What do you know about Viruses?

• 1. What are the 5 most common viral infections?

• 2. Name 2 similarities between a virus and a bacteria?

• 3. Name 2 differences between a virus and bacteria.

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Top 7 most common viral diseases identified by CDC

• 1. Avian flu

• 2. Influenza

• 3. Genital Herpes

• 4. Hepatitis

• 5. Cervical cancer (Humanpapilloma virus)

• 6. Meningitis

• 7. HINI flu

FACTS

• 1. There are a million virus particles per milliliter of seawater – for a global total of 1030 virions! Lined up end to end, they would stretch 200 million light years into space.

• 2. Walter Reed discovered the first human virus, yellow fever virus, in 1901.

• 3. Over 1016 human immunodeficiency virus genomes are produced daily on the entire planet. As a consequence, thousands of viral mutants arise by chance every day that are resistant to every combination of antiviral compounds in use or in development

• 4. The first human influenza virus was isolated in 1933. In 2005, the 1918 pandemic influenza virus strain was constructed from nucleic acid sequence obtained from victims of the disease.

• 5.The biggest known viruses are mimiviruses, which are 400 nanometers (0.0004 millimeters) in diameter. The viral genome is 1,200,000 nucleotides in length and codes for over 900 proteins.

• 6. The smallest known viruses are circoviruses, which are 20 nanometers (0.00002 millimeters) in diameter. The viral genome is 1,700 nucleotides in length and codes for two proteins.

Virus: General characteristics

A strand of genetic material within a protein capsid.

Has a tail for attachment Lacks cell /organelles Cannot make proteins Cannot move Cannot replicate on their own Most viruses range in size from 5 to 300

nanometers.

Virus Origin

Viruses came from parts of cells.

Genetic material of viruses is similar to cellular genes.

Lytic Cycle

The host cell makes many copies of the viral RNA or DNA. Virus is assembled, destroys cell and gets out.

Lysogenic Cycle (hidden cycle)

Viral DNA inserts, or integrates into a chromosome in a host cell.

Infected cell will have the viral genes permanently.

Bacteria and Viruses

18.2 Viruses and Prions

Chapter 18

Bacteria and Viruses

Prions

Protein that can cause infection or disease is called a proteinaceous infectious particle, or prion.

Prions normally exist in cells.

Associated with diseases known as transmissible spongiform encephalopathies

Chapter 1

1. A

2. B

FQ 8

Smallpox has been eliminated worldwide and routine vaccination for the disease has stopped.

A. TrueB. False

1. A2. B3. C4. D

FQ 9

What type of virus inserts RNA and reverse transcriptase into cells?

A. adenovirus

B. bacteriophage

C. prion

D. retrovirus

1. A2. B3. C4. D

STP 6

For which virus is there not yet a vaccine?

A. HIV

B. polio

C. rabies

D. smallpox

1. A2. B3. C4. D

STP 7

What type of infection is caused by a virus that replicates by the lysogenic cycle?

A. active infection

B. passive infection

C. advanced infection

D. latent infection

Visualizing Viral Replication

Retrovirus Replication

Animation

Retroviruses

Viruses that have RNA instead of DNA for their genetic material

Retroviruses have a protein capsid.

Lipid envelope is obtained from the plasma membrane of a host cell