Chapter 7

Describe and contrast the multiplication of bacteriophages versus animal viruses.

Bacteriophage multiplication cycle: • Adsorption—attachment to cell • Penetration—entry into host cell • Assembly—copies of phage components replicated in host, maturation of newly formed phage, release of mature phages from host cell Animal virus multiplication: • Adsorption—attachment to cell • Penetration into host cell • Uncoating—envelope and capsid are removed and viral genome is released, synthesis and replication of viral components, assembly of complete virions, exit/release of virions from host cell

Describe host cell damage resulting from viral infections.

Cytopathic effects, physiological effects, biochemical effects, genotoxic effects.

A fully assembled virus is called a(n) ___________.

virion

Kaposi's sarcoma is caused by human herpesvirus number __________.

8

Name and describe the different morphological types of viruses.

Helical—coiled shape Icosahedral—capsids are 3-dimensional figures with 12 corners; 20 triangular faces and 30 edges Enveloped—have viral envelope surrounding nucleocapsid Complex—have various-shaped capsids (not icosahedral) along with other structures, such as tails

Discuss the two methods of viral classification.

International Committee on Taxonomy of Viruses (ICTV)—groups based on properties such as type of nucleic acid, presence of envelope along with others such as host, capsid shape, immunological properties, and disease caused. Hierarchy is: order, family, subfamily, genus, species. Baltimore Classification System—placed into one of seven groups based on relationship between viral genome and mRNA

Members of picornaviridae are __________ viruses.

RNA

Group VI viruses according to the Baltimore classification system include the families Metavirdae, Pseudoviridae, and _____________.

Retroviridae

Explain and discuss the structure and pathogenicity of sub-viral agents.

Viroids—circular ssRNA genome, no protein coat; common plant pathogens. • Virusoids (satellites)—circular, ssRNA genome with ribozyme activity. To replicate they require that the host cell is infected with specific helper virus; generally plant pathogens, but are similar to hepatitis D virus. • Prions—proteins that become abnormally shaped and when they come in contact with normal proteins they transform them into an abnormal shape; associated with a variety of neurodegenerative diseases.

The correct sequence of stages in the multiplication of animal viruses is: a. Adsorption, penetration, uncoating, replication, assembly, release b. Penetration, adsorption, assembly, uncoating, replica-tion, release c. Adsorption, uncoating, penetration, replication, assembly, release d. Penetration, uncoating, adsorption, replication, assembly, release

a. Adsorption, penetration, uncoating, replication, assembly, release

A persistent infection that is not lytic but productive is called a _____ infection. a. Chronic b. Latent c. Slow d. Transforming

a. Chronic

Which of the following viruses belong to the family Herpesviridae? a. Epstein- Barr virus b. Poxvirus c. SARS-CoV d. HIV

a. Epstein- Barr virus

A phage in a repressed stage is referred to as a( n): a. Antiphage b. Prophage c. Virulent phage d. Latent phage

b. Prophage

Viral capsomeres are composed of subunits called: a. Envelopes b. Protomeres c. Capsids d. Nucleoids

b. Protomeres

A virus that infects bacteria is referred to as a(n) ___________.

bacteriophage

All of the following are cytopathic effects as a result of a viral infection except: a. Altered shape b. Lysis c. Change in antigens d. Membrane fusion

c. Change in antigens

The correct hierarchical order for virus classification is: a. Order, genus, family, subfamily, species b. Species, genus, family, subfamily, order c. Order, family, subfamily, genus, species d. Genus, order, family, subfamily, species

c. Order, family, subfamily, genus, species

Transmissible spongiform encephalopathies are caused by: a. Flaviviruses b. Virusoids c. Prions d. Orthomyxoviruses

c. Prions

Viruses can infect: a. Plants b. Bacteria c. Animals d. All organisms

d. All organisms

RNA viruses belong to which of the following groups according to the Baltimore classification system? a. I, II, III b. II, III, IV c. I, IV, V d. II, IV, V

d. II, IV, V