Viral Diseases: Transmission, Symptoms and Prevention

Viruses are microscopic organisms that contain genetic material encased in a protein coat. They can only replicate inside living cells and are responsible for various diseases. Understanding different viral diseases and their transmission methods is crucial for prevention and treatment.

Understanding Viral Diseases: From Transmission to Prevention

• Virus Structure and Replication Mechanisms: A virus is a nucleic acid molecule (RNA or DNA) encapsulated in a protein coat or capsid. 
  • The virus is not a complete cell and can only replicate inside a living cell (bacteria, plants, fungi etc.). 
  • The capsid may have a protective lipid-containing envelope. The capsid and envelope facilitate attachment and penetration into host cells (e.g., via attachment to receptors like ACE 2) and often contain virulence factors. 
  • Inside the host cell, the nucleic acid molecule utilises cellular proteins and processes for virus replication. 
  • Based on the type of nucleic acids, viruses can be classified as:
• DNA Viruses: contain usually double‐stranded DNA (dsDNA) and rarely single‐stranded DNA (ssDNA). These viruses replicate using DNA‐dependent DNA polymerase. 

• • Example:  Adenovirus
• RNA Viruses: have typically ssRNA (single-stranded RNA) but may also contain dsRNA. 
• Retrovirus: Core contains several copies of reverse transcriptase bound to two identical single-stranded RNA molecules. 
  • Example: Human Immunodeficiency Virus (HIV)
• The key difference between RNA viruses and retroviruses is that RNA viruses are viruses that have single-stranded or double-stranded RNA as their genetic material, while retroviruses are viruses that have single-stranded RNA as their genetic material but use DNA intermediates in their life cycle.

Conclusion 

• Viruses cause a wide array of diseases ranging from the common cold to more severe conditions like AIDS and Ebola. 
• Vaccination, vector control, and proper hygiene practices play pivotal roles in preventing viral infections. 
• Continued research and public health efforts are essential to combating these viral threats effectively.