Virus RNA

 

Group 1: dsDNA viruses (e.g., Smallpox)

1. The virus enters the host cell and releases its double-stranded DNA (dsDNA).
2. The host’s RNA polymerase reads the dsDNA.
3. It makes mRNA from the DNA template.
4. The mRNA goes to the host’s ribosomes to make viral proteins.

• Enzyme used: RNA polymerase (host)

Group 2: +ssDNA viruses (e.g., Parvovirus)

1. The virus enters the host cell and releases single-stranded DNA (+ssDNA).
2. The host’s DNA polymerase copies +ssDNA into dsDNA.
3. Then, host RNA polymerase reads the dsDNA and makes mRNA.
4. mRNA is used by ribosomes to make viral proteins.

• Enzymes used:
  
• DNA polymerase (host) to make dsDNA
• RNA polymerase (host) to make mRNA
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Group 4: +ssRNA viruses (e.g., Coronaviruses)

1. The virus enters the host cell with +ssRNA, which acts like mRNA.
2. Ribosomes can start translating it right away to make viral proteins.
3. To replicate, the virus uses viral RNA-dependent RNA polymerase (RdRP) to make a -ssRNA copy.
4. Then it uses -ssRNA to make more +ssRNA.

• Enzyme used for replication: RdRP (viral)
• mRNA is already present as +ssRNA

Group 5: -ssRNA viruses (e.g., Measles)

1. The virus brings in -ssRNA (not readable by ribosomes).
2. The virus must bring its own enzyme: RNA-dependent RNA polymerase (RdRP).
3. RdRP makes +ssRNA (mRNA) from -ssRNA.
4. The mRNA is used by ribosomes to make proteins.

• Enzyme used: RdRP (viral)

Group 6: +ssRNA-RT viruses (e.g., HIV)

1. The virus brings +ssRNA and the enzyme reverse transcriptase.
2. Reverse transcriptase (RT) converts +ssRNA into dsDNA.
3. The dsDNA goes into the host’s nucleus and integrates into the host genome.
4. Host RNA polymerase transcribes the viral DNA into mRNA.
5. mRNA goes to ribosomes to make viral proteins.

• Enzymes used:
  
• Reverse transcriptase (viral)
• RNA polymerase (host)
•