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MICR2209 > 10 - DNA Viruses > Flashcards

10 - DNA Viruses Flashcards

1
Q

Herpes viruses

A
  • Large dsDNA genomes encoding 100-200 genes
  • All herpesviruses are enveloped icosahedral viruses
  • Induce latent infections in humans
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2
Q

Subfamilies of herpesviruses

A
  • Alpha subfamily (neurons and epithelia)
  • Beta and gamma subfamilies (leukocytes and epithelia)
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3
Q

Alpha subfamily of herpesviruses

A
  • Herpes simplex virus type 1
  • Herpes simplex virus type 2
  • Varicella zoster
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4
Q

Beta and gamma subfamilies of herpesviruses

A
  • Human cytomegalovirus
  • Epstein Barr virus
  • Human herpes virus 6-8
  • B virus
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5
Q

Where does HSV-1 persist in a latent state

A

Trigeminal ganglia and is reactivated by trauma, fatigue, sunlight, emotional stress

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6
Q

Herpes simplex virus type 1 (HSV-1)

A
  • cold sore, is a recurrence of the first or primary infection
  • Herpetic whitlow is HSV infection of fingers and thumbs (often caused by autoinoculation secondary to genital herpes and health care workers)
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7
Q

Herpes simplex virus type 2 (HSV-2)

A
  • Associated with genital herpes
  • Infects epithelial cells of external genitalia, rectum and adjacent skin
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8
Q

Neonatal herpes

A
  • HSV-2 can be transmitted to newborns during delivery
  • Results in blindness and neurological disease in babies.
  • Caesarian delivery recommended
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9
Q

Varicella Zoster Virus (VZV)

A
  • Receptor is mannose-6-phosphate
  • Acquired by respiratory route (airborne)
  • Vesicles similar to those produced in HSV are formed, and form lesions, but unlike the HSV lesions are not infectious
  • Shingles is reactivation of chickenpox
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10
Q

2 main syndromes caused by VZV

A
  • Varicella (chickenpox)
  • Zoster (shingles)
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11
Q

Shingles

A
  • the virus becomes dormant in the dorsal root ganglion but can also affect any sensory nerve
  • Can be reactivated to cause shingles
  • Usually only one such event in a lifetime (elderly or immunocompromised)
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12
Q

Example of drug to treat HSV and VZV

A

Acyclovir

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13
Q

Human cytomegalovirus (HCMV)

A
  • 80% prevalence
  • Infection is initiated through a nonspecific interaction with heparan sulfate proteoglycans
  • Life long
  • Interferes with host immune functions including antigen presentation, cytokine production, and natural killer cell activity
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14
Q

Cytomegalo

A

Enlarged cell

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15
Q

Risk groups for HCMV

A
  • Organ transplant recipients
  • Immunocompromised (especially AIDS patients)
  • Newborns
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16
Q

Epstein Barr virus (EBV)

A
  • Causes infectious mononucleosis (glandular fever/kissing disease)
  • Infects epithelial cells lining the throat.
  • New virus particles infect memory B cells, which rapidly proliferate and take on an atypical appearance that is useful in diagnosis
17
Q

How does EBV spread

A

Present in oropharyngeal secretions and therefore is spread by mouth-to-mouth contact or shared drinking glasses

18
Q

Manifestations of EBV

A

Enlargement of lymph nodes and spleen, sore throat, fever, headache, and general tiredness and weakness

19
Q

Severe diseases caused by EBV

A
  • Burkitt’s lymphoma
  • nasopharyngeal carcinoma
20
Q

Burkitt’s lymphoma

A
  • Tropical africa
  • Coinfection with malaria, or immunodeficiency
  • Those infected with HIV
21
Q

Human papilloma virus (HPV)

A
  • Nonenveloped icosahedral, small dsDNA viruses
  • Infect epithelial cells through micro-abrasions causing genital warts and/or cancerous lesions
  • Spread by direct contact and by autoinoculation via scratching
22
Q

How many strains of HPV are there and how many are transmitted sexually

A

> 170 strains with >40 transmitted sexually

23
Q

HPV16 and 18

A

Responsible for most cervical cancers in women

24
Q

HPV 6 and 11

A

Responsible for genital warts and laryngeal papillomatosis

25
Q

how are early pre cancerous changes of HPV detected

A

Via pap smears

26
Q

Nona-valent human papillomavirus vaccine

A
  • 9 HPV strains, including 6, 11, 16 and 18
  • School-based National HPV Vaccination Programs (Targets young adolescent)
27
Q

Hepatitis B virus (HBV)

A
  • dsDNA virus
  • Infect liver cells (hepatocytes) and causes hepatitis (inflammation of the liver)
  • Most infections are acute and the virus is cleared by immune response
28
Q

Transmission of HBV

A
  • Parenteral transmission
  • Highest concentration of virus found in blood (lower conc. in semen, vaginal fluid)
  • 50% of acute HBV is acquired sexually
  • Needlestick injury, needle sharing, tattooing, acupuncture
29
Q

Clinical features of HBV

A
  • symptomatic acute
    hepatitis: fatigue, malaise, fever, abdominal
    pain, icterus (jaundice), pruritus (itching)
  • Usually asymptomatic in neonates and young
    children
30
Q

Hepatitis B replication

A
  • Virus enters the cell
  • Capsid disassembly
  • Viral relaxed circular DNA
    enters nucleus of cell
  • CCC-DNA created
  • Transcription to RNA occurs
  • RNA is packaged up into a
    new capsid
  • New virus is created
  • Virus leaves cell.
31
Q

What happens if HBV is not cleared

A
  • Virus continues to replicate and patient becomes chronic carrier (continued HBV infection 6 months after infection)
  • Associated with development of cirrhosis (liver damage and scarring) and liver cancer (hepatocellular carcinoma)
32
Q

Prevention of perinantal HBV transmission

A

providing hepatitis B immune globulin and hepatitis B vaccine to infants within 12 hours of birth

33
Q

Blood tests for HBV

A
  • Hepatitis B surface antigen (HBsAg) is detectable in blood soon after infection
  • Clearance of HBsAg from blood, and appearance of anti-HBs, indicates recovery
  • Persistence of HBsAg (> 6 months after infection), lack of anti-HBs, indicates chronic infection (carrier state)
34
Q

Polyoma virus JC

A

Fatal demyelinating disease of the CNS: progressive multifocal leukoencephalopathy (PML) in which oligodendrocytes are destroyed

MICR2209 (26 decks)

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