Home | | Botany | | Botany | Classification of virus

Chapter: 11th 12th standard bio zoology Human Body higher secondary school

| Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail |

Classification of virus

According to the type of the host they infect, viruses are classified mainly into the following four types. 1. Plant viruses including algal viruses-RNA/DNA 2.Animal viruses including human viruses-DNA/RNA 3.Fungal viruses(Mycoviruses)-ds RNA 4.Bacterial viruses (Bacteriophages) including cyanophages-DNA 1.Plant viruses

Classification of virus

 

Although viruses are not classified as members of the five kingdoms, they are diverse enough to require their own classification scheme to aid in their study and identification.

 

According to the type of the host they infect, viruses are classified mainly into the following four types.

 

1. Plant viruses including algal viruses-RNA/DNA 

2.Animal viruses including human viruses-DNA/RNA 

3.Fungal viruses(Mycoviruses)-ds RNA

4.Bacterial viruses (Bacteriophages) including cyanophages-DNA 


1. Plant viruses

 

They infect plants and cause diseases. Some common plant viral diseases are:

 

           Mosaic diseases of tobacco (TMV), cucumber (CMV), cauliflower.

 

           Bunchy top of banana

 

           Leaf-roll of potato

 

           Spotted wilt of tomato

 

Generally, plant viruses have RNA with the exception of some viruses such as cauliflower mosaic virus which has DNA.

 

2. Animal viruses

 

They infect animals and cause diseases. The nucleic acid is either DNA or RNA. some of the diseases caused by viruses in human beings are: common cold, measles, small pox ( now extinct) chicken pox, Jaundice, herpes, hapatitis A B,C,D,E,G, influenza, polio, mumps, rabies, AIDS and SARS. Viruses also cause diseases in cattle. eg. Foot and mouth disease. (FMD) in cattle, encephalomyelitis of horse, distemper of dog, rabbies etc.

 

3. Viruses that cause diseases in fungi are called mycophages and viruses that attack blue green algae/cyanobacteria and cause diseases are called cyanophages.


4. Bacteriophages

 

Virus that infects bacteria is called bacteriophage or simply phage. It is tadpole like and the nucleic acid is DNA eg. T2, T4, T6bacteriophages.

 

 

General characteristics

 

Viruses are ultramicroscopic and can cause diseases in plants and animals. They are very simple in their structure. They are composed of nucleic acid surrounded by a protein coat. Nucleic acid can be either RNA or DNA, but never both. They have no cellular organization and have no machinery for any metabolic activity. They are obligate intracellular parasites and they multiply within their host cells. Once outside the host cell they are completely inactive.

Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail


Copyright © 2018-2021 BrainKart.com; All Rights Reserved. (BS) Developed by Therithal info, Chennai.