Difference Between Orthomyxovirus and Paramyxovirus

The key difference between orthomyxovirus and paramyxovirus is that orthomyxovirus has a segmented RNA genome while paramyxovirus RNA genome is not segmented.

Myxoviruses are influenza viruses. These viruses show affinity to mucins. There are two groups as orthomyxovirus and paramyxovirus. Orthomyxovisu and paramyxovirus are two groups of viruses that have negative-sense single-stranded RNA genomes. They are helical-shaped viruses which are enveloped. Orthomyxovirus has an RNA genome segmented into eight pieces, while paramyxovirus has a non-segmented genome.

CONTENTS

1. Overview and Key Difference
2. What is Orthomyxovirus 
3. What is Paramyxovirus
4. Similarities Between Orthomyxovirus and Paramyxovirus
5. Side by Side Comparison – Orthomyxovirus vs Paramyxovirus in Tabular Form
6. Summary

What is Orthomyxovirus?

Orthomyxoviru is a small virus with a negative sense single-stranded genome which consists of 8 RNA pieces. Therefore, the genome of orthomyxovirus is segmented. It is made from a helical nucleocapsid. Moreover, it is an enveloped virus having a lipoprotein outer envelope. Influenza A, B and C belong to orthomyxoviruses. Orthomyxoviral particles have a size ranging from 80 to 120 nm in diameter. These viruses also have endogenous RNA polymerase. They cause illnesses in the lower and upper respiratory tract. This virus is transmitted from one person to another person via aerosols of respiratory secretions.

What is Paramyxovirus?

Paramyxovirus is a large virus with a negative-sense single-stranded RNA genome. It contains RNA-directed RNA polymerase. Paramyxovirus is made up of helical nucleocapsid. The viral genome is not segmented in paramyxovirus.  The size of the paramyxovirus ranges from 150 nm to 300 nm. It is an enveloped virus with a viral attachment protein and a fusion protein. Paramyxovirus is replicated in the host cell cytoplasm.

Paramyxoviruses are responsible for acute respiratory diseases. They are transmitted by airborne droplets or direct contact. The paramyxoviruses are agents of diseases such as mumps, measles (rubeola), RSV (respiratory syncytial virus), Newcastle disease, and parainfluenza.

What are the Similarities Between Orthomyxovirus and Paramyxovirus?

• Orthomyxovirus and Paramyxovirus are RNA viruses that are enveloped.
• Their protein capsid is helical in shape.
• The multiplication of all paramyxoviruses is similar to that of orthomyxoviruses.
• They transmit via aerosols.

What is the Difference Between Orthomyxovirus and Paramyxovirus?

The key difference between orthomyxovirus and paramyxovirus is that genome of orthomyxovirus is segmented while the genome of paramyxovirus is not. Orthomyxovirus is a single stranded RNA virus with segmented genome. It has eight RNA segments. Meanwhile, the paramyxovirus is also a single stranded RNA virus but with a non-segmented linear RNA genome.

Moreover, the orthomyxoviruses are small, and their sizes range from 80 nm to 120 nm. But, the paramyxoviruses are large, and their sizes range from 150 nm to 300 nm. Besides, orthomyxovirus can cause influenza types A, B and C while paramyxovirus can cause mumps, measles, parainfluenza 1-4 infections and RSV diseases. Furthermore,concerning the site of synthesis of ribonucleoprotein, in orthomyxoviruses, it is nucleus while in paramyxoviruses, it is the cytoplasm.

The below infographic compares both viruses and tabulates side by side the differences between orthomyxovirus and paramyxovirus.

Summary – Orthomyxovirus vs Paramyxovirus

Orthomyxovirus and paramyxovirus are two single-stranded RNA viruses which cause respiratory tract infections. They are the enveloped viruses which are made from helical nucleocapsids. Orthomyxovirus genome is segmented and has 8 RNA pieces. Paramyxovirus genome is not segmented. Moreover, orthomyxovirus is small while paramyxovirus is large. Furthermore, orthomyxovirus is replicated in the nucleus while paramyxovirus is replicated in the cytoplasm. Thus, this summarizes the difference between orthomyxovirus and paramyxovirus.

Reference:

1. Enders, Gisela. “Paramyxoviruses.” Medical Microbiology. 4th Edition., U.S. National Library of Medicine, 1 Jan. 1996, Available here.
2. Couch, Robert B. “Orthomyxoviruses.” Medical Microbiology. 4th Edition., U.S. National Library of Medicine, 1 Jan. 1996, Available here.

Image Courtesy:

1. “Influenza nomenclature” By Burschik – Own work (CC BY-SA 3.0) via Commons Wikimedia

2. “Measles, virus, paramyxovirus, genus, morbillivirus” (CC0) via Pixino