intro to virology Flashcards
All DNA viruses are double-stranded except
for
parvoviruses (they have have ssDNA)
All RNA viruses are single-stranded except
dsRNA reoviruses
Most DNA viruses are budded off the
nucleus
Most RNA viruses multiply in and are released
from the
cytoplasm
Viral infections range from _______ to life threatening
asymptomatic
Course of viral disease
invasion at portal of entry
and primary infection; some viruses replicate locally,
others enter the circulation and infect other tissues
Common manifestations
rashes, fever, muscle aches,
respiratory involvement, swollen lymph nodes
Body defenses
combined action of interferon,
antibodies, and cytotoxic T cells; frequently results
in lifelong immunity
2 types of persistent infections:
chronic infection and latent infections
Chronic infections
virus is detectable in tissue
samples, multiplying at a slow rate; symptoms mild or
absent
Latent infections
after a lytic cycle, virus enters a
dormant phase; generally not detectable, no symptoms;
can reactivate and result in recurrent infections
Animal viruses are categorized according to
nucleic acid, capsid, and presence or
absence of envelope
__ DNA families, __ RNA families
7,14
DNA viruses causing human disease
-Enveloped DNA viruses
– Nonenveloped DNA viruses
– Nonenveloped ssDNA viruses
enveloped dna viruses examples
poxviruses,herpesviruses,hepadnaviruses
poxviruses
-Produce eruptive skin pustules called pocks or pox,
that leave scars
• Largest and most complex animal viruses
• Have the largest genome of all viruses
• dsDNA
• Multiply in cytoplasm in factory areas
• Specificity for cytoplasm of epidermal cells and
subcutaneous connective tissues
smallpox
• First disease to be eliminated by vaccination
• Exposure through inhalation or skin contact
• Infection associated with fever, malaise,
prostration, and a rash
– Variola major – highly virulent, caused toxemia, shock,
and intravascular coagulation
– Variola minor – less virulent
Molluscum Contagiosum
in endemic areas, primarily an infection of children.
in US,most commonly a STD.
-Lesions are small, smooth macules in genital area
and thighs
-AIDS patients suffer an atypical form which
attacks the skin of the face and forms tumor-like
growths
treatment for molluscum contagiosum
: freezing, electric cautery, chemical
agents
Monkeypox in humans
skin pocks, fever,
swollen lymph nodes
Cowpox in humans
rare, usually confined to
hands; other cutaneous sites can be involved
