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Block 6 - week 4 > Non-enveloped DNA viruses - Verma > Flashcards

Non-enveloped DNA viruses - Verma Flashcards

1
Q

Describe Adenoviruses.

A
  1. non-enveloped DNA virus
  2. more than 50 different serotypes
  3. causes upper and lower respiratory tract diseases such as pharyngitis, conjunctivitis (pink eye), common cold and pneumonia
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2
Q

Describe some diseases caused by Adenoviruses.

A
  1. types 4 and 7 - cause acute respiratory disease in all ages
  2. types 8,19 and 37 - causes kerato-conjunctivitis in adults
  3. types 40 and 41 - cause acute gastroenteritis in infants and young children
  4. types 3 and 7 - cause fever, pharyngitis, conjunctivitis and cervical adenopathy in all ages
  5. causes pneumonias and common cold in all ages
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3
Q

Describe the pathogenesis of Adenoviruses.

A
  1. spread by aerosol, close contact or fecal-oral route
  2. infects epithelial cell lining of oropharynx, respiratory and intestinal tract and causes cytotoxic damage
  3. antibody is important for resolving infection
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4
Q

How is Adenovirus infection diagnosed and treated?

A
  1. identification by culture, direct antigen detection and PCR.
  2. no specific antiviral therapy.
  3. hand washing prevents spread.
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5
Q

Describe Human Papillomaviruses.

A
  1. non-enveloped DNA virus
  2. 100 different types
  3. HPV types 16 and 18 are the most aggressive and can cause carcinoma of the cervix, penis and anus
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6
Q

Describe the pathogenesis of Human Papillomaviruses.

A
  1. HPV causes papillomas - benign tumors of squamous cells - except types 16 and 18
  2. virally encoded genes E6 and E7 are associated with carcinogenesis
  3. E6 and E7 inactivate the tumor suppressors p53 and pRb
  4. HPV 1-4 - cause skin and planter warts.
  5. HPV 6 and 11 - cause anogenital warts.
  6. HPV 16 and 18 cause carcinoma of the uterine cervix, penis and anus.
  7. HPV 6 and 7 also causes benign head and neck tumors or laryngeal papilloma in young children and HIV infected patients.
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7
Q

How are Human Papillomaviruses spread?

A
  1. HPV very resistant to inactivation
  2. spread through breaks in the skin/ sexual intercourse, infant passing through active infection in birth canal
  3. HPV is most prevalent sexually transmitted infection in the world
  4. HPV 16, 18, 31, 45 are high risk and HPV 6 and 11 are low risk
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8
Q

How is HPV infection diagnosed?

A

Microscopic examination, DNA molecular probes, PCR.

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9
Q

How is HPV infection treated?

A
  1. liquid nitrogen, surgical removal or salicylic acid is used for skin warts.
  2. genital warts treated with Podophylin, interferon, Cidofovir.
  3. vaccine - Gardasil, a recombinant vaccine against 4 HPV types - 6,11, 18 and 16.
  4. vaccine - Cervarix - against types 16 and 18.
  5. prevent by avoiding contact and using condoms.
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10
Q

Describe Parvovirus.

A
  1. non-enveloped ssDNA virus
  2. only one serotype - B19
  3. virus replicates in the nucleus
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11
Q

What disease is caused by Parvovirus?

A
  1. Erythema Infectiosum - also called Slapped cheek syndrome and Fifth disease.
  2. presents with bright red rash on cheeks with low grade fever, runny nose and sore throat in children.
  3. B19 can cause aplastic anemia in those with Sickle Cell disease.
  4. can cause arthritis of small joints in adults.
  5. infection during first trimester of pregnancy can cause fetal death.
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12
Q

How is Parvovirus spread?

A

Transmitted by respiratory route.

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13
Q

How is Parvovirus diagnosed and treated?

A
  1. Detection of IgM antibody
  2. Fetal infection - PCR of amniotic fluid.
  3. No specific treatment or vaccine.
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14
Q

Name 5 childhood diseases that present with rashes.

A
  1. fifth disease/erythema infectiosum
  2. measles
  3. rubella
  4. scarlet fever
  5. roseola
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15
Q

What are two viruses of the family Polyomaviridae that are clinically important?

A
  1. JC virus
  2. BK virus
    * SV40, a monkey virus can infect human cells also
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16
Q

Describe JC virus.

A
  1. non-enveloped DNA virus
  2. can cause progressive multifocal leukoencephalopathy or PML - a fatal demyelinating disease of white matter involving multiple areas of the brain.
  3. symptoms - visual field disturbances progressing to blindness, dementia, coma and death (usually within 6 months) - early signs are speech and vision abnormalities.
  4. occurs primarily in AIDS patients and other immunodeficient patients.
  5. virus persists in kidney cells and is excreted in urine and can also become latent in lungs and lymphoid organs.
  6. spread by respiratory tract early in childhood and reaches 70-80% seroprevalence in adults.
17
Q

Describe BK virus.

A
  1. non-enveloped DNA virus
  2. widespread infection
  3. can cause nephropathy and graft loss in immune suppressed renal transplant patients
  4. virus persists in kidney cells and is excreted in urine.
18
Q

How is infection with BK and JC virus diagnosed and treated?

A

PCR of cerebrospinal fluid sample. There are no specific treatments but cidofovir might be beneficial.

19
Q

What are prions?

A

Unconventional slow viruses that cause spongiform degenerative disorders of the brain.

20
Q

Name two prion-mediated diseases that are clinically important.

A
  1. Kuru

2. Creutzfeldt-Jakob disease

21
Q

What is the causative agent of Kuru and CJD?

A

Prions are the causative agent. These are proteins that lack nucleic acids. They are very stable and resistant to disinfection and have very long incubation periods.

22
Q

Describe Kuru.

A
  1. CNS disease of the Fore tribe of New Guinea
  2. transmitted by ritual cannibalism of diseased tribesmen - practice now stopped
  3. incubation period can exceed 50 years
  4. causes neurodegeneration
23
Q

Describe CJD.

A
  1. A progressive neurodegenerative disease that causes dementia and ataxia
  2. has a long incubation - onset 50-70 years old
  3. has three types
24
Q

Describe the 3 types of CJD.

A
  1. Sporadic - no known cause, possibly a new mutation in somatic cells
  2. Iatrogenic - spread through use of contaminated medical devices and through contaminated corneal grafts
  3. New Variant - spread by ingestion of bovine spongiform encephalopathy contaminated beef

Block 6 - week 4 (9 decks)

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