Lecture 1

Question 1

What is the most infectious virus that exists? Out of 500 people, how may would be infected?

Answer 1

The measles virus, it is extremely contagious. Thirty-four would be infected.

Question 2

How is the measles virus transmitted? How can its transmission be prevented?

Answer 2

Transmitted via aerosols. It can be prevented through vaccination.

Question 3

Although there is a vaccine for the measles virus, geographically, where is it still a major problem?

Answer 3

In certain parts of South America and Africa.

Question 4

Who is most likely to contract the highly infectious measles virus? What did 94% of infected individuals have in common?

Answer 4

People who are unvaccinated. 94% of infected individuals were unvaccinated.

Question 5

When and where was the most recent measles virus outbreak?

Answer 5

In Indiana, the largest outbreak since 1996. Cost $168,000 to contain. The outbreak was due to a lack of vaccination due to fear of adverse effects from the vaccine.

Question 6

What information can be taken from the most recent measles outbreak?

Answer 6

People are not getting vaccinated. Vaccines work! 94% of the people who became infected with measles were unvaccinated.

Question 7

What are three examples of the impact of viruses on the world?

Answer 7

Outbreaks of the measles virus, of H1N1, and of ebola.

Question 8

At what point can a virus function as a virus?

Answer 8

After replicating in the living host cell

Question 9

How many deaths did the H1N1 influenza outbreak in Alberta cause at Christmas 2013?

Answer 9

10

Question 10

What virus is everyone likely infected with for life?

Answer 10

The herpes virus

Question 11

In what way do we consume viruses daily?

Answer 11

Insect viruses on vegetables

Question 12

How many viruses are there in one teaspoon of ocean water?

Answer 12

~5 million viruses

Question 13

What is calicivirus?

Answer 13

A virus that causes enteritis and rashes in whales. Whales may excrete 10^13 viral particles daily.

Question 14

What are HERVs?

Answer 14

Human endogenous retroviruses. HERVs integrate themselves into our genome. Approximately 10% of our DNA is derived from retroviruses.

Question 15

Where do HERVs come from?

Answer 15

They are remnants of past viral infections that occurred millions of years ago, but are no longer infectious.

Question 16

Do most viruses that infect us cause disease? Why or why not?

Answer 16

No. This is because we have defenses that protect us from them.

Question 17

What are the three defenses that humans have against viruses?

Answer 17

1. Intrinsic (smallest barrier) including the skin and physical barriers.
2. Innate immune system (middle sized barrier).
3. Adaptive immune system (largest barrier).

If a virus crosses all three of these barriers it will kill us.

Question 18

Name three instances in which the presence of a virus was beneficial.

Answer 18

1. Caterpillar-wasp relationship
2. Virus helping a fungus
3. Breaking of tulip pigment

Question 19

What is Curvularia protuberata? Explain its relationship with the curvularia thermal tolerance virus (CThTv).

Answer 19

Curvularia protuberata is a fungus that is required for the survival of Dichanthelium lanuginosum (plant). This plant grows at Yellowstone National Park in Wyoming, US, which is a location full of hotsprings, with soil of temperatures higher tham 50 degrees Celsius.

Although Dichanthelium lanuginosum can grow at temperatures higher than 50 degrees, it requires the fungus Curvularia protuberata, which cannot. The virus Curvularia thermal tolerance virus (CThTv) allows for the fungus to grow at these temperatures, permitting the survival of Dichanethlium lanuginsum.

Question 20

What virus permits a wasp to lay its eggs in a caterpillar? How does it do so?

Answer 20

The polydnavirus infects wasps. The polydnavirus carries wasp genes which suppress the innate immune response of the caterpillar. When a wasp deposits its eggs into the caterpillar, Polydnavirus virions are also deposited. Without the Polydnavirus the caterpillar’s innate immune system would kill the eggd, preventing their development.

Question 21

What was Tulipomania?

Answer 21

The first documented economic crisis. It occured following the bubonic plague and freedom from Spain in the 1600s in Holland, when the wages of the survivors increased.

Each single tulip bulb costed 3,000 guilders. It was known as a “broken tulip” because the pigment changed. People invested a lot of money in it, but the market crashed.

Tulip breaking was caused by a polyvirus (TBV), which interferes with pigment synthesis.

Question 22

What are the six major themes of virology?

Answer 22

1. Viruses package their genome in a particle called a virion.
2. They use this particle to transfer their genome.
3. The genome contains information to initiate and complete the viral life cycle.
4. The genome is essential to ensure long-term survival in the host.
5. Viral genomes are obligate molecular parasites. They can only function in a living host cell.
6. Viruses must make mRNA to be translated on the host ribosome.

Question 23

How have knowledge of viruses increased our overall knowledge?

Answer 23

They have helped us to learn how the host functions, as well as how the virus functions.

Question 24

Are viruses smart?

Answer 24

No. They just replicate and replicate and make a lot of everything.

Question 25

Do viruses grow?

Answer 25

No, they just replicate. They assemble their proteins into a virion, which remains the same size.

Question 26

What would happen if a virus always killed the host?

Answer 26

There would be no more hosts.

Question 27

What would happen if the host always killed the virus?

Answer 27

There would be no more viruses.

Question 28

How long have viruses existed for?

Answer 28

Over 250 million years. This is known by sequencing techniques.

Question 29

Why did the ancient Roman Emporer Tiberius ban kissing in public?

Answer 29

Because the herpes virus was being transmitted

Question 30

What was the first documented case of a virus?

Answer 30

In ancient Rome, the herpes virus was known as “to creep or to crawl”. Caused creeping and crawling lesions on the face.

Question 31

What did Ivanovsky and Beijerinck discover?

Answer 31

They discovered the Tobacco Mosaic Virus (TMV). They crushed TMV leaves and filtered it through a 0.2 micron filter, knowing that bacteria would not be able to pass through the filter. The infectious agent (virus) passed through the filter. The infectious agent was not able to “grow” on its own without a living host (the tobacco). They called it a “virus”.

Question 32

What did Loeffler and Frosch discover?

Answer 32

In 1898 they discovered the first animal virus. The virus caused foot and mouth disease. Ivanovski’s and Beijerinck thought that viruses were liquid, Loeffler and Frosch discovered that it was a particle. They discovered it by attempting to pass it through a 0.2 micron filter, but it wasn’t filterable like Ivanovski’s and Beijerinck virus. A micron is one millionth of a meter.

Question 33

How can viruses be viewed?

Answer 33

Through an electron microscope.

Question 34

Which virus is large enough to be seen with a light microscope?

Answer 34

The Mimivirus. It does not pass through a 0.2 micron filter, and is a parasite to an Amoeba.