1. Dr. Sinan Bahjat M B Ch B, M Sc, F I B M S
Virology
Dr. Sinan Bahjat
M B Ch B, M Sc, F I B M S

2. Virology is the science that is concerned with the study of viruses.

3. In 1898, the two scientists Loeffler and Frosch found evidence that an infectious particle smaller than any bacteria can cause diseases in animals. This was the first attempt to describe the nature of viruses.

4. Viruses differ from other microorganisms by their dependence on the host cells that they infect in their reproduction.

5. Structure

6. Virus exists as a protein coat (i. e
Virus exists as a protein coat (i.e. capsid), sometimes with a membrane enclosing it. Either DNA or RNA is found inside the capsid, which codes for the virus elements.

7. The virus is metabolically inert outside the host.

9. Replication cycle of viruses

10. When it is attached to a host cell, a virus can insert its genetic material into that host cell, completely taking over the host's functions literally.

11. An infected cell produces more viral protein and genetic material instead of its usual products.

12. Some viruses can remain dormant inside host cells for long periods, causing no obvious change in these host cells (a stage known as the lysogenic phase).

13. But when a dormant virus is stimulated, it turns into the lytic phase, and new viruses will be formed, leading to cell death, then it turns to infect other cells.

14. Classification

15. Classification (Baltimore classification)
dsDNA viruses
ssDNA viruses
dsRNA viruses
Positive- sense ssRNA viruses
Negative- sense ssRNA viruses
RNA reverse transcribing viruses
DNA reverse transcribing viruses

18. Viruses in Dentistry

19. The main viruses that are related to dentistry are:
Human Papillomavirus
Herpesvirus
Mumps virus
Coxsackievirus

20. Human papillomavirus

21. Herpesvirus

22. Herpesvirus

23. Mumps virus

24. Coxsackievirus

26. Thank You