Viral Skin Infections (Virus) Flashcards
Vesicular or Pustural Rash Diseases - major viral causes
HHV-1* (Neuro, HRM) HHV-2* (Neuro, HRM) HHV-3 Coxsackieviruses A and B Smallpox Orf virus* (in handout)
Maculopapular Rash Diseases - major viral causes
Measles* (Neuro, IHO) Rubella Parvovirus B19 Roseoloviruses (HHV-6 and HHV-7) HHV-4* (in IHO) ECHO virus* (in handout) West Nile Virus* (in handout)
Wartlike eruptions - major viral causes
HPV
Molluscum contagiosum
Steps of Viral Infection inside organism
Replication at site of entry Primary viremia Replication Secondary viremia Replication Transmission to other hosts *See picture*
Herpesvirus infections last a life time in a state called ____
latency
Herpesvirus do/do no integrate into host genome
Do not
They make proteins that mediate genome persistence in host cells by binding to the viral genome and ensuring that as the host cell divides that the viral genome is copied.
Herpesvirus can/cannot reactivate
Can - more infectious
virus - dsDNA (group I) - linear genome - icosahedral nucleocapsid - enveloped
herpesvirus family
herpesvirus subfamilies
alpha: simplexvirus (1 and 2) Varicellovirus (VZV) beta: cytomegalovirus (HCMV, HHV-6/7) gamma: Lymphocryptovirus (EBV) Kaposisarcoma-associated herpesvirus
herpesvirus tree
virus - dsDNA (group I) - linear genome - icosahedral nucleocapsid - enveloped
Herpes simplex 1
alpha - Human herpesvirus 1 (HHV-1)
Above waist - gingivostomatitis, herpes labialis, etc.
Herpes simplex 2
alpha - Human herpesvirus 2 (HHV2)
Below wait - genital herpes or neonatal herpes
Varicella-Zoster virus
alpha - HHV-3
Chickenpox or shingles
Human cytomegalovirus
beta - HHV 5
Congenital CMV infection, systemic, mono-like
Roseoloviruses
beta - HHV 6(a,b)/7 - exanthem subitum (6th disease), encephalitis in IC
Epstein-Barr Virus
gamma- HHV-4 - mononucleosis, lymphoid-organ related cancers
Kaposi Sarcoma-Associated Herpesvirus
gamma - HHV8 - Kaposi sarcoma
first disease
measles
second disease
strep pyogenes (scarlet fever)
third disease
rubella
fourth disease
staph aureus (SSSS)
fifth disease
parvovirus B19 (slapped cheek)
sixth disease
HH6/7 - roseola
Virus lifecycle
attachment - penetration/adsorption - synthesis - assembly - release
HHV1 and HHV2 cause
mucosal lesions, encephalitis
HHV1 and HHV2 transmission
saliva, vaginal secretions, lesion fluid
1 - mainly oral
2 - mainly sexual
HHV1 and HHV2 vaccines
no vaccine
HHV1 and HHV2 drugs
acyclovir etc.
HHV1 and HHV2 disease mechanism
virus spreads cell to cell, not neutralized by antibody
cell-mediated immunopathology –> damage and sxs
cell mediated immunity required for resolution of infection
virus establishes latency in neurons
reactivated by stress or immune suppression
VZV diseases
chickenpox, shingles
VZV transmission
respiratory droplets or contact
VZV risk factors
contact, IC
disease severity worsens as get older
VZV vaccines
Live vaccine for both (separate)
VZV drugs
antiviral drugs - acyclovir, foscarnet
VZV disease mechanisms
infects epithelial cells and fibroblasts, spread by viremia to skin, causes lesions (CP)
CM-immunopathology contributes to sxs
CM-immunity required for resolution of infection
Latent infection in neurons
Reactivation by immune suppression (from DRG) Reactivation leads to zoster or shingles, formation of lesions over entire dermatome
VZV incubation period
15 days, contagious period for 10, then latency in DRG
Poxvirus
virus - dsDNA (group 1) - linear genome - complex nucleocapsid - enveloped - poxviridae
Poxvirus subfamilies
Molluscipoxvirus (Molluscum contagiosum)
Orthpoxvirus (smallpox)
Parapoxvirus (Orf virus)
Poxvirus disease mechanisms
infects respiratory tract, spreads through lymphatics and blood
MC and zoonoses transmitted by contact
Sequential infection of multiple organs
cell-mediated and humoral immunity important to resolve
Picornavirus (enterovirus) disease mechanism
Enter oropharyngeal or intestinal mucosa secretory IgA can prevent infections spread by viremia to target tissues serum Ab blocks spread virus shed in feces high asymptomatic infection rate
virus - dsDNA (group 1) - linear genome - complex nucleocapsid - enveloped -
poxvirus
virus - ssRNA (+) Group IV - nonsegmented - icosahedral nucleocapsid - picornavirdidae
enterovirus
enterovirus
virus - ssRNA (+) Group IV - nonsegmented - icosahedral nucelocapsid - picornaviridae
enterovirus subfamilies
poliovirus coxsackievirus A & B --> HFM Echovirus --> various rashes Rhinovirus Enterovirus
Hand Foot Mouth caused by
Coxsackie A virus predominantly
Measles virus aka
Rubeola
virus - ssRNA (-) Group V - nonsegmented - helical nucleocapsid - enveloped - paramyxoviridae - morbillivirus
measles virus (rubeola)
Rubeola tree
virus - ssRNA (-) Group V - nonsegmented - helical nucleocapsid - enveloped - paramyxoviridae - morbillivirus - measles virus
measles disease mechanism
infects epithelial cells of respiratory tract, spreads to lymphocytes and by viremia
replicated in conjunctivae, respiratory tract, urinary tract, lymphatic system, blood vessels and CNS
T-cell response to virus-infected capillary endothelial cell –> rash
cell mediated immunity required to control infection
complications d/t immunopathogenesis or viral mutants
infects epithelial cells of respiratory tract, spreads to lymphocytes and by viremia
replicated in conjunctivae, respiratory tract, urinary tract, lymphatic system, blood vessels and CNS
T-cell response to virus-infected capillary endothelial cell –> rash
cell mediated immunity required to control infection
complications d/t immunopathogenesis or viral mutants
measles disease mechanisms
infects respiratory tract, spreads through lymphatics and blood
MC and zoonoses transmitted by contact
Sequential infection of multiple organs
cell-mediated and humoral immunity important to resolve
poxvirus disease mechanisms
Enter oropharyngeal or intestinal mucosa secretory IgA can prevent infections spread by viremia to target tissues serum Ab blocks spread virus shed in feces high asymptomatic infection rate
picornavirus disease mechanisms
virus spreads cell to cell, not neutralized by antibody
cell-mediated immunopathology –> damage and sxs
cell mediated immunity required for resolution of infection
virus establishes latency in neurons
reactivated by stress or immune suppression
HHV 1 and 2 disease mechanisms
infects epithelial cells and fibroblasts, spread by viremia to skin, causes lesions
CM-immunopathology contributes to sxs
CM-immunity required for resolution of infection
Latent infection in neurons
Reactivation by immune suppression (from DRG) Reactivation leads to zoster or shingles, formation of lesions over entire dermatome
VZV disease mechanisms
rubella virus aka
German measles
virus - ssRNA (+) Group IV - nonsegmented - icosahedral nucleocapsid - enveloped - togaviridae - rubivirus -
Rubella virus
rubella virus tree
virus - ssRNA (+) Group IV - nonsegmented - icosahedral nucleocapsid - enveloped - togaviridae - rubivirus -
erythema infectiosum
fifth disease
mild by highly contagious disease - slapped-cheek appearance
fifth disease causative agent
parvovirus B19
Parvovirus B19
Virus - ssDNA group II - linear genome - icosahedral nucleocapsid - nonenveloped - parvoviridae - erythrovirus (parvovirus B19)
Virus - ssDNA group II - linear genome - icosahedral nucleocapsid - nonenveloped -
parvoviridae - erythrovirus (parvovirus B19)
Parvovirus complications
aplastic crisis, acute polyarthritis, abortion
Sixth disease “Roseola”
young children, babies
high fever up to 105 then maculopapular rash (or not)
First on chest and trunk
by time rash, disease almost over
Roseola causative agent
HHV6/7 - can remain latent
IF HHV6/7 reactivate from latency in adulthood
mono-like, hepatitis-like
vaccine or drugs for roseola?
None
Virus - dsDNA group 1 - circular genome - icosahedral nucleocapsid - nonenveloped - papoviridae
papillomavirus