Acellular infectious agents.pptx

celluar

1. Acellular infectious agents

2. Acellular infectious agents entities exist as smaller and less complex in structure but affect our lives. Viruses - are infectious agents made up of nucleic acids (DNA or RNA) that are enclosed within a protein coat called capsid. Viroids – are infectious RNA particles with sizes even smaller than viruses, viroids are not closed by a protein coat. Prions – are the simplest form of acellular infectious particles.

3. Viruses

4. A virus found outside aa cell is called virion , an inert particle that cannot grow, cannot move, cannot replicate on its own and cannot undergo biosynthetic or biochemical activity. A number of human diseases are caused by viruses including polio (polio virus), small pox (small pox virus), hepatitis (hepatitis virus), dengue (dengue virus), AIDS and many other viral diseases. Most of this diseases have no cure or would require a vaccine to prevent them from harming us.

5. The different identified viroids infect only plant tissues causing crop damages. Characterized viroids include those that cause spindle tuber disease in potatoes, viroids that cause the stunning growth of chrysanthemum plants. Viroids that cause cucumber pale fruit disease, and the viroids that cause cadang-cadang disease in coconut trees that almost wiped out of the Philippine coconut industry. It s said that prions do not exist inside our bodies although their function is not well understood.

6. Viroids

7. Prions are identified as the main cause of several brain diseases in animals including mad cow disease in cattle; scrapie disease in sheep and goats. All diseases associated with prions cause changes n brain tissues to results to its spongy appearance. Infected animals exhibit abnormal behavior that may later lead to death. Recent studies indicate that prions can be transmitted from one animal to another or through the consumption of prion-infected meat.

8. Prions