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DNA Viruses Flashcards

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1
Q

What are the naked DNA viruses?

A

Parvovirus
HPV
Polyoma virus
Adenovirus

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2
Q

What are the envelope DNA virus?

A

Herpes virus
Poxvirus
Hepadnavirus (Hepatitis B virus)

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3
Q

What are the characteristics of the parvoviruses?

A

Smallest DNA viruses
Limited genetic resources, heavily rely on host
B19 and bocavirus cause human diseases
Bocavirus can cause acute respiratory disease

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4
Q

What is the mode of transmission of B19?

A

Contagious viral infection
Usually occurs during late winter and spring
Transmission by respiratory droplets or oral secretions
Mother to fetus during pregnancy
65% adults are seropositive by age 40

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5
Q

What is the epidemiology of B19?

A

Initially infects nasopharyngeal and bone marrow via viremia
The target cells are the erythroid precursor cells
Cytopathology is anemia and immune response
Immune response is responsible for rash and arthralgia
Prodromal period of 7-10 days
No symptoms to fever,sore throat, malaise, low hemoglobin

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6
Q

what are the characteristics of B19- fifth disease?

A

A common childhood exanthématique among 4-15 year old
Slapped-cheek syndrome- erythema infectiosum
Rash may spread to exposed skin (arms and legs)
Can cause still birth, severe anemia, hydrops fetalis

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7
Q

How is B19 diagnosis done?

A

Characteristic appearance of rash
Serology for B19 IgM/IgG
PCR for viral genome

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8
Q

What are the characteristics of HPV?

A

Over 100 serotypes
Causes lyric, chronic,latent and transforming infections
Most prevalent STI, transmitted also from fomites

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9
Q

What is the epidemiology of HPV?

A

Virus induces epithelial proliferation by inhibiting p53 or p105RB
Warts appear 1-6 months after infection but more rapidly in immuno compromised people
Warts induces cell growth in basal layers
No symptoms with warts or occasional burning pain
Virus shed with dead skins cells
Presence of enlarged keratinocytes with clear halos-Koilocytes
CD 8 T cells cause the wart to regress
HPV present in 99% of cervical cancers (HPV 16/18 in 70%)

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10
Q

What are the different HPV diseases?

A

Papillomas
Anogenital warts
Laryngeal papillomas
Cervical dysplasia and carcinoma

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11
Q

What are the characteristics of the papillomas?

A

Also called warts
Benign self limited proliferation on skin or mucous membranes
Develop over 3-4 months
Warts may be dome shaped, flat

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12
Q

What are the characteristics of anogenital warts?

A

Usually on external genitalia or perianal surface
Caused mostly by HPV 6 or 11(90%)
Rarely malignant in healthy individuals

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13
Q

What are the characteristics of head/neck tumors?

A

Oral papillomas caused by HPV 6 or 11
Laryngeal papillomas are benign solitary tumors by HPV 6 or 11
Laryngeal papillomas may be serious by obstructing airway in children infected at birth

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14
Q

What are the cervical dysplasia and carcinoma?

A

Usually asymptomatic but may result in slight itch
Warts may be soft,flat, raised and cauliflower shaped
May appear within weeks or months

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15
Q

How to diagnose HPV?

A

Hyperplasia and Pap smear showing koilocytes
DNA probes and PCR can confirm infection
Regular pap tests for women

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16
Q

What are the characteristics of polyomaviruses?

A

Ubiquitous, most seropositive by age 15
Disease in immunocompromised people
Consist of BKV and JCV
BKV establishes latent infection in kidney
Severe urinary tract infection by BKV after reactivation
JCV in the kidneys, B cells, monocyte lineage cells
JCV reaches CNS
JCV destroys oligodendrocytes causing demyelination

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17
Q

What are the BKV diseases?

A

Ureteral stenosis in renal transplant patients

Hemorrhagic cystitis in bone marrow transplant recipients

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18
Q

What are the JKCV diseases?

A

Progressive multifocal leukoencephalopathy (PML) associated
Incidence of PML is up due to people with AIDS and on immunosuppressive drugs
Multiple neurologic symptoms-speech, vision, coordination

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19
Q

How to diagnose polyomaviruses?

A

PCR of CSF for PML
Brain imaging
DNA analysis of urine
Biopsy

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20
Q

What are the characteristics of adenoviruses?

A

Capsid has fibers at vertices
Encodes its own DNA polymerase
Causes lyric, persistent and latent infections
Risk for younger than 14 years, crowded living like daycare, military camp,
exposure to inadequately chlorinated swimming pools
Antibody is important for prophylaxis and resolution

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21
Q

What is the epidemiology of adenovirus?

A

Spread in aerosols, fecal matter, and by close contact
Fingers spread virus to eyes
Infects mucoepithelial cells in RT, GIT, conjunctiva/cornea
Causes direct cell damage
May persist in lymphoid tissue

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22
Q

What are the adenoviruses diseases?

A

Acute febrile pharyngitis and pharyngoconjunctival fever
Follicular conjunctivitis
Swimming pool conjunctivitis-common source
Keratoconjunctivitis- among industrial workers
Acute respiratory tract disease
Gastroenteritis and diarrhea

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23
Q

What are the characteristics of acute febrile pharyngitis and pharyngoconjunctival fever?

A

Pharyngitis that is often accompanied by conjunctivitis
Pharyngitis alone in children less than 3 year mimics strep throat
Pharyngoconjunctival fever in outbreaks involves older children

24
Q

What are the characteristics of acute respiratory tract ?

A

Fever, cough, runny nose, pharyngitis and conjunctivitis
High incidence among military recruits
Live vaccine f9r serotypes 4 ne 7 for military use

25
Q

What are the characteristics of gastroenteritis and diarrhea ?

A

Major cause of acute viral gastroenteritis in infants

Enteric adenoviruses rarely cause fever or respiratory tract symptoms

26
Q

How to diagnose adenovirus?

A

Virus in throat of a patient with pharyngitis
Test should eliminate streptococcus pyogènes
Nuclear inclusions bodies produced by infection
DNA analyses
Immunological probes

27
Q

What are the characteristics of HSV-1 and 2?

A

Produce lytic, persistent, recurrent and immortalizing infections
Share DNA, protein homologue, tissue tropism and disease signs
Infections cause direct CPE
Spread cell to cell and syncytium to avoid antibodies
Stress or immune suppression leads to reactivation

28
Q

What is the epidemiology of HSV-1 and 2?

A

Transmitted via saliva, vaginal secretions or by lesion fluid
HSV-1 transmitted orally, HSV-2 sexually but not exclusively
Initial disease at the site of infection and then latency
Latency in the innervation neurons
Trigeminal ganglia for HSV-1
Sacral ganglia for HSV-2
Lesions occur at the same location
Vesicular lesions contain infectious virions

29
Q

What are the characteristics of oral herpes?

A

Can be caused by HSV-1 or 2
begin as clear vesicles that rapidly ulcerate
Distribute around or throughout the mouth
Recurrence of mucocutaneous lesions
Also called cold sores, fever blisters

30
Q

What are the characteristics of herpetic keratitis?

A

Mostly limited to one eye
Can cause recurrent disease
May lead to permanent scarring, corneal damage, blindness

31
Q

What are some other herpetic diseases?

A

Herpetic whitlow-infection of the finger mostly in nurses and physicians
Herpes gladiatorum- infection of the body common among rugby players and wrestlers

32
Q

What are the characteristics of genital herpes ?

A

Can be caused by HSV-1 or HSV-2
Anal sex can lead to HSV proctitis
Painful lesions may be accompanied by fever , malaise, myalgia

33
Q

What are the herpes encephalitis?

A

Usually caused by HSV-1 but can be caused by HSV-2
Lesions limited to one of the temporal lobes
Infections causes destruction of temporal lobe
RBCs in CSF
Patients may have seizures and focal neurologic abnormalities

34
Q

What are the HSV infections in neonates?

A

A severe (may be fatal) disease caused mostly by HSV-2
Acquired in utero or during passage of birth canal
Babies appear septic with or without vesicular lesions
No CMI-dissemination to liver, lung and the CNS
Results in death or neurologic disability even with treatment

35
Q

How to diagnose HSV-1 or 2 ?

A

Confirmation by immuno or DNA based methods
Serology useful for primary infection
Recurrent infections do not show increase in titers
Encephalitis: normal glucose, mildly increase of protein and absence of pathogens in CSF

36
Q

What are the characteristics of the varicella-zoster virus (HHV 3)?

A

Virus that causes lifelong infection
Acquired from respiratory droplets or skin contact
Produce vesiculopustular rash with crops of lesions
Pneumonia in adults or among I/C individual
Contagious from 1st day of symptom till last blister crushed
Infection leads to latency especially trigeminal ganglia
Reactivation with lesion shows dermatomal pattern (shingles)

37
Q

What are the characteristics of the chickenpox?

A

Mild childhood but mostly symptomatic disease
1/5 of childhood exanthems (rubella, roseala, fifth disease,measles)
Fever and maculopaular lesions after 14 days
Within 12 hours vesicles are pustular and begin to crust
Crops of lesions in different stages
Rashes prevalent on trunk and head and also scalp
Risk of bacterial superinfection with lesion itch
Primary lesions more severe in adults ythan children

38
Q

What are the characteristics of herpes zoster?

A

Recurrence of latent varicella acquired earlier in life
Severe pain in the area innervating the nerve before lesions
Chickenpox like lesions limited to a dermatome

39
Q

What are the characteristics of VZV in I/C patients?

A

Lack of CMI causes serious and potentially fatal disease
VZV dissemination to the lungs, brain, and liver
May occur during primary exposure or because of recurrence

40
Q

How to diagnose VZV?

A

Presence of typical rash
Serology and genome detection
Positive Tzanck, Cowdry type A intranuclear inclusions

41
Q

What are the characteristics of EBV(HHV4)?

A

Spread via close oral (kissing disease) or personal contact
Milder symptoms in children
Teenagers/adults at risk for infectious mononucleosis (IM)
Limited tissue tropism, receptor (CR2 or CD 21) on B cells
Heterophile positive IM

42
Q

What are the 3 potential outcomes for EBV?

A

Replication in B cells or permissive epithelial cells
Latent infection of memory B cells in the presence of CMI
Can stimulate and immortalize B cells

43
Q

What is the epidemiology of EBV?

A

Diseases from an overactive immune response
Lack of immune response causes lymphoproliferative disease and hairy cell leukoplakia
EBV infects B cells and causes their outgrowth
Activation of T cell responses to control B cells outgrowth
Classic lymphocytosis
Swelling in lymphoid organs
Malaise/fatigue from activation and proliferation of T cells

44
Q

What are the characteristics of the heterophile antibody positive IM?

A

Triad of classic symptoms
Lymphadenopathy,splenomegaly and exudative pharyngitis
High fever and malaise
Rarely fatal in healthy people
Fatigue due to amount energy spent in T cells activation
Complications are meningoencephalitis and Guillain-Barre syndrome

45
Q

What are the characteristics of EBV induced lymphoproliferative disease?

A

May be life threatening in T cell deficient individuals
Polyclonal leukemia
Associated with African Burkitt lymphoma
Burkitts lymphoma
Also with Hodgkin lymphoma and nasopharyngeal carcinoma

46
Q

What are the characteristics of hairy oral leukoplakia?

A

Unusual manifestation

Lesions on tongue and mouth that occurs in AIDS patients

47
Q

How to diagnose EBV?

A

Lymphocytosis (70% monocytes)
Atypical lymphocytes
Serology to viral antgens
Positive heterophile test

48
Q

What are the characteristics of cytomegalovirus (CMV,HHV 5)?

A

Spread via blood, organ transplants, saliva, breast milk, sexual routes (semen, cervical secretions)
Most prevalent viral risk for congenital defects
Majority of infections are asymptomatic

49
Q

What are the characteristics of perinatal infection?

A

Usually no symptom in healthy full term infants
Premature infants may need blood transfusion
Can have pneumonia and jaundice if CMV conataminated

50
Q

What are the characteristics of CMV infections in children and adults?

A

70-85% infected in the US by age 40
Prevalent in low socioeconomic and in crowded conditions
Probably an STI
90-100% patients at STD clinics are infected

51
Q

How to diagnose CMV?

A

In adults with IM, negative heterophile antibody test
Presence of owl’s eye cells
Serology and DNA based methods
Isolation of virus from infant urine during 1st week postpartum

52
Q

What are the characteristics of HSV-6 and HSV-7?

A

Lymphotropic and ubiquituous
45% by age 2 and 100% serpositive by adulthood
HSV-6 has 2 variants 6A and 6B
HHV-6 replicates in salivary gland and transmitted in saliva
HHV-6 primarily infects lymphocytes especially CD4 T cells
HHV-6B or HHV-7 can cause exanthem subitum (roseola)
Rapid onset of fever of few days followed by rash
Rash only lasts 24-4 hours

53
Q

What are the characteristics of HHV-8?

A

Kaposi sarcoma associated virus
Infects B cells and some endothelial cells
Transmitted sexually via semen
Polyclonal dark lesiomns in AIDS patients
Diagnosed by clinical picture and viral DNA in peripheral lymphocytes

54
Q

What are the characteristics of poxviruses?

A

Brick or ovoid shaped virus surrounded by 2 membranes
contagious human to human via droplets or skin contact
After inhalation, replicates in upper respiratory tract
Spread via lymphatic and viremia
Infects internal and dermal tissues after a second more intense viremia
Simultaneous eruption of hemorragic lesions
2 groups: variola major and minor
only one serotype facilitated vaccine ddevelopment

55
Q

What is the epidemiology of the variola?

A

Infection of reticulo and vascular endothelial and epithelial cells
5-17 days incubation period
High fever,fatigue, severe headache, backache and malaise
Vesicular rash in mouth and soon after on the body
Major feature is the appearance of lesions at the same stage
Diagnosis done by clinical picture but confirmed by culture
Infected cells contain a cytoplasmic Guarnieri inclusion body

56
Q

What are the characteristics of molluscum contagiosum virus?

A

Causes a slow developing infection
Spreads by direct contact or fomites
More often in children
Genital lesions are transmitted sexually in adults
Can infect any part of skin mostly AIDS associated disease
Self limiting infection of epithelial cells
Nodular or wart like and a tiny dimple in the center
Lesions usually not itchy or painful
Discovered mostly during a physical exam
Diagnosis: large,eosinophilic inclusions in epithelial cells

Microbiology (8 decks)

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