Classification and nomenclature of viruses

Question 1

The main criteria for the classification of viruses established by the International Commite on Taxonomy of viruses are:

Answer 1

1. the type and character of the viral genome
2. the strategy of viral replication
3. the morphology of the virion

Question 2

Families end in

Answer 2

-viridae

Question 3

subfamily

Answer 3

• deals with the complex interrelationships among member viruses in a family
• ends in -virinae

Question 4

genera and species

Answer 4

• the classification of genera and species within a family are based on criteria which include: host species, pathogenesis, nucleic acid homology and antigenic difference.
• ends in virus

Question 5

parvoviridae

Answer 5

• very small
• replication occurs in actively dividing cells and takes place in the nucleus
• form acidiophilic intranuclear inclusion bodies
• remarkably resistant

Question 6

papillomaviridae

Answer 6

• causes warts( proteins promote cell growth)
• small
• genome may be episomal or integrated into host cell DNA
• replicate in the nucleus
• stable in the environment

Question 7

Adenoviruses

Answer 7

• medium sized
• possess filament/ fibers
• fiber contains viral attachment proteins
• replicate in host cell nucleus
• produce basophilic intranuclear inclusion bodies
• cause latent infections

Question 8

Asfarviridae

Answer 8

• large virons
• replication occurs in the cytoplasm of host cell and soft ticks
• -produce intracytoplasmic inclusion bodies
• African swine fever

Question 9

Herpersviridae

Answer 9

• creep
• consist of three subfamilies
• replicate in the nucleus
• acidophilic intranuclear inclusion bodies
• fragile
• cytomegaly or syncytia
• life long persistance

Question 10

Poxviridae

Answer 10

• largest of all the viruses that cause disease in domestic animals
• complex in structure
• replication occurs in the cell cytoplasm
• eosinophilic intracytoplasmic inclusion bodies
• all produce skin lesions
• can survive for months to years

Question 11

Hepadnaviridae

Answer 11

• liver
• partially double-stranded and partially single-stranded DNA
• replicates in the nucleus of hepatocytes
• replication involves reverse transcriptase
• acute or chronic hepatitis

Question 12

Circoviridae

Answer 12

• smallest known virus of vertebrates and plants
• single-stranded DNA
• only replicates in the nucleus of dividing cells
• stable in the environment

Question 13

Picornviridae

Answer 13

• stable
• no inclusion bodies
• rapidly cytolytic
• multiple serotypes may produce same disease syndrome, with very little or no cross-protection between serotypes

Question 14

Caliciviridae

Answer 14

-cup
-stable in the environment
-no inclusion bodies
-+ sense RNA
-replication takes place in cell cytoplasm
-

Question 15

Togaviridae

Answer 15

• fragile
• no inclusion bodies
• +sense RNA genome
• enveloped
• replication in the cytoplasm
• infection of host cells is acute and cytolytic

Question 16

arteriviridae

Answer 16

• fragile
• (+) sense RNA/ ennveloped
• replication in the cytoplasm
• primary host cells are macrophages
• persistent infection

Question 17

Flaviviridae

Answer 17

• yellow
• enveloped/ (+) sense RNA
• replication occurs in the cytoplasm
• infection of vertebrate cells is cytolytic

Question 18

Reoviridae

Answer 18

• respiratory enteric orphan
• two to three layered capsids
• segmented
• double-stranded RNA genome
• genetic reassortment
• replication in the cytoplasm
• acidophilic, intracytoplasmic, perinuclear inclusion bodies
• moderate to stable in the environment

Question 19

Birnaviridae

Answer 19

• two segments of RNA/ double stranded
• kill cells they multiply in
• stable in the environment

Question 20

Coronaviridae

Answer 20

• crown
• envelope with club-shaped surface
• replication occurs in the cytoplasm
• narrow host range and readily establish persistent infections

Question 21

Paramyxoviridae

Answer 21

• large virion
• pleomorphic envelope
• (-) sense RNA
• penetrate host cell by fusion with the plasma membrane
• all member produce intracytoplasmic inclusions, but some produce intranuclear bodies
• produce syncytia or multinucleated giant cells
• some cause persistent infections

Question 22

Orthomyxoviridae

Answer 22

• pleomorphic virions
• segmented genome
• (-) sense single stranded RNA
• genetic reassortment
• replication takes place in the nucleus and the cytoplasm
• labile in the environment

Question 23

Rhabdoviridae

Answer 23

• bullet
• single-stranded (-) sense RNA
• replication occurs in the cytoplasm
• Negri bodies
• inactivated by UV light
• rabies

Question 24

Retroviridae

Answer 24

• diploid genome
• (+) sense/ single stranded RNA
• reverse transcriptase
• provirus
• host remain chronically infected
• labile viruses

Question 25

Bunyaviridae

Answer 25

• genetic reassortment
• tripple segmented
• replication occurs in the cytoplasm
• labile in the environment

Question 26

Bornaviridae

Answer 26

• (-) sense/single-stranded genome
• intranuclear inclusion bodies
• particular affinity for nervous tissues
• labile virion

Question 27

Astroviridae

Answer 27

• star
• (+) sense ssRNA
• five to six pointed stars on surface
• replicate in the cytoplasm
• no inclusion bodies
• moderately stable