Micro: Ryan/Whitt Flashcards
parvovirus B19
FIFTH DISEASE
non-enveloped, ssDNA
S PHASE replication: RBC PRECURSORS
transmission: respiratory, percutaneous through blood, mother to fetus: vertical transmission
human herpes virus 6 & 7
ROSEOLA
enveloped, large dsDNA
complications due to long-term latent infection if become immunosuppression (STEM CELL TRANSPLANT recipients): brain, lung, heart, kidneys, GI; COGNITIVE DYSFUNCTION, permanent disability and death
paramyxovirus
MEASLES, MUMPS
enveloped, large -ssRNA
togavirus
RUBELLA
enveloped, +ssRNA
Sx: mild, MORBILIFOM rash (maculopapular) on FACE that spreads to rest of body, low fever, conjunctivitis, sore throat, LAD
transmission: aerosol
isolate: stool, nasopharynx
viral shedding: continues after rash disappears
CONGENITAL BIRTH DEFECTS: 1st and 2nd trimester: retardation, motor disability, hearing loss, congenital heart disease, cataracts, BLUEBERRY MUFFIN rash
picronovirus (enteroviruses)
COXSACKIE A, ECHO, ENTEROVIRUSES
non-enveloped, +ssRNA
differentiate from rhinovirus: acid stability, less stringent growth requirement (human and primate cell lines, grows well at 37 C)
HUMANS only known reservoir
oral-fecal route, fomites
lymphoid replication: URT, tonsils, lymph nodes, Peyer’s patches, small intestine; followed by viremia and infects spinal cord, brain, meninges, myocardium, skin
isolated: throat culture
Coxsackie A
HAND, FOOT, MOUTH DISEASE
HERPANGINA
Sx: asymptomatic is common
MENINGITIS
ECHO
transient, non-descript rash
MENINGITIS
Enteroviruses
asymptomatic, self limiting (Polio is exception)
seasonal: summer and fall
measles
paromyxovirus: Morbilivirus genus
MV receptors: CD46, SLAM, NECTIN-4
H and F proteins (persistent CNS infection)
intracellular INCLUSION bodies
requires population greater than 100,000: under-vaccination, reservoir of susceptible individuals
respiratory route: extremely contagious
Sx: 10-14 days latent, HIGH FEVER, generalized RASH (T CELLS attack measles virus-infected vascular ENDOTHELIAL cells), COUGH, CORYZA, CONJUNCTIVITIS (PHOTOPHOBIA), MACULOPAPULAR RASH (cell mediated immune response and virus clearance); KOPLIK spots
mortality: bacterial pneumonia
MUST REPORT
LIFE-LONG immunity
Koplik spots
ONLY in measles
small abruption with blue-white centers in mouth
right before rash
MIBE
measles inclusion body encephalitis
result from persistent MV infection in brain
SSPE
subacute sclerosing panencephalitis
result from persistent infection in brain (years)
ADEM
acute disseminated encephalomyelitis
autoimmune demyelinating disease
against MYELIN BASIC PROTEIN
convulsions, deaf, retardation
PIE
postinfectious encephalomyelitis
autoimmune demyelinating disease
against MYELIN BASIC PROTEIN
convulsions, deaf, retardation
measles virus eradication
immunization: one serotype, clinical identifiable, no animal reservoir
requires HERD IMMUNITY
1963-67 vaccine not effective
MMR vaccine
mumps, measles, rubella
live, attenuated: life long immunity
SC
MMR at 12-15 months, 4-6 years 2nd dose; do not start before 6 months (mom Ab make vaccination incomplete)
vaccine effectiveness: ANTIGENICALLY STABLE MONOTYPIC VIRUSES
post exposure: MMR vaccine within 72 hrs of exposure or Ig within 6 days
only HUMANS have these viruses
CI: allergy to eggs, pregnancy, immunodeficient
MMRV (varicella): more AE
complication of measles
IMMUNE SUPPRESSION for a month after onset of rash (type IV hypersensitivity suppressed: TB), production of Ab and cell-mediated antigens suppressed (monocyte infection)
neuro: ADEM, PIE, MIBE, SSPE
Coxsackie B
pleurodynia, myocarditis, pericarditis
Hand, Foot, and Mouth disease
coxsackievirus A16, A6, enterovirus71 HERPANGIA, fever, , headache, sore throat, abdominal pain, vesicular lesions on hands and/or feet isolate: lesions and feces highly contagious Tx: symptomatic
herpangia
round erosions on tongue and soft palate
roseola
HHV-6/7
6 months - 4 yrs
high fever, non-itchy rash that disappears, loose stools
mumps
NO RASH
URT to lymph nodes
PAROTID swelling
complication (CNS): MENINGITIS, DEAF (cochlea infection), post-pubertal men TESTES swell: INFERTILITY (not as child)
virus shed 6 days before onset of disease
fifth disease (erythema infectiosum)
PARVO B19
children: erythematous rash on chest and arms LACEY RASH, SLAPPED CHEEK (very pink cheeks)
adults: less rash, polyarthritis, flu-like
biphasic: lytic infectious phase (flu-like), then couple weeks non-infectious immunologic phase (IgG neutralizes virus, rash)
CYTOKINE: flu-like
CELL MEDIATED: rash
complication: transient APLASTIC CRISIS (sickle cell), chronic ANEMIA (immunocompromised); miscarriage, fetal anemia, hydrops fetalis (vertical transmission)
huma papilloma virus (HPV)
small circular dsDNA, non-enveloped, icosahedral
benign tumor: full length, circular, extrachromosomal
malignant: integrate into chromosome, partial genome, lose E2 (activates E6/7)
doesn’t encode own DNA pol
Sx: warts, cervical/head/neck CA (non-permissive cells), infantile laryngeal papillomas, epidermodysplasia verruciformis
Dx: clinical, genotyping on inconclusive Pap smears in women over 30
Tx: warts spontaneously regress, Sx, cryoSx, corrosives; imiquimod cream
recurrence common
permissive cells
HPV
lytic replication
non-permissive cells
HPV
genome is replicated but no virus particles are produced
late structural genes not expressed: no capsid made
TRANSFORMATION
wart morphogenesis
HPV
1. virus infection through break in skin
2. migrates to progenitor skin cells that are nonpermissive
cells migrate to surface and become keratinocytes and can now replicate episomally and produce late genes and virus packaging
3. can infect another area where break in skin is: mounds/satellite warts
E2
HPV malignancy
suppresses E6 and E7
E6
HPV malignancy
degrades p53
E7
HPV malignancy
inactivates Rb protein
cell cycle control is lost
Gardasil
vaccine
3 IM doses: age 11-26 years
HPV 6, 11, 16, 18 virus made in yeast
L1 capsid protein that assembles into pseudocapsids
herpesvirus
linear, dsDNA, enveloped, icosahedral, glycoproteins (on infected cells and virus allowing fusion of infected cells with non-infected cells)
replicated and assembled in nucleus
epithelial cells, neuronal cells
lytic, latent (establishment, maintenance, reactivation lapse in cell mediated immunity but localized due to high Ab)
HSV-1, HSV-2, VZV
HSV-1
SKIN: herpetic gingivostomatitis, herpes labialis, herpes gladiatorum (wrestler’s: saliva in scrape), herpetic whitlow (ungloved dentist)
OCULAR (keratitis, conjunctivitis, blepharitis), ENCEPHALITIS (neonate, immunocompromised)
latent: trigeminal
Dx: PCR, TZANCK SMEAR
HSV-2
urogenital, meningitis (neonates, immunocompromised)
latent: sacral, lumbar
Dx: PCR, TZANCK SMEAR
varicella-zoster virus (VZV)
primary infection: chicken pox (spread by aerosol), severe in adults (pneumonia)
need secondary viremia for rash
reactivated: PAIN, rash along thoracic dermatome or forehead, postherpetic neuralgia (pain after rash is gone)
latent: dorsal root
Dx: clinical, TZANCK SMEAR
vaccine: children, older adults
lytic cycle of herpesvirus
- bind heparin sulfate on glycoproteins and fuse at PM
- moves to nucleus
- immediate early transcription: transcription factors (has own DNA pol)
early transcription: replication (uses host genome)
late transcription: structural - translation in cytoplasm
- reintroduced into nucleus and packaged into capsid
- bud into cytoplasm, release from ER to golgi to acquire envelope, exocytosis
LAT
HSV, not VZV
latency associated transcript
produces microRNAs: repress viral gene expression, prevent apoptosis, impair CD8 T cell function
allows virus to evade immune system, prevent lytic replication and apoptosis of infected neuron
Tzanck smear
HSV
giant multinucleated cells
poxviridae
large, complex, enveloped, linear sDNA
variola, vaccinia, cowpox, monkeypox
replicate in CYTOPLASM: produce own RNA/DNA pol and most proteins
variola
SMALLPOX
minor and major form (more fatal)
Sx: rash
transmission: inhale, lesions from infected
secondary viremia: see rash
death due to toxic effects on vascular endothelium
vaccinia
SMALLPOX vaccine
Hx: variolation, cowpox
LIVE vaccine to eradicate variola
localized lesion that heals in 2 weeks, wanes after 3 yrs, gone after 20 yrs
complications (can Tx some with cidofovir): severe rxn, life treating rxn, death due to encephalitis or shock or myocarditis/MI
effective: humans only reservoir, no healthy carriers, no sub-clinical infection, vaccine available
don’t get vaccine if: pregnant, breast feeding, immunodeficient, eczema, atopic dermatitis, under 18 unless emergency, heart disease
monkeypox
deadly to humans
molluscum contagiosum
poxvirus
child: lesions on face, trunk, lesions; spread through skin
adult: lesions on lower abdomen; STD
Dx: clinical, confirmed by cytoplasmic INCLUSIONS in keratinocytes
lesions disappear in 2-12 months
drug rashes
most common: morbilliform
delayed (type IV) hypersensitivity: T cells
less common: urticaria, angioedema, anaphylaxis, vasculitis, photoallergic
life threatening rash: SJS, exfoliative dermatitis, DRESS (drug run with eosinophilia and systemic symptoms)
rare: bollous diseases, AGE (acute generalized pustular eruption), lupus, pseudo lymphoma, lichenoid
HLA genetic predisposition in some severe rxns
leprosy (Hansen’s disease)
MYCOBACTERIUM LEPRAE: intracellular in macrophages and Schwann cells
INDIA, BRAZIL
chronic, granulomatous
peripheral nerves, superficial tissues (esp. nasal mucosa)
transmission: nasal secretions
only in humans and armadillos
low infectivity: req. prolonged close contact with infected
incubation: 2-7 yrs
depends on T cell mediated immunity: lepromatous cases lack TH1
can’t culture
tuberculoid leprosy
single skin lesions on face, limbs, butt lesions can be anesthetic (face ones usually not) low number of organism not contagious heal spontaneously prognosis: good Tx 1 year: multidrug: sulfone, rifampin
lepromatous leprosy
edema, rhinitis
extensive lesions: face, limbs, butt
severe: nasal perforation, collapse of nose, loss of fingers, atrophy of testes
ear lobe scrapings: recover acid fast bacilli
lack TH1, spread through reticuloendothelial system
Tx 2 years: multidrug: solfone, rifampin, clofazimine
