D.5: ANTI-VIRAL MEDICATIONS
UNDERSTANDINGS
- Viruses lack a cell structure and so are more difficult to target with drugs than ____________________.
- Antiviral drugs may work by altering the cell’s __________________ material so that the virus cannot use it to ______________.
Alternatively, they may prevent the viruses from multiplying by blocking _________________ activity within the _________cell.
APPLICATION AND SKILLS
- Explanation of the different ways in which antiviral medications work.
- Description of how viruses differ from bacteria.
- Explanation of how oseltamivir (Tamiflu) and zanamivir (Relenza) work as preventative agents against flu viruses.
- Comparison of the structures of oseltamivir and zanamivir.
- Discussion of the difficulties associated with solving the AIDS problem.
NATURE OF SCIENCE
- Scientific collaboration – recent research in the scientific community has improved our understanding of how viruses invade our
systems.
1. BACTERIA AND VIRUSES
SIZE
STUCTURE
REPRODUCTION
BACTERIA
- 0.5 -5.0 micrometres
- easily observed with _________
microscope
- ______________-celled organisms
- contain single circular strand chromosome
of ______
- rigid cell ______and cell membrane
- _____________ to break down food and
build cell parts found in cytoplasm
- reproduce _________________from other
living cells
VIRUSES
-extremely small (20 to 300 ____)
-submicroscopic (i.e. ______________ microscope
must be used in order to study)
- central core of DNA or RNA surrounded by protein
coat called a capsid
- no cellular structure (i.e. no nucleus, cytoplasm or
cell membrane
- only capable of reproducing ___________ another
living cell using components [e.g. enzymes
(ribosomes)] of host cell
- do not __________ or _____________
2. TWO SPECIFIC ANTIVIRAL DRUGS (OSELTAMIVIR & ZANAMIVIR)
*For the most part, viruses, such as those causing polio, smallpox and yellow fever, are controlled via ____________________.
- Viruses lack a cell structure and so are more difficult to target with drugs than bacteria.
- Explanation of the different ways in which antiviral medications work.
*ANTIVIRAL DRUGS WORK PREDOMINATELY IN ONE OF TWO WAYS:
1. ALTERING THE HOST CELL’S __________________MATERIAL (i.e. its DNA) so that the virus cannot use it to multiply
2. By preventing the viruses from reproducing or escaping the host cell by BLOCKING _______________ ACTIVITY WITHIN
THE HOST CELL
INFLUENZA (FLU VIRUSES)
-Flu is caused by two main type of virus known as influenza A and B. They are ___________________ viruses and have
_______ as their genetic material.
-Flu viruses have specific ________________ on their surface, of which two play a key role in their __________ cycle.
SUMMARY:
PROTEIN ON VIRAL SURFACE
1. HEMAGGLUTININ (H)
*2. NEURAMINIDASE (N)
ROLE OF PROTEIN IN VIRAL LIFE CYCLE
– a glycoprotein that enables the viral particle to ‘________’ with the host cell
before it enters
– an ________________ that catalyzes a cleavage reaction which allows new
viral particles to ___________ from the ____________ cell to ___________
infection. The enzyme snips off a type of ______________molecule,
___________ acid, from glycoproteins on the surface of the host cell
_________________.
*The drugs, Tamiflu and Relenza, ____________the
action of the neuraminidase enzyme by occupying the
enzyme’s ____________ site – the site that that would
have been occupied by ____________ acid. Note the
similarity in structure between these synthetic drugs and
naturally occurring sialic acid.
.
oseltamivir (Tamiflu)
zanamivir (Relenza)
FUNCTIONAL GROUPS
- alkenyl
- ether
- primary amino
- carboxyamide
- ester
DRUG ACTION
-neuraminidase inhibitor
- explain
- orally
- some rare strains of flu have shown
resistance
- nausea, vomiting
- alkenyl
- ether
- primary amino
- carboxyamide
- carboxylic acid
- hydroxyl (3)
-neuraminidase inhibitor
STRUCTURE
ADMINISTRATION
RESISTANCE TO DRUG
COUNTER-EFFECTS
- inhalation
- no resistance reported
- possible asthma
3. AIDS (ACQUIRED IMMUNE DEFICIENCY SYNDROME)
(Syllabus - Be able to discuss the difficulties associated with solving the AIDS problem.)
The THREE MAIN REASONS why HIV is more challenging than other viruses to defeat:
REASON
1. HIV DESTROYS ________________
BLOOD CELLS/LYMPHOCYTES
(HELPER T-CELLS /
DESCRIPTION
– destroys the very cells in the _______________ system that should
be defending the body against the virus
2. HIV ________________ &
_________________ VERY RAPIDLY
- HIV can produce up to ______ new copies per day
– It is thought that there is more variation in HIV in a single patient
than the ________________ virus worldwide in a year. These
variations mean that the virus ‘escapes’ the immune response, so the
patient has to make a response to the new virus.
3. HIV OFTEN LIES_________________
WITHIN HOST CELL _______
- therefore immune system has nothing to respond to
- so even if HIV is eradicated from body, the __________________
FOR BUILDING more HIV viruses lies dormant sometimes for
years…could _________________ and start to spread virus again
OTHER ISSUES/ COMPLICATIONS:
- lack of health care, poor education, sociocultural issues
- high cost of anti-retroviral drugs
- a large number of those infected are unaware of infection…continue to infect others
- use of condoms is rejected in certain societies due to economic or religious reasons
YOUTUBE
1. ‘Why it’s so hard to cure HIV/AIDS’ (Janet Iwasa)