Difference Between Bacteriophage and TMV

The key difference between bacteriophage and TMV is that bacteriophage is a virus which infects a specific bacterium while TMV is a virus which infects tobacco and a wide range of plants.

Viruses are tiny infectious particles that replicate only inside a living organism. They are obligate intracellular parasites that are capable of infecting almost all living organisms, including animals, plants, fungi, protozoa and bacteria. They are composed of a protein capsid and a DNA or RNA genome. The genome of the virus can be either DNA or RNA, single-stranded or double-stranded, circular or linear. A bacteriophage is a virus which attacks bacteria and replicates using bacterial replication machinery. Bacteriophages are the most abundant viruses in the biosphere, and they can have either DNA or RNA genomes. TMV or Tobacco Mosaic Virus is a plant virus. It infects tobacco and many other plants such as crops, ornamentals and weeds.

CONTENTS

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

What is a Bacteriophage?

A bacteriophage (phage) is a virus which infects and propagates inside a specific bacterium. They are also known as bacteria eaters since they act as bactericidal agents. Bacteriophages were discovered by Frederick W. Twort in 1915, and they were named as bacteriophages by Felix d’Herelle in 1917. They are the most abundant agents on earth. They are composed of a genome and a protein capsid. Bacteriophage genome can be either DNA or RNA, but, majority of bacteriophages are double-stranded DNA viruses.

Bacteriophages are specific to one bacterium or a specific group of bacteria. They are named with the bacterial strain or the bacterial species they infect. For example, bacteriophages which infect E coli are called coliphages. Bacteriophages show different shapes. The most common shape is the head and tail shape.

Bacteriophages should infect the host cell in order to reproduce. They are tightly attached to the bacterial cell wall using their surface receptors and inject their genetic material into the host cell. Bacteriophages can undergo two types of infection modes as lytic and lysogenic cycle. It depends on the type of phage. In the lytic cycle, bacteriophages infect bacteria and rapidly kill the host bacterial cell by lysis. In the lysogenic cycle, viral genetic material integrates with bacterial genome or plasmids and exists within the host cell for several generations without killing the host bacterium.

Phages have various applications in molecular biology. They are used to treat pathogenic bacterial strains which are resistant to antibiotics. Moreover, they can be used to identify specific bacteria in disease diagnosis.

What is TMV?

Tobacco Mosaic Virus (TMV) is a plant virus that infects the host plant Tobacco. Therefore, TMV is a tobacco pathogen. In addition to tobacco, TMV can also infect a very wide range of plants including numerous crops, ornamentals and weeds. TMV is one of the most studied plant viruses. In fact, it was the first virus to be so identified. Structurally, it is a positive-sense single-stranded RNA virus. It is a helical virus comprised of 2130 subunits of a single structural protein consisting of 157 amino acids in the protein capsid.

TMV is spread mechanically by abrasion with infected sap. The main symptoms of TMV infection are “mosaic”-like mottling and discolouration on the leaves. TMV is very closely related to tomato mosaic virus (ToMV). TMV enters plant cells through wounded tissues. Successful TMV infection requires initial establishment and accumulation in invaded cells, intercellular movement, and systemic transport. TMV multiplies only inside the living cells. But it can survive in a dormant state in dead tissues for years, retaining its ability to infect growing plants.

There are no chemicals to treat TMV. Some practices such as planting virus-free plants, removing weeds, removing crop debris, discarding infected plants, disinfecting tools and propagating plant from seeds, etc, can avoid TMV infection.

What are the Similarities Between Bacteriophage and TMV?

• Bacteriophage and TMV are viruses.
• They are obligate intracellular parasites.
• Both are infectious particles which cause diseases.
• They are composed of a protein capsid and a nucleic acid genome.
• They multiply only inside the living cells.
• Both bacteriophage and TMV are species-specific.

What is the Difference Between Bacteriophage and TMV?

Bacteriophage is a bacteria infecting virus while TMV is a plant virus which infects tobacco plant mainly. So, this is the key difference between bacteriophage and TMV. Moreover, most bacteriophages have a head-tail structure while TMV is a rod-shaped virus. Thus, this is another difference between bacteriophage and TMV.

The below infographic summarizes the difference between bacteriophage and TMV in tabular form.

Summary – Bacteriophage vs TMV

Bacteriophage is a virus that infects and replicates only inside a bacterium. TMV is a virus that infects and replicate inside tobacco plant cells and other Solanaceae plants. This is the key difference between bacteriophage and TMV. Majority of bacteriophages have head, legs and tail shape while TMV is a rod-like virus. Bacteriophages can have DNA or RNA genomes while TMV has a single-stranded RNA genome. Thus, this is the summary of the difference between bacteriophage and TMV.

Reference:

1. Moorman, Gary W. “Tobacco Mosaic Virus (TMV).” Penn State Extension, 27 Jan. 2021, Available here.
2. Kasman, Laura M. “Bacteriophages.” StatPearls [Internet]., U.S. National Library of Medicine, 1 Oct. 2020, Available here.

Image Courtesy:

1. “Structure of a Myoviridae bacteriophage 2” By Chelsea Bonnain, Mya Breitbart and Kristen N. Buck – extracted from this Commons file (CC BY-SA 4.0) via Commons Wikimedia

2. “TMV structure full” By Thomas Splettstoesser (www.scistyle.com) – Own work (CC BY-SA 3.0) via Commons Wikimedia