Exam IV Viruses Flashcards
influenza: hemagglutinin
- protein for cell attachment, sialic acid binding
- target of vaccines
influenza: transmission
- respiratory droplets
- very contagious in winter
influenza: natural reservoir
- infected humans
- pigs, birds can carry certain strains
influenza: pathogenesis
- incubates for 1-4 days
- viral shedding 1 day before onset of symptoms
- loss of ciliated and mucus producing cells
influenza: treatment
oseltamivir, zanamivir (tamiflu)
influenza symptoms
- acute onset w/ fever, cough, malaise, sore throat
- can get secondary bacterial pneumonia
influenza: prevention
- intramuscular vaccine: inactivated virus
- live attenuated nasal spray vaccine
influenza complications
- otitis media in children
- primary influenzal pneumonia (s. aureus)
- secondary bacterial or viral pneumonia (s. aureus, h. influenzae, s. pneumoniae)
- acute encephalopathy in children taking aspirin
parainfluenza: transmission
- respiratory droplets
- fomites
- aerosols
parainfluenza: natural reservoir
- infected humans
- ubiquitous: can exist on surfaces
parainfluenza: disease
acute laryngotracheobronchitis
- cold-like, bark-like cough, stridor and hoarseness
parainfluenza: ID
bark-like cough is confirmatory
- PCR can be done to rule out other causes
common cold: viruses
- rhinovirus: 30-50% of cases. 100s of serotypes of A, B, C
- coronavirus: 10-30% of cases. 2 serogroups, 4 strains
common cold: symptoms
nasal congestion, discharge, sore throat, fever, erythema of nasopharynx, oropharynx
common cold: risk factors/pathogenesis
- immunity is not useful due to 100s of serotypes
- many strains
common cold: natural reservoir, transmission
- humans
- respiratory secretions, close contact, aerosols
RSV: natural reservoir
humans
RSV: transmission
aerosols, fomites, nosocomial
RSV: ID
ELISA
RSV: diseases
- infant RSV: lower resp infections (bronchiolitis, pneumonia, tracheobronchitis,) (poor feeding, resp distress, fever, cough, hypoxemia)
- cold-like in adults
RSV: prevention
- isolation in hospital
- anti-sera for those exposed nosocomially
adenovirus: natural reservoir and transmission
- infected humans
- aerosols, fomites, fecal-oral
adenovirus: risk factors
- close quarters (military base, hospital)
- swimming pools
adenovirus: prevention
- good hygiene
- vaccine for military personnel only
adenovirus: pathogenesis
resistant to disinfectants, stable in GI tract
adenovirus: conjunctivitis
- epidemic keratoconjunctivitis
- adults and children get eye pain, inflammation, fever, preauricular lymphadenopathy
- pharyngoconjunctival fever
- conjunctivitis w/ pharyngitis
- epidemics in summer
herpesvirus: lytic infection
- lytic replication produces more viral particles, most viral genes are expressed
- produces progeny
- induces apoptosis of infected cell
herpesvirus drug target and drug
lytic cycle
- early stage: DNA synthesis
acyclovir
herpesvirus: latent infection
- latent infection maintains genome
- exists in equilibrium w/ host immune system
- type 1 establishes latency in trigeminal ganglia, type 2 establishes latency in sacral ganglia
herpesvirus: encoded proteins
- DNA polymerase and terminase: successful drug targets
- thymidine kinase: successful drug targeth
HSV 1, 2: pathogenesis
- primary infection is of mucosal surfaces: limited by IFN, innate response
- cell-cell spread to immune, neuronal cells
- establishes latency in nucleus of nerves
HSV 1, 2: symptoms
vesicular lesion that is wet, then crusts over and can ulcerate
HSV 1, 2: natural reservoir, transmission
- infected humans
- type 1 is oral contact: sharing contaminated items
- type 2 is sexual contact
HSV 1, 2: ID
- cytology of lesions
- PCR
- culture, IF
- serology for prior exposure
HSV 1, 2: prevention
-safe sex
- C-section for pregnant mother for active lesions
herpes labialis
HSV 1, 2
cold sores: pain, itching, tingling before lesion appears
herpes gingivostomatitis
HSV 1 for toddlers and children, either 1 or 2 for adults
- pharyngeal erythema, edema, clear pharyngeal and buccal vesicles that ulcerate rapidly
herpes gladiatorum
HSV 1 or 2
- infection from cuts, abrasions on face/chest
- common in wrestlers, rugby players
herpes whitlow
HSV 1
- inoculation of finger, can be mistaken for paronychia
herpes meningitis
- common in primary infection, especially in women
- fever, headache, photophobia, nuchal rigitidy
- aseptic: usually HSV2
herpes encephalitis
- rare but serious
- CSF w/ elevated protein, pleocytosis, erythrocytosis
- alteration in mental status
varicella-zoster: pathogenesis, latency
- infection of upper resp tract
- replication in lymph nodes
- replication in secondary lymphoid organs
- replication in skin
latency in neurons
varicella-zoster: natural reservoir, transmission
- infected humans
- from aerosols, skin
varicella-zoster: risks, prevention
- risk to those unvaccinated
- shigrix vaccine: subunit
- varicella vaccine: live-attenuated
chicken pox + complications
- varicella causes
- mostly in children
- complications: varicella pneumonia, encephalitis, neonatal varicella
shingles
- zoster causes
- reactivation in adults
- neuralgia, pain, burning, itching
epstein-barr virus: pathogenesis, latency
- B-cells are latently infected, inducing immune response
- EBV nuclear antigens and latent membrane proteins are expressed in human cancers
epstein-barr virus: ID
- monospot test: heterophile antibodies
- uses latex bead agglutination
- older technique: blood smear w/ atypical lymphocytes
epstein-barr virus: reservoir, transmission, prevention
- infected humans
- spread through saliva
- standard hygiene for prevention
EBV and cancer
- nasopharyngeal carcinoma and Burkitt’s lymphoma are endemic
- Hodgkin’s lymphoma
mononucleosis: cause, symptoms
- EBV
- high fever, malaise, pharyngitis, fatigue, lymphadenopathy, hepatosplenomegaly
human herpesvirus 6A, 6B, 7: reservoir, transmission
- infected humans
- direct contact
human herpesvirus 6A, 6B, 7: disease
roseola
cytomegalovirus: reservoir, transmission, risks
- infected humans
- spread through direct contact
- transplant complication
cytomegalovirus: treatment
gancyclovir
cytomegalovirus: latency
- in epithelial cells
- can be reactivated by T-cell immunity breakdown
cytomegalovirus: ID
- CMV-specific serology
- 4-fold increase in CMV-specific IgG titers
cytomegalovirus: diseases
- heterophile - mono
- cytomegalic inclusion disease in infants: hearing loss, microcephaly, intracerebral calcification
- multi-site symptomatic disease in HIV patients
kaposi’s sarcoma-associated herpesvirus : reservoir, transmission, risks
- infected humans
- spreads through saliva, blood, sexually
- immunosuppressed at risk, higher seropositivity in Africa
kaposi’s sarcoma
- infects endothelial cells
- polyclonal, multifocal lesions
acute hepatitis
- lasts less than 6 months
- rarely causes hepatic failure
- increased serum aminotransferases x1000
chronic hepatitis
- more than 6 months
- starts mild, but liver can fail
- increased serum aminotransferase x100
- decreased albumin, increased clotting time
hepatitis A: natural reservoir, transmission, risks
- infected humans, contaminated water, shellfish
- fecal-oral transmission
- risk is raw seafood ingestion
hepatitis A: prevention
vaccine w/ neutralizing antibodies
hepatitis A, E: diagnosis
serology: IgM appearance
IgG indicates prior infection or vaccination
hepatitis A, E: disease
acute hepatitis
hepatitis E: reservoir, transmission, risks
- infected humans, contaminated water, can be in pigs
- fecal-oral
- more likely in underdeveloped nations
hepatitis B, D: reservoir, transmission, risks
- infected humans’ blood, fluids
- spread through contact w/ blood or fluid: IV drug use, sex, mother to baby
hepatitis B, D: treatment, prevention
-entecavir
- recombinant subunit vaccine for prevention
hepatitis B: diagnosis (antigens, antibodies)
Ag-Ab tests
- HBsAg+ and DNA + = active infection
- Anti-HbS+ and DNA- = cured
- HBeAg shows higher infectivity
hepatitis B: diseases
neonatal hepatitis: almost always chronic. asymptomatic early in life, complications arise later
hepatitis D: pathogenesis
- new host has to be HBV+
- requires HBV’s HBsAg
HBV + HDV coinfection vs superinfection
coinfection: severe acute
superinfection: chronic
hepatitis C: natural reservoir