Flashcards in Virology 1 Deck (13):
Virus vs bacteria
Virus is always intracellular, no plasma membrane, no binary fission, never have both RNA and DNA, no ATP mechanisms, no ribosomes.
Type of nucleic acid, strategy used for replication, morphology. Also according to species (ie Herpes simplex virus 1 and 2)
General virus structure
Naked virus: Genome (DNA or RNA), Capsid, Nucleocapsid (genome + capsid), Capsomeres, glycoproteins. Enveloped viruses also have Envelope and Glycoproteins (more)
Viral nucleic acids
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
Viral envelope (where applicable)
Steal piece of membrane from plasma membrane, golgi or nucleus. Generally easier to inactivate with disinfectants (ie in a body fluid spill
What is Tropism?
aka specificity. depends on receptor on host, pH, temp, regulation factors
What else could a virus have in addition to the basics?
Enzymes for protein synthesis, replication; RNA polymerase; reverse transcriptase
Categories of viral-host interactions
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.
What effects do viruses have on host cells?
Altered function, stimulate immune system (NK and Tc cells, AB), oncogenic transformation, apoptosis/necrosis, inhibit apoptosis, form syncytia
Stages of disease
Incubation, prodrome (mild symptoms), illness, (death if responses fail), period of decline, convalescence
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
Medically relevant DNA viruses
Herpesviridae, Poxviridae, Adenoviridae, Papovaviridae, Parvoviridae, Hepadnavirus