DNA Viruses Flashcards
Adenovirus
Important cause of chronic pulmonary disease in infants and young children
Necrotizing bronchitis, bronchiolitis
Mononuclear inflammatory infiltrate
Smudge cells & cowdry type A inclusions
Parvovirus B19
ssDNA
Benign self-limited febrile illness in children- Erythema infectiosum ***FIFTH DISEASE- mild exanthematous illness, accompanied by asymptomatic interruption in erythropoiesis (can lead to death in fetal infections)
Spread via respiratory route, replicated within erythroid precursors, gains entry into these cells via P erythrocyte ag and produces cytopathic effects within these cells.
*In persons with chronic hemolytic anemia, a transient aplastic crisis can occur.
Smallpox
Variola virus- highly contagious exanthematous infection
Droplets, aerosol of infected saliva
Virus is highly stable and remains infective for long periods of time outside of the host
Skin vesicles show reticular degeneration and scarce areas of ballooning degeneration,
travels to lymph nodes, where replication occurs and results in viremia
Characteristic rash, most prominent on the face
lesions quickly progress from macules to papules then to pustular vesicles
Monkeypox
rare viral disease- Poxviridae- only remaining potentially fatal infection of humans caused by this family
Similar to smallpox but milder
Papular rash occurs on the face and other parts of the body, ultimately crusts and falls off.
Infection can be from the biteof an infected host or contact with its body fluids
Herpes viruses
Herpesviridae-
ENVELOPED
Many produce type A nuclear inclusions (antigenic determinant)
**These viruses are distinguished for their capacity to remain latent for long periods of time
Varicella zoster virus
Chickenpox
1st exposure- acute systemic illness characterized by generalized vesicular skin eruption
Spread via respiratory route or contact with secretions from skin lesions
Highly contagious
Initially infects cells of the respiratory tract or conjunctival epithelium. Many organs are infected during the viremic stage. Virus spreads from the capillary endothelium to the epidermis, where its replication destroys the basal cells.
Vesicles are filled with neutrophils
Varicella zoster virus
Shingles
2nd exposure- reactivation of latent infection
Full virus replication occurs in ganglion cells and the agent travels down the sensory nerve from a single dermatome
Herpes Simplex Virus-1
Transmitted in oral secretions
Infection often occurs in childhood
Infects epithelial cells, producing progeny and destroying basal cells in the squamous epithelium
Cell necrosis also elicits an inflammatory response, neutrophils and lymphocytes
Primary infection resolves when humoral and cell-mediated immunity develop
**Herpes encephlaitis-latent in trigeminal ganglion, reactivated and travels retrograde to the brain
**Herpes hepatisis- occurs in immunocompromised
Herpes Simplex Virus-2
Transmitted in genital secretions
*Neonatal herpes- serious complication
Cellular alterations for type 1 &2: nuclear homogenization, cowdry type A intranuclear inclusions, multinucleated giant cells
Epstein Barr Virus
Infectious mononucleosis- pharyngitis, lymphadenopathy and increased circulating lymphocytes.
Contact with infected oral secretions
EBV remains for life
Infects nasopharyngeal cells and then B lymphocytes (enlarged germinal centers), which carry the virus throughout the body, producing a generalized infection of lymphoid tissue
EBV is a polyclonal acivator of B cells. Activated B cells stimulated Tcells(**Atypical lymphocytes)
Splenomegaly- hyperplasia of red pulp, liver is also involved
**Heterophile ab (Paul-Bunnell ab)
**Burkitts lymphoma & nasopharyngeal carcinoma
Cytomegalovirus (CMV)
Congenital and oppotunistic pathogen that usually produces asumptomatic infection
Spread via contact with infected secretions and bodily fluids
May remain latent for life
Crosses placenta, invades fetal cells, widespread necrosis and inflammation, involving the brain, inner ears,eyes, liver and bone marrow
Lesions of fetal CMV show cellular necrosis, characteristic cytopathic effect, consisting of marked cellular and nuclear enlargement.
Human Papillomavirus (HPV)
Proliferative lesions of squamous epithelium
dsDNA
Direct person to person contact
Virus enters the nuclei of basal cells, where it proliferates
Warts
