Herpes Flashcards
Double-stranded DNA genome
enveloped
Genome = 125,000 -236,000 base pairs
1. Encode a large array of enzymes involved ina. nucleic acid metabolism (thymidine kinase, thymidylate synthetase, dUTPase, ribnucleotide reductase)b. DNA synthesis (DNA polymerase, helicase, primase)c. protein processing (protein kinases)
2. Synthesis of viral DNAs and capsid assembly occur in the nucleus, while final processing of virions occurs in the cytoplasm
3. Production of virus results in destruction of the infected cell
4. Able to exist in a latent state in their natural hosts while retaining the capacity to replicate and cause disease upon reactivation
Human Herpesviruses (Chapters 41 and 42)
What are the 4 significant biological properties shared by the herpes viruses?
- Encode a large array of enzymes involved ina. nucleic acid metabolism (thymidine kinase, )
b. DNA synthesis (DNA polymerase)
c. protein processing (protein kinases) - Synthesis of viral DNAs and capsid assembly occur in the nucleus, while final processing of virions occurs in the cytoplasm
- Production of virus results in destruction of the infected cell
- Able to exist in a latent state in their natural hosts while retaining the capacity to replicate and cause disease upon reactivation
_____ herpesvirus:
HSV-1 (HHV-1) fever blisters
HSV-2 (HHV-2) sexually transmitted genital lesions
VZV(HHV-3) chicken pox and shingles
Alpha herpesviruses
_____ herpesvirus:
CMV
HHV-6 roseola
HHV-7 Roseola
Beta herpesviruses
_____ herpesvirus:
EBV (HHV-4) infectious mononucleosis
Kaposi’s sarcoma-associated herpesvirus
Gamma herpesviruses
______ viruses are fragile (enveloped)susceptible to heat, detergent, drying
Herpes
Generally require direct inoculation
mucous membranes more susceptible than skinCMV and EBV can be transmitted through infected leukocytesVZV is mostly transmitted by aerosols
Herpes
____:
Cascade of gene expression
Attach to and infect adjacent cells upon release
Budding directly onto and into adjacent cells
Therefore get a local spread of virus (predominantly)
Syncytia can form
Herpesvirus lytic cycle
Get changes in nuclear structure -chromatin shifted to margins of nucleus
-Cowdry type A acidophilic intranuclear inclusion bodies
herpes virus
Stained cells infected with a herpes virus show _____ formation (multinucleated cells)(= Tzanck cells from Tzanck smear (scraping from the base of the lesion) and _______ bodies (darkly staining nuclear region).
syncytia formation; intranuclear inclusion
Anti-herpesvirus antibodies play _____ role in recovery from primary disease and on recurrent disease
minor
anti-herpes virus antibodies can help prevent ______
VZV vaccine is effective
primary disease
Cell-mediated immune mechanisms play the _____ role in recovery
major
MHC class I and II proteins displaying viral antigens on surface of infected cell activate T lymphocytes directly kill the infected cell or secrete cytokines and chemokines to attract macrophages, etc. Cell-mediated immune response varies with age neonates: problems with HSVs; elderly: problems with VZV
CMI herpes virus immune response
HSV-1, HSV-2, and VZV envelope glycoproteins bind ____domain of antibodies and complement components, blocking their ability to promote an antiviral response.
Fc domain
____ proteins reduce type I interferon production and its downstream signaling pathway
HSV proteins
_____ proteins can prevent MHC class I and II proteins from being expressed on the surface of infected cells
HSV proteins
____ results in no expression of viral proteins and therefore no peptides for MHC proteins to display
Latency
_____: disease facial or genital herpes, stomatitis, or keratitisl ocalizied
Acute herpes
Exposure of skin, mucosa, or cornea to secretions containing virus
Replication of virus in epithelial cells, causing vesicular mucocutaneous lesions, stomatitis, or keratitis
Spread to peripheral sensory or autonomic nerve endings and ganglia
Acute herpes
____: acquired very early in life (e.g. kissing)2/3 of adults are Ab+
HSV-1
____: mostly transmitted by genital contact uncommon before adolescence1/5 of adults are Ab+
HSV-2
Are HSV-1 or 2 infections symptomatic or asymptomatic?
Asymptomatic
Healing of lesions and establishment of latent infections in neurons
- Recovery
Maintenance of latent infections in neurons
- Latency
______: cold sores, fever blisters, keratitis, or genital lesions localized
-Reactivation of latent virus and distal spreadRecurrent lesions caused by virus replication in epithelial cells
- Recurrent disease
\_\_\_\_\_\_ of various herpesviruses can be induced by: Local trauma (surgery or nerve pressure) Mental tension Fatigue Menstruation Exposure to bright light Aging effects
reactivation
Ocular herpes is which HSV?
1
Oral herpes is mainly which HSV?
1
Genital herpes is mainly HSV?
2
____ is an infection of the eye related to herpes and can lead to scarring/blindness
Herpes keratitis
______; vesicles on oral mucosa, the tongue, and gingivae confused with acute necrotizing ulcerative gingivitis (ANUG) when gingivae inflamed
Primary infection by HSV-1 or HSV-2
_____: -reactivation of latent HSV-1 or HSV-2
Herpes labialis (cold sore)
_____ causes chicken pox and shingles
VZV
Aerosol transmission
Local viral replication in respiratory tract
Virus progresses to phagocytic cells via the bloodstream and lymphatic system
Secondary viremia spreads the virus throughout the body, including the skin
occurs 11-13 days post infection
skin lesions appear over the entire body
systemic spread is different from herpes simplex viruses
Virus spreads cell-to-cell like HSVs except epithelial cells of lung keratinocytes and skins lesions, which can release virus
VZV
_____ replication is similar to HSVs but slower [smallest genome of HHVs (~125,000 bp)]
also establishes latent infection of neurons
dorsal root ganglia or cranial nerve ganglia
VZV
_____ reactivated in older adults with impaired cell-mediated immunity
virus is released along the entire neural pathway to infect the skin
causes a vesicular rash along the entire dermatome = herpes zoster or shingles
postherpetic neuralgia in 30% of older patients
pain for months to years after zoster
VZV
______ is area of skin innervated by fibers from a single dorsal root spinal nerve
Dermatome
Anti-VZV antibodies play ____ role in recovery from primary disease and on recurrent disease
minor
Cell-mediated immune mechanisms play the _____ role in recovery as for HSVs
major
)infects B lymphocytes and epithelial cells
Epstein-Barr virus (EBV; HHV-4
infects a wide variety of cells
Cytomegalovirus (CMV; HHV-5)
____ and _____ replication within host cells is very similar to general description of herpesvirus replication given previously
EBV and CMV
Establishment of _____ persistent/chronic infection
CMV
Establishment of _____ latent infection
latent infection in memory B cells
virus proteins produced during latency promote B cell proliferation
EBV
\_\_\_\_and \_\_\_\_\_ infections are very common 95% of adults in developing world 50-60% of adults in United States usually asymptomatic when acquired early
CMV and EBV
breast milk not a important route of virus spread
Symptomatic infections when acquired after childhood: infectious mononucleosis
EBV
most common viral infection of the fetus in humans
leads to severe disease and permanent neurological damage,
including hearing loss and learning disabilities
Congenital CMV
_______ is seen in: Hodgkin disease, African Burkitt lymphoma, and nasopharyngeal carcinoma
EBV:
large inclusions in tissue specimens (“owl eye”inclusions)
CMV
- PCR
- heterophile antibody or “monospot” test
- infection induces production of large number of antibodies that recognize RBC antigens of other species (“heterophile antibodies”)
- Monospot test: agglutination of horse RBCs by heterophile antibody in patient’s serum
EBV
_____ virus: congenital infection and mononucleosis
CMV
____ virus:mononucleosis
EBV
______: roseola
HV-6 and 7
trigeminal nerve affected in 15% of cases
Ophthalmic > maxillary > mandibular divisions involved (lesions)
oral pain often precedes rash and mimics toothache pain
most common intraoral sites affected:
anterior half of tongue
soft palate
cheek
Shingles (VZV)
-infectious mononucleosis
painful sore throat at onset of infection
rash may be present at junction of hard and soft palates (fine petechial hemorrhages)
White pseudomembrane may develop on tonsils and other parts of oral mucosa
Epstein-Barr virus (EBV)
_______ and _____ are present in majority of advanced periodontal lesions
Epstein-Barr virus(EBV) and cytomegalovirus (CMV)
Possible roles for herpesviruses in ________:
- Viruses may cause direct cytopathic effects
- Gingival viruses may promote bacterial attachment/colonization
- CMV and EBV can infect monocytes, macrophages, and lymphocytes in lesions and impair cell function.
- Viruses induce a proinflammatory response that can result in tissue destruction.
- Viruses can suppress host defenses locally and systemically
periodontal disease
