DNA Viruses
The genome of DNA viruses is made of deoxyribonucleic acid. They can be either dsDNA (double-stranded DNA) viruses or ssDNA (single-stranded DNA) viruses. In dsDNA viruses, the deoxyribonucleic acid is distributed into two strands. In ssDNA, it is just one strand of DNA. Both dsDNA and ssDNA have almost the same manner of transcription.
DNA viruses are present everywhere, especially in the marine ecosystem. Also, they infect both eukaryotes and prokaryotes. Examples – Poxviruses, Herpesviruses and Papillomaviruses.
RNA Viruses
The genome of RNA viruses is made of ribonucleic acid. They can also be classified into dsRNA and ssRNA. The dsRNA has many hosts, such as bacteria, animals, fungi and humans. Usually, RNA viruses have a higher mutation rate when compared to DNA viruses. Also, their genetic diversity makes it difficult to produce effective vaccines against them.
Baltimore Classification
It is a viral classification system that groups viruses into seven categories –
- Group â… – dsDNA viruses
- Group â…¡ – ssDNA viruses
- Group â…¢ – dsRNA viruses
- Group â…£ – positive-sense ssRNA viruses
- Group â…¤ – negative-sense ssRNA viruses
- Group â…¥ – ssRNA viruses with a life cycle intermediated with DNA
- Group â…¦ – dsDNA viruses with a life cycle intermediated with an RNA
Difference between DNA and RNA Viruses
DNA Viruses |
RNA Viruses |
|---|---|
| They are viruses that possess deoxyribonucleic acid (DNA) as their genetic material. | They are viruses that possess ribonucleic acid (RNA) as their genetic material. |
| The two types include – dsDNA and ssDNA viruses. | The two types include – dsRNA and ssRNA viruses. |
| They have a larger genome size. | They have a comparatively smaller genome size. |
| They show a low mutation rate. | They show a higher mutation rate. |
| Most DNA viruses are assembled in the nucleus. | Most RNA viruses are assembled in the cytoplasm. |
| They are included in the groups â… , â…¡, and â…¦ of the Baltimore classification. | They comprise groups â…¢, â…£, â…¤, and â…¥ of the Baltimore classification. |
| Examples – Poxviruses, Herpesviruses and Papillomaviruses. | Examples – Retroviruses, Reoviruses, Picornaviruses etc. |
Frequently Asked Questions
What are retroviruses?
It is a type of RNA virus that inserts its genome into the host cell’s DNA and eventually invades and changes the genome of the host cell. Here, the RNA viruses produce DNA from their RNA template. It is the reverse (retro) of the normal transcription process. Thus, the name retroviruses. Example – HIV.
What are the positive and negative senses of ssRNA?
The positive sense is directed from 5’ to 3’, and the negative sense is vice versa. The positive-sense ssRNA can be directly translated inside the host cell. Whereas the negative sense should be first transcribed into the positive sense, and then it undergoes translation.
Further Reading:
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