1. VIRUSES

2. VIRUSES considered non-living
Viruses cannot produce their own energy and cannot reproduce on its own
Viruses depend on a host cell to multiply

3. FEATURES OF THE VIRUS inner nucleic acid (DNA/RNA)
Capsid – outer protein coat
Envelope – extra layer (only for some viruses)

5. TYPES There are many virus types including: Retroviruses Adenoviruses
Rhabdoviruses etc…
Each has a different type of genetic material, protein coat and structure

7. THE HOST Host the cell that houses the virus
Virus can only infect a specific type of cell
Ex. Rabies virus – infects rodents, dogs, humans (it has a broad host range)
Ex. Human Cold Virus – only infects cells of the upper respiratory tract
Ex. HIV - only infects certain types of white blood cells (both have a narrow host range)

8. VIRUS REPLICATION PROCESS Lytic Cycle
Adsorption: Attachment and entrance
Virus rNA enters the host cell
Penetration
Engulfed in a vesicle
Uncoated
RNA is released In cytoplasm
synthesis
synthesis of viral proteins, nucleic acids and basic components
Assembly
Virus is formed from components
Release
Virus bud off – ready to infect another cell
Note: min. production of 100s of viruses

9. LYTIC CYCLE

10. LYSOGENIC CYCLE The virus is dormant/not active within the cell
Can pass through many generations without harm to the host
Can be activated by an environmental trigger  goes into lytic cycle
Example: HIV Virus and AIDS

11. LYSOGENIC CYCLE

12. Routes of transmission

13. INFLUENZA VIRUS Targets cells and cilia in upper respiratory tract
Symptoms: sore throat, congested lungs

14. Human Immunodeficiency Virus (HIV)
Targets immune system
causes AIDS (Acquired Immunodeficiency Syndrome)
Transmitted by bodily fluids: blood, semen, vaginal fluid, breast milk

15. Other Viral Diseases
Varicella zoster virus chickenpox (children) and shingles (adults)
Poliovirus - Polio
Variola major virus smallpox
SARS coronovirus Severe Acute Respiratory Syndrome (SARS)

16. VIRUSES AND CANCER Virus Cancer Type Human papilloma virus (HPV)
Some viruses can cause cancer by adding specific genes to an infected cell transforming it into a cancer cell
Virus
Cancer Type
Human papilloma virus (HPV)
Cervical
Hepatitis B/C
Liver
Epstein-Barr virus
Lymphoma