Virology 1

Question 1

Virus vs bacteria

Answer 1

Virus is always intracellular, no plasma membrane, no binary fission, never have both RNA and DNA, no ATP mechanisms, no ribosomes.

Question 2

Virus classification

Answer 2

Type of nucleic acid, strategy used for replication, morphology. Also according to species (ie Herpes simplex virus 1 and 2)

Question 3

General virus structure

Answer 3

Naked virus: Genome (DNA or RNA), Capsid, Nucleocapsid (genome + capsid), Capsomeres, glycoproteins. Enveloped viruses also have Envelope and Glycoproteins (more)

Question 4

Viral nucleic acids

Answer 4

DNA viruses: most dsDNA except for parvovirus (ssDNA) and hepadnavirus (partially dsDNA). RNA viruses: most are single stranded (except retroviridae): + sense or – sense (antisense). + sense RNA acts as mRNA in host to immediately start producing protein

Question 5

Viral envelope (where applicable)

Answer 5

Steal piece of membrane from plasma membrane, golgi or nucleus. Generally easier to inactivate with disinfectants (ie in a body fluid spill

Question 6

What is Tropism?

Answer 6

aka specificity. depends on receptor on host, pH, temp, regulation factors

Question 7

What else could a virus have in addition to the basics?

Answer 7

Enzymes for protein synthesis, replication; RNA polymerase; reverse transcriptase

Question 8

Categories of viral-host interactions

Answer 8

productive infection: replicates, many virions, host cell bursts (lytic infection). latent infection: viral genome persists but no replication = provirus. chronic infection: replicates w/o causing host cell lysis, stays around long time.

Question 9

What effects do viruses have on host cells?

Answer 9

Altered function, stimulate immune system (NK and Tc cells, AB), oncogenic transformation, apoptosis/necrosis, inhibit apoptosis, form syncytia

Question 10

Stages of disease

Answer 10

Incubation, prodrome (mild symptoms), illness, (death if responses fail), period of decline, convalescence

Question 11

Serological positivity

Answer 11

Blood test. Detect IgM for an agent means host has been exposed once. If you are exposed later you usually see an increase in IgG or IgA

Question 12

Medically relevant DNA viruses

Answer 12

Herpesviridae, Poxviridae, Adenoviridae, Papovaviridae, Parvoviridae, Hepadnavirus

Question 13

Medically relevant RNA viruses

Answer 13

Picornaviridae, Caliciviridae, Astroviridae, Togaviridae, Flaviviridae, Coronaviridae, Paramyxoviridae, Orthomyxoviridae, Rhabdoviridae, Filoviridae, Bunyaviridae, Arenaviridae, Reoviridae, Retroviridae