Viral infections in vesicles, bullae, pustules

Question 1

Varicella zoster

Answer 1

Viral infections in vesicles, bullae, pustules
• dsDNA
• enveloped
• replicates in nucleus
• *typical intranuclear inclusions
• human reservoir
• **infects epithelial cells, fibroblasts, T cells, neurons
• occurs in presence neutralizing antibodies to VZV
• *immune evasion→ VZV downregulates MHC I, MHC II antigen expression
• can infect susceptible → chickenpox
DISEASE
• chickenpox= varicella= primary infection w/ VZV
• zoster= shingles= localized recurrence latent VZV
- *latent in trigeminal and dorsal root ganglia
- *unilateral
- trunk, head, neck most common
-eruption may cause disabling pain
• *lesions usually restricted to 1 or 2 dermatomes, not widespread
• *pain usually precedes lesions; may be accompanied by fever, malaise

Question 2

genital herpes

Answer 2

Viral infections in vesicles, bullae, pustules
• *DS DNA
• replicates in *nucleus
• enveloped, icosahedral
• multiply in *mucosal epithelial cells
• recurrent, *lifelong
• *HSV-2 (~90% genital herpes), HSV-1
• transmission: *respiratory droplets, direct contact infected saliva
• *primary infect. usually asymptomatic
• fever, sore throat, vesicular and ulcerative lesions, gingivostomatitis, malaise
• HSV-1 latent in *trigeminal ganglia
• recurrences manifested as ‘cold sores’=‘fever blisters’= *PRODROME before blisters occur

DIAGNOSIS
– *Tzanck test of material from lesions

Question 3

Coxsackievirus

Answer 3

Viral infections in vesicles, bullae, pustules
Picornaviridae
• icosahedral
• *(+)ssRNA, linear, nonsegmented
• replicates in *cytoplasm
• *naked
• *resistant
• replicates in *submucosal lymph tissue and disseminates via reticuloendothelial system
• further *dissemination to target organs occurs following a *secondary viremia
• *transmission fecal-oral, direct contact mucus, saliva, feces, fomites
• wide range disease
• Coxsackie B is associated with *viral heart disease
DISEASE
Hand foot mouth disease
• coxsackieviruses *A16
• usually *infants
• vesicular lesions, mouth usually first
• low-grade fever, malaise, abdominal pain, resp. symptoms
• *very contagious

Question 4

Poxviridae

Answer 4

Viral infections in vesicles, bullae, pustules
• *linear dsDNA
• *largest viruses
• *brick- to ovoid-shaped
• *lipoprotein envelope
• stable in environment
• packages all needed enzymes and factors for viral replication
DISEASE
- cause smallpox & 
- *variola virus=smallpox
RASH of smallpox vs. rash of chickenpox
• general distribution fully developed rash of *smallpox is *centrifugal
   – *more lesions on arms and legs than on trunk
   – *palms and soles commonly affected
• rash of chickenpox is *centripetal
   – *more lesions on trunk
   – *hands and soles few or no lesions

Question 5

Vaccinia virus

Answer 5

Viral infections in vesicles, bullae, pustules
• vaccinia has broad host range
• **smallpox vaccine= live, attenuated vaccinia virus
• vaccine complications:
– *vaccinia rash entire body
• self-limited in immunocompetent
• often fatal in immunocompromised
– *postvaccinal encephalitis
• often fatal
– *fetal vaccinia
• rare, usually results in stillbirth