medicines and drugs antivirals

Diseases caused by viruses influenza SARS measles smallpox AIDS avain flu Polio meningitis (can be both bacterial and viral) pneumonia (also caused by both bacteria and viruses)

virus

antivirals treat viral infections usually virus specific – not broad not that many antivirals available do not destroy but inhibit development of target virus Does not destroy host cell pills, liquids, inhalers, intravenous

bacteria virus bacteria vs virus bacteria are self-reproducing, without a host i.e. by cell division viruses are not self-reproducing as they need a host cell (such as bacterial cell) to multiply; as a result the host cell dies bacteria are able to grow, feed and excrete viruses lack any metabolic functions so they do not grow, feed or excrete bacteria contain organelles such as cytoplasm, cell wall and nucleus which all perform specific functions viruses consist only of genetic material and protective coating; no cell wall so antibacterials have no effect on virus bacteria are (many times) larger than viruses viruses are smaller than bacteria (100X) bacteria have more complex DNA viruses have simpler DNA bacteria mutate/multiply slower than viruses viruses mutate/multiply (much) faster than bacteria – resistance! bacteria vs virus

Ways in which antiviral drugs work Changes the cell membrane which prevents virus from entering cell. preventing viruses from using the host cell to multiply by 1.altering the genetic material or 2.preventing enzyme activity of the host cell . preventing the viruses from leaving the cell after reproducing inside the host cell.

Viral infections are harder to treat because… viruses mutate much more quickly so: they can adapt to drugs (new flu vaccine every year) or they can evade human immune system response (antibodies) bacteria are more complex and thus can be targeted in more ways - viruses lack subunits/functions which are normally targeted by antibacterials e.g. cell walls. bacteria can be killed or their actions reduced by simple chemical agents but viruses cannot be killed (only stopped reproducing) and must be targeted on genetic level different types of bacteria employ similar metabolic processes and thus can be targeted by common antibacterials whilst each kind of virus usually requires a specific drug.

AIDS (is a retrovirus – genetic material is in the form of RNA – not DNA) AIDS is syndrome caused by HIV which invades T4 cells which are a type of white blood cell (part of immune system). Virus binds to receptor proteins and penetrates the cell HIV releases RNA into the cell and uses the cell to make viral DNA Viral DNA integrates into the cell’s own DNA and replicates when the cell divides Virus is produced within the cell wall, and released when the host cell dies.

AIDS HIV viruses can mutate rapidly – so many strains Treatment of AIDS is problematic because HIV viruses can mutate rapidly – so many strains HIV viruses have similar metabolism to the metabolism of the host cell so any drug could also damage host cell antiretroviral drug targets are white blood cells which meant to protect us against other pathogens HIV lies dormant for a while so immune system is not responding socioeconomic: high price of antiretroviral drugs, access to drugs sociocultural issues: discrimination, stigma, religion

Examples of Viruses