subunit, which binds to cell membrane glycolipids or glycoproteins containing N-acetylneuraminic acid, the receptor for virus adsorption.

Hemagglutinin (H) and Neuraminidase (N) in the same spikes

Parainfluenza virus has both H and N activities, Measles lacks Neuraminidase activity and RSV lacks both H and N activities.

 Genome Single-stranded (SS), negative sense, segmented RNA
(influenza A virus has 8 segmented genomes)
 single-stranded (SS), negative sense, non-segmented RNA
 Antigenic variation  Antigenic shift (through genetic reassortment) can occur when a host cell is infected simultaneously with viruses of two different parent strains and antigenic drift.

Antigenic drift only.

Measles and Mumps has only one serotype so confers lifelong immunity.

Virion polymerase

#Remember;  negative-strand RNA virus has to do this.


Virally encoded RNA-dependent RNA polymerase transcribe and replicate the SS negative-sense RNA.


Virally encoded RNA-dependent RNA polymerase transcribe and replicate the SS negative-sense RNA.

Giant cell formation No


paramyxoviruses have the capacity to induce syncytia (multinucleated giant cells) formation.
Multinucleated giant cells originate from the fusion or division of mononuclear cells.

Diseases Febrile illness of the upper and lower respiratory tract (flu); pneumonia is the most common serious complication.

RSV and parainfluenza viruses cause mild or severe upper and lower respiratory tract infections,

Mumps cause characteristics swelling of parotid glands and other inflammations (pancreatitis, meningitis, encephalitis, orchitis, or oophoritis)


About Acharya Tankeshwar 474 Articles
Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. I am working as an Asst. Professor and Microbiologist at Department of Microbiology and Immunology, Patan Academy of Health Sciences, Nepal. If you want me to write about any posts that you found confusing/difficult, please mention in the comments below.

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