Parvo, Adeno, Poxviruses

Question 1

• smallest of the DNA viruses, about the size of a ribosome
• ssDNA
• inverted repeats at each end that hybridize to form hairpin loops
• plus and minus strands packaged into separate particles

Answer 1

parvoviruses

Question 2

parvoviruses?

Answer 2

B19 virus, adeno-associated virus

Question 3

parvovirus replication:

• infects mitotically active ________ cells
• assembled in the _____
• lysis

Answer 3

erythroid precursor

nucleus

Question 4

• replication of parvoviruses takes place in the _______ and cell must be in S phase
• uses single strand displacement model
• terminal sequences are used as ______
• specific cleavage of replicative intermediates, using _____ proteins

Answer 4

nucleus

primers

NS1

Question 5

• causative agent of childhood disease known as erythema infectiosum
• at risk: school age children
• incubation: 4-14 days
• 50% of infections are asymptomatic
• during prodromal period there is a mild fever, sore throat, malaise
• children develop characteristic slapped cheek rash

Answer 5

B19 virus Fifth’s disease

Question 6

adults infected with B19 suffer _________ rather than a rash, and can persist for weeks, months, or years

Answer 6

joint pains or arthritis

Question 7

symptoms of adult B19 fifth’s disease are associated with?

Answer 7

B19 antibody complexes

Question 8

B19 virus disease mechanisms:

• spread by?
• infects what type of cells?
• causes what type of disease?
• what is important for resolution of disease?

Answer 8

• respiratory and oral secretions
• mitotically active erythroid precursor cells in bone marrow, establishing lytic infection
• establishes viremia, can cross placenta, causing biphasic disease (initial related to viremia, later related to immune response)
• antibody

Question 9

complications of B19 virus?

Answer 9

1. transient aplastic crisis: abrupt cessation of red cell production in bone marrow
2. cell red cell anemia: chronic bone marrow suppression and anemia
3. hydrops fetalis: when pregnant woman infected with B19, kills erythrocyte precursors causing anemia and congestive heart failure, risk of fetal death 1-9%

Question 10

• requires coinfection with unrelated helper virus, either adenovirus or herpesvirus for productive replication
• establish latent infection by integrating specifically into chromosome 19 by homologous recombination
• not associated with tumor formation
• studied as potential vector for gene therapy

Answer 10

adeno-associated virus

Question 11

• non-enveloped icosahedral virus that has fibers at vertices
• linear ds DNA
• replication in nucleus
• basophilic intranuclear inclusion bodies

Answer 11

adenovirus

Question 12

common human diseaes caused by adenovirus?

Answer 12

acute respiratory illness, pharyngitis, gastroenteritis, conjunctivitis, pneumonia, keratoconjunctivitis, acute hemorrhagic cystitis, hepatitis

Question 13

incubation period of adenovirus?

Answer 13

1 week to 9 days

Question 14

rapid detection can be made by detection of adenovirus antigen from _______ aspirates and throat washings

Answer 14

nasopharyngeal

Question 15

adenovirus vaccine?

Answer 15

only for adult respiratory distress syndrome, live vaccine, given to armed forces

Question 16

• most complex and largest viruses that infect man
• linear ds DNA genome
• only viruses that exclusively replicate in cytoplasm
• virus encodes for all proteins necessary for mRNA synthesis, DNA synthesis

Answer 16

poxvirus

Question 17

• abrupt onset of fever, macular rash on third day, progress to vesicles which become pustular, ulcerated, scabbed, healed with scarring
• cell mediated immunity important, antibodies useless

Answer 17

smallpox

Question 18

• usually transmitted by direct contact with the animal
• single nodular lesion forms at point of contact
• lesions become granulomatous
• vesicular lesions usually form, regresses within 25-35 days

Answer 18

orf virus

Question 19

• nodular to wart like lesions, most commonly on trunk, genitalia, and proximal extremities
• incubation period 2 to 8 weeks
• inclusion bodies, self limiting and resolve

Answer 19

molluscum contagiosum