Term
| Characteristics of reoviruses |
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Definition
- aka rotavirus
- dsRNA viruses
- two major human infections
- rotavirus infection (infantile gastroenteritis)
- colorado tick fever (self limited, febrile illness)
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Term
| structure/genetics of rotavirus |
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Definition
- dsRNA non enveloped
- looks like a hubbed wheel (rota = wheel)
- 11 discrete segments that can reassort and each encodes a protein
- large enteric virus
- outer capsid (VP4 and VP7)
- inner capsid (VP6)
- 7 Ag groups (A, B, C in humans with A being the most common)
- B,C not usually seen in North America
- viruse encodes enterotoxin
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Term
| pathogenesis of rotavirus |
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Definition
- fecal oral transmission
- first infection btw 3-24 mnths
- prior to 3 months maternal Ab or factors in milk are protective
- life cycle
- virus binds to enterocyte receptor (receptor with higher density in younger children)
- replicates in intestinal epithelial cells
- viron must become activated in cell cytoplasm by protein cleavage of capside proteins
- uncleaved virions do not initiate replication
- activated virions replicate and assemble in cytoplasmic inclusions
- complete virons bud into ER
- envelope is lost after cell release (lysis)
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Term
| Describe immunity and potential for reinfection of rotaviruses |
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Definition
- type specific immunity
- re-infections can occur but are usually asymptomatic
- G1 type VP7 accounts for most types or rotovirus
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Term
| epidemiology of rotavirus |
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Definition
- most common cause of severe diarrhea in young children
- first infection btw 3-24 months
- cause 20% of all diarrheal deaths in children under 5
- oubreaks in child care centers
- nosocomial infections in children's hospitals
- annual peak of infection in winter
- peak season (60% of all kids admitted)
- northeast wave- late summer, see cases in southwest and as months proceed by winter, it moves up to DC and New England and Canada
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Term
| clinical manifestations of rotavirus |
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Definition
- rotavirus diarrhea associated with high fever, vomitting, and resp. tract symptoms
- more likely result in severe dehydration
- more than 20 diarrhea stools or vomitting episodes in 24 hrs
- some children with fever and vomitting without diarrhea
- most have transient rise in hepatic enzymes
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Term
| complications and fatalities of rotavirus |
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Definition
- cause- dehydration, electrolyte imbalance, and acidosis
- risk factor: malnutrition
- in immunocompromised hosts (ex: AIDS, DiGeorge's) demonstrates virus in liver and kidney
- possible cause of pneumonia
- intussusception
- SIDS
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Term
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Definition
- dx
- commercial assay for group A specific Ag detection
- stool EM
- electropherotyping
- tx
- no antivirals
- support for dehydration
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Term
| second generation rotaviruses vaccine |
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Definition
- Rotateq
- pentavalent
- for human VP7 gene (G1-4)
- first dose 6-12 weeks subsequent doses at 4-10 week intervals
- rotarix
- oral two dose live vaccine
- single human strain G1
- introduced in latin america
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Term
| colorado tick fever virus (epidemiology, clinical manifestations) |
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Definition
- zoonosis of rodents
- causes viremia, infects immature RBC's
- acute disease
- headachge
- fever
- myalgia
- but SUBCLINICAL INFECTION
- leukopenia
- thrombocytopenia
- transmitted by Dermacenter ticks
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Term
| structural/genetic characteristics of rubella |
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Definition
- aka german measles
- + ssRNA genomre
- single Ag type
- childhood infection
- congenital infection
- only member of rubivurs genus within togavirus family
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Term
| acquired rubella (german measles) (clinical manifestations, transmission) |
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Definition
- transmission- aerosolized particles
- infectivity from nasopharynx virus shedding
- contagious period 5 days before till 6 days after rash
- incubation period: 14-21 days
- characteristic clinical findings
- fever, arthralgias, sore throat
- rash
- face spreading downward
- erythematous maculopapular
- suboccipital adenopathy
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Term
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Definition
- virus isolation RARELY done
- rubella specific IgM
- more than 4 fold increase in IgG paired sera (acute and convalescent)
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Term
| congenital rubella (clinical manifestation/ characteristics) |
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Definition
- persistent, progressive infection
- fetal and placental infection occurs in first trimester maternal infection
- risk of infection and subsequent congenital defects is inversely related to gestational age
- fetal infection rates of 90% in first trimester
- virus induced progressive necrotizing vasculitis
- parenchymal hypoplasia
- extensive involvement of multiorgan
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Term
| classic congenital rubella infection clinical manifestations |
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Definition
- hepatosplenomegaly
- thrombocytopenic purpura
- dermal erythropoiesis (blueberry muffin)
- low birthweight
- end organ damage
- heart (PDA)
- eye (cataracts and retinopathy)
- auditory (deafness)
- brain (microcephaly, autism)
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Term
| rubella vaccine (type of injection, type of vaccine, side effects) |
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Definition
- subQ injection
- part of MMR
- live attenuated vaccine prepared in human diploid fibroblasts
- works by elicigting neutralizing Ab
- common side effect: mild rubella
- eliminated in US
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Term
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Definition
- rabies (genus: lyssavirus)
- vesicular stomatitis virus (genus: vesiculovirus)
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Term
| characteristics/structure/genetics of rabies/ lyssavirus |
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Definition
- enveloped virus
- type 1 is classic rabies (see type 4-6 in human cases as well)
- type 5 is european
- bullet shaped
- five structural proteins
- ss (-) RNA
- G protein spike that binds to cells
- replicate and assemble in cell cytoplasm
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Term
| rabies (mechanism of transmission, reservoirs) |
