Download Viral Reproduction Demonstration Outline

Cornell Institute
for
Biology Teachers
Title
Viral Reproduction and Budding Demonstration # 1
Modified from CIBT (EB-97) authors Patricia Nolan Bertino and James Blankenship
Author
CIBT EB-97
Patricia Nolan Bertino, Scotia-Glenville High School (retired), Scotia, NY
Demo # 1 Viral Reproduction Teacher Section
Page 1
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008
Appropriate
Level
This activity is appropriate middle and high school students.
Objectives
After viewing this activity, students should be able to:
1. Describe how a virus replicates inside a host cell
2. Describe how an infected cell undergoes lysis and releases newly
formed viruses.
3. Distinguish between an enveloped virus and a non-enveloped virus.
4. Explain how a virus spreads from infected cells to healthy cells
5. Relate the balloon simulation of viral replication to a the replication
of HIV within an infected host
Materials
4 Medium-sized balloons of the same color (host cell)
Scissors
4 5X8 cards Cut up pieces of papers inserted into balloon (new viruses)
4 Pins used to pop the balloons
8 Styrofoam balls (or ping pong balls) to represent HIV
2 gallon-sized zipped-lock baggie to represent the host cell membrane
4 rubber bands
HHMI DVD entitled: 2000 and Beyond: Confronting the Microbe Menace
HHMI DVD entitled: AIDS: Evolution of an Epidemic
( Or connect to HHMI website www.biointeractive.org )
Safety
Do not use latex balloons if anyone in the class has a latex allergy.
Objectives
.
This demonstration takes 15 minutes.
Time
CIBT EB-97
Demo # 1 Viral Reproduction Teacher Section
Page 2
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008
Abstract
A balloon filled with small pieces of cut-up papers is used to simulate how a
host cell infected with a virus may later “explode” or undergo lysis and release
many copies of the virus attacking healthy cells.
This is an excellent demo to describe enveloped viruses. HIV reproduction is
described in terms of budding out of the host cell. As the host cell produces
more viruses, some of the newly synthesized HIV will bud through the cell
membrane. In doing so, the newly synthesized virus does not cause a complete
lysis of the cell, but instead will carry part of the lipid cell membrane around the
virus forming an envelope. Because the virus is enveloped in the host’s cell
membrane, it is more difficult for the immune cells to recognize the virus.
To demonstrate an enveloped virus such as HIV, place eight Styrofoam balls
inside of a large zipped locked baggie. The Styrofoam balls represent newly
synthesized HIV. To show how the newly formed HIV buds out of the host cell,
wrap rubber bands between the zipped locked bag and four of the Styrofoam
balls that are located inside of the baggie.
Procedure
Advance Preparation
Infected Host cells
1. Select 4 medium-sized balloons all the same color and shape to
represent host cells.
2. Cut a 3X5 card into small pieces of paper to be used as viruses.
3. Stretch the opening of a deflated balloon and insert the cut pieces of the
cut up pieces of the 3X5 card into the open mouth of the balloon.
4. Inflate the balloon and tie it off.
5. Repeat steps 2-5 so that you have a total of 4 inflated balloons
(infected host cells) all containing the paper pieces (virus)
Budding virus from an infected host cell
6. Place one ball into a gallon-sized zip-locked baggie and seal
This represents a host cell infected with one virus
7. Place the remaining 7 balls into a different gallon-sized zip-locked
Baggie. This represents an infected host cell with 7 virus particles.
8. Using the baggie containing the 7 balls (viruses), wrap a rubber band
over the baggie and one of the balls (virus). Wrap a rubber band over the
baggie and the ball to demonstrate an enveloped virus.
9. Repeat this for three more of the balls (viruses) inside the baggie.
When finished you should have 4 enveloped viruses inside the host cell
(baggie) and 3 viruses not enveloped.
Demonstration
1. Ask students to try to explain why the symptoms of a viral infection such
as a cold seem to intensify over a period of several days and ultimately
disappear.
CIBT EB-97
Demo # 1 Viral Reproduction Teacher Section
Page 3
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008
2. Hold the inflated balloon over the head of a student. Explain that the
balloon represents a viral infected host cell in their body. Each student in
the class represents healthy cells within the body. Using a pin, pop the
balloon releasing all of the “paper” viruses inside of the “balloon” or host
cell. Check to see how many “students” or healthy cells are now infected.
Ask the newly infected cells to stand. Ask students to relate this
demonstration to someone just exposed to the cold virus and the progression
of symptoms.
3. Give the 3 other inflated balloons (infected host cells) filled with paper to 3
of the newly infected “students” or cells along with a pin. Ask the students
to stand and hold the balloon over their heads. On the count of three, each
of the infected cells (students) will pop the balloon representing lysis of
the infected cell.
4. Observe how the virus continues to spread to other healthy cells in the area.
Ask the newly infected “students” or host cells to please stand along with any
previously infected host cells.
5. Ask students to predict what happens to the host if the virus is not
eliminated from the host.
6. Ask the students to brainstorm ideas on how the body fights a viral infection
enabling a person to stop exhibiting symptoms of the virus.
7. Show the HHMI animation entitled: “ Viral Life Cycle”
8. Show the students the one large baggie (host cell) containing the one ball
(virus). Ask the students to summarize from the animation what happens
in the host cell that results in an increase in the number of viruses inside
of the host cell.
9. Show the students the model of the budding enveloped viruses from an
infected host cell. (Large baggies containing the 7 viruses: 4 budding and
3 non-budding viruses.)
10. Ask students to describe how a virus forms an enveloped virus.
11. Have students compare the body’s ability to seek and destroy an
enveloped virus versus a non-enveloped virus.
12. Introduce the idea of viral latency. Use the Herpes virus as an example
of a virus that may infects and then becomes latent for varying amounts
of time before another outbreak of symptoms. Ask students to
hypothesize as to what happens to the virus during this latency period.
CIBT EB-97
Demo # 1 Viral Reproduction Teacher Section
Page 4
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008
Further Study
Ask students to elaborate on this model and create a model that would
demonstrate how specific viruses will only invade specific host cells.
This model could be a three-dimensional model or graphic model presented in
the form of a PowerPoint presentation.
References
HHMI animation: Viral Life Cycle (1 min. 8 sec.)
HHMI Holiday Lecture; Infectious Disease: 2000 and Beyond:
Confronting the Microbe Menace
Hour 1 DVD Chapter 13 animation: Viral Infection
Additional
Reference for
Instructors
HHMI Holiday Lecture Infectious Disease: 2000 and Beyond: Confronting
the Microbe Menace
Hour 1 “Microbe Hunters: Tracking Infectious Agents”
Chapter 10: What are Viruses?
Chapter 12: How does a Virus Affect a Cell?
Hour 4 “ Emerging Infections: How Epidemics Arise”
DVD Chapter 20 Recombination of Viral RNA in a Host Cell
(3 min. 04 sec)
Animation: Recombination of Viral Genome (3 min. 5 sec)
HHMI Holiday Lectures AIDS Evolution of an Epidemic 2007
Hour 2 add title of hour 2 DVD chapter 16 HIV Life Cycle Part 1
CIBT EB-97
Demo # 1 Viral Reproduction Teacher Section
Page 5
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008
CIBT EB-97
Demo # 1 Viral Reproduction Teacher Section
Page 6
©1997 Cornell Institute for Biology Teachers, Ithaca, NY 14853. Distribution of this laboratory exercise is permitted if (i) distribution
is for non-profit purposes only, (ii) this copyright notice appears on each copy. Lab issue/rev. date: 8/31/97 revised 3/12/2008