Introduction to Viruses Flashcards
First virus?
Tobacco mosaic virus
Basic properties of viruses
Small (filterable), consist of protein, nucleic acid (sometimes lipid and carbohydrates), obligate parasites that utilize host cell machinery for their reproduction.
Are all viruses enveloped?
No, HIV is. Adenovirus is not.
Group I viral genomes
DNA, double stranded. Papovavirus, adenovirus, herpes virus, etc.
Group II viral genomes
Single stranded DNA (polarity + or -), parvovirus
Group III viral genomes
Double stranded RNA
Group IV viral genomes
Single stranded RNA (polarity +)
Group V viral genomes
Single stranded RNA (polarity -)
Group VI viral genomes
Single stranded RNA, replicated via DNA (reverse transcriptase), polarity +
Are viruses observed directly?
No, look for signs of virus like cytopathic effect, inclusion body formation, or hemadsorption
How to viruses work?
Free particles in tissue or environment inject their genetic material into a host cell, viral genome is replicated and transcribed. Viral mRNAs are translated and proteins are processed. Particles assemble inside host, then burst or bud to exterior.
Routes of viral infection
Oral/fecal, respiratory, transcutaneous, sexual, contact with infectious bodily fluid.
Persistent viruses
Can stay in the host without being cleared.
Most effective way to combat viral infection?
Vaccines
Inactivated vaccines
Killed viruses, elicit antibody responses. No chance of infecting the vaccinee. May not provide lifelong immunity.