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Definition
- transmission via animal to human which causes acute encephalitis
- exposure to saliva
- virus in saliva attaches to peripheral nerve endings and travels to the brain
- in nature, rabies is disease of mammals (reservoirs)
- canines (virtually elim. in US)
- racoons
- mongooses
- skunks
- bats (causes most US cases)
- human rabies almost always secondary to animal bite
- rare exposure through inhalation or transplatation of corneas
- worldwide the major reservoir is dog
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Term
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Definition
- attacks nerves
- moves up spinal cord to brain
- this cause agitation, dementia, paralysis, and death
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Term
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Definition
- G: enveloped glycoprotein
- M- matrix envelope protein
- L- large, replicase
- N- nucleoprotein
- NS(P)- nonstructural protein
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Term
| replication of rabies virus |
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Definition
- enter cells by attaching to nicotinic ACh R followed by fusion event
- replication of virus in cytoplasmic inclusions (called Negri bodies)
- replicase copies ss (-) RNA produce ss + RNA than produce ss (-) RNA
- genes expressed in descending order
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Term
| different methods of transmission of rabies |
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Definition
- dogs (India, other developing countriews)
- wild animals
- bats (most common cause of transmission in US)
- usual leave unperceived bite sleeping persons
- vehicle is infected animal saliva
- bite or scratch or mucous membrane
- inhalation
- transplantation of cornea
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Term
| cellular pathogenesis of rabies |
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Definition
- after tissue exposure, rabies virus G protein attach to gangliosides on neuronal cells
- nicotinic ACh R
- peripheral N's and ascending at 100 mm/day
- CNS directly by aerosol into neuroepithelial cells of olfactory end organ
- no viremia
- spinal ganglia, virus replicates and spreads from cell to cell from spinal cord to brain
- minimal brain histologic damage in stark contrast to severity of clinical rabies
- Negri bodies = eosinophilic inclusions of rabies virus Ag's
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Term
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Definition
- incubation period (5 dys-2 yrs)
- prodrom (0-10 days)
- acute neurological (2-7 days)
- corna (5-14 days)
- death
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Term
| describe virus assembly that occurs at negri bodies with rabies |
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Definition
- virus assembly points within infected cell are called Negri bodies
- final envelopment (budding) will occur at the plasma membrane
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Term
| epidemiology of human rabies |
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Definition
- most cases in India
- mostly seen in children, majority male (rural boys in summer months)
- in US, most human rabies from bats
- most cases unperceived bites in sleeping individuals
- aerosol route in caves frequented by bats
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Term
| rabies: clinical manifestation stages |
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Definition
- assymptomatic phase
- nonspecific illness
- brain infection
- paralytic form after bat exposure mimicing Gillian Barre
- coma
- death via respiratory arrest or myocarditis
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Term
| rabies: clinical manifestations in asymptomatic phases |
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Definition
- prodromal period (2-10 days)
- viral invasion of CNS
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Term
| rabies: clinical manifestation in nonspecific illness stage |
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Definition
- can be resp. and GI
- behavioral and emotional changes
- limbic system, spinal cord, brain stem
- local pruritis, pain, paresthesia at inoculation site
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Term
| rabies: clinical manifestations in brain infection |
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Definition
- furious or hyperactive form
- aggressive (bittting, hitting, yelling)
- hyperactivity
- hallucinations
- triggered by sensory stimuli
- half experience hydrophobia or aerophobia
- violent diaphragmatic contractions
- exaggerated protective reflex
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Term
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Definition
- often misdx clinically
- CSF show signs of meningoencephalitis
- RT-PCR performed on saliva
- rabies specific Ab in serum or CSF measured by rapid fluorescent focus inhibition test
- Ab detected 6 days of onset of symptoms
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Term
| modern concepts of rabies immunology |
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Definition
-
relies of Ab to G protein of viral envelop
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Ab appear 7-14 dys after first dose
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booster dose at 21 days required
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with IM vaccination- 4 doses in first 2 weeks and 5th dose at 28 days or later
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intradermal regimes use muliple sites (2-8) administered on 4-5 occasions between days 0-90
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HIV infected patients respond poorly
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subjects older than 50 respond less well
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uncertain role of cellular immunity
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molecular mimicry of nicotinic R binding motife between rabies G protein and HIV gp120 leads to false positive HIV tests
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Term
| immunization schedules for postexposure |
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Definition
- rabies immune globin (RIG) on day 0
- cell culture vaccine on each of the days (0, 3, 7, 14, 28)
- 1 mL of vaccine is administered in deltoid
- in developing countries, this is not always practical
- intradermal to increase volume with fewer doses
- adverse rxns
- fevere
- HA
- insomnia
- palpitations
- diarrhea
- sensitization to proteins in older nerve tissue vaccines leads to allergic encephalomyelitis
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Term
| enzootic forms of rabies in north america |
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Definition
- racoon- east US
- skunk- midwest
- skunk- cali
- coyote- south TX, mexican border
- fox- SW, mexico border
- fox- northern NE, Canada
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Term
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Definition
- vaccination of domestic animals
- reduce spread of wild animals
- experimental bait vaccines (foxes, racoons, coyotes)
- eradicate infected animals
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