Difference Between Alpha Beta Gamma and Delta Coronavirus

The key difference between alpha beta gamma and delta coronavirus is that alpha and beta coronavirus are mainly associated with infections in mammals while gamma and delta coronavirus primarily infects birds.

Coronaviruses are enveloped viruses containing positive-sense single-stranded RNA genome. They have characteristic club-like or crown-like spikes on their surfaces. Moreover, they possess a unique replication mechanism and an unusually large genome. They infect a wide variety of animals including mammals, birds, pigs, cows and humans. Therefore, they are zoonotic viruses. They cause mild to severe respiratory diseases. Transmission of coronavirus from person to person takes place through respiratory droplets and close contact with an infected person. There are four genera of coronaviruses. They are Alphacoronavirus, Betacoronavirus, Gammacorornavirus and Deltacoronavirus.

CONTENTS

1. Overview and Key Difference
2. What is Alpha Coronavirus
3. What is Beta Coronavirus
4. What is Gamma Coronavirus
5. What is Delta Coronavirus
6. Similarities Between Alpha Beta Gamma and Delta Coronavirus
7. Side by Side Comparison – Alpha Beta Gamma vs Delta Coronavirus in Tabular Form
8. Summary

What is Alpha Coronavirus?

Alphacoronavirus is a genus of coronaviruses. They are enveloped, spherical viruses which are about 120 nm in diameter. They have a genome composed of liner ssRNA(+) of 27 – 32 kb in size.

HCoV-NL63 and HCoV-229E are two human alphacoronaviruses that are responsible for the common cold in humans worldwide. Alphacoronavisus is derived from the bat gene pool.

What is Beta Coronavirus?

Betacoronavirus is another genus of coronaviruses that infect humans. SARS-CoV, MERS-CoV, and some HCoVs, including HCoV-OC43 and HCoV-HKU1, belong to this genus. SARS-CoV causes severe acute respiratory syndrome or SARS. SARS-CoV2 is the betacoronavirus that is responsible for the current global pandemic of COVID 19. MERS-CoV causes Middle East Respiratory Syndrome or MERS.

Many mammalian coronaviruses, including SARS-CoV and MERS-CoV are derived from bats. They are the natural reservoir of betacoronaviruses. They spread many mammalian coronaviruses among animals and humans.

What is Gamma Coronavirus?

Gammacoronavirus is another genus of coronaviruses. This group is also known as coronavirus group 3. They are mainly avian coronaviruses similar to deltacoronavirus. Gammacoronaviruses are spherical enveloped viruses having a diameter of 120 nm. Their RNA genome is associated with N proteins for the nucleocapsid.  Avian infectious bronchitis virus is a gammacoronavirus, and it has monopartite, linear ssRNA(+) genome of 27-32 kb in size.

What is Delta Coronavirus?

Deltacoronavirus is the fourth genus of coronaviruses. They derive from the avian gene pool and also from the pigs. Porcine Deltacoronavirus or PDCoV has a large viral genome of about 25.4 kb. A recombination is a frequent event seen in deltacoronaviruses. Hence, it is a risk of giving rise to new viruses capable of interspecies transmission and adaptation to new animal hosts.

What are the Similarities Between Alpha Beta Gamma and Delta Coronavirus?

• Alpha, beta, gamma and delta coronavirus are four genera of coronaviruses.
• They are zoonotic viruses.
• They all belong to order: Nidovirales, family: Coronaviridae and subfamily: Orthocoronavirinae.
• They are enveloped viruses.
• Their genomes are the largest among RNA viruses.
• Moreover, they have a single-stranded positive-sense RNA genome.
• They are non-segmented, 5’capped, and 3’ polyadenylated.
• Furthermore, they have at least the four canonical structural proteins; E (envelope protein), M (membrane protein), N (nucleocapsid protein), and S (spike protein).

What is the Difference Between Alpha Beta Gamma and Delta Coronavirus?

Alpha and Betacoronaviruses infect mammals while Gamma and Deltacoronaviruses primarily infect birds. So, this is the key difference between alpha beta gamma and delta coronavirus.

Below infographic summarizes the difference between alpha beta gamma and delta coronavirus.

Summary – Alpha Beta Gamma vs Delta Coronavirus

Coronaviruses are enveloped positive-sense single-stranded RNA viruses. There are four main genera as Alphacoronavirus, Betacoronavirus, Gammacoronavirus and Deltacoronavirus. Alphacoronavirus and betacoronavirus infect mammals, including humans while gammacoronavirus and deltacoronavirus infect birds. This is the key difference between alpha beta gamma and delta coronavirus. There are two human alphacoronaviruses (HCoV-229E and HCoV-NL63) while there are five human betacoronaviruses (HCoV-OC43, HCoV-HKU1, MERS-CoV, SARS-CoV and SARS-CoV2).

Reference:

1. “Alphacoronavirus ~ Viralzone Page”. Viralzone.Expasy.Org, 2020, Available here.
2. “Gammacoronavirus – An Overview | Sciencedirect Topics”. Sciencedirect.Com, 2020, Available here.
3. “Deltacoronavirus”. En.Wikipedia.Org, 2020, Available here.

Image Courtesy:

1. “Animal origins of human coronaviruses” – derivative work of an image by Firas A. Rabi, Mazhar S. Al Zoubi, Ghena A. Kasasbeh, Dunia M. Salameh, and Amjad D. Al-Nasser (CC BY 4.0) via Commons Wikimedia
2. “SARS-CoV-2 virion animation” By AustroHungarian1867 – Own work (CC BY-SA 4.0) via Commons Wikimedia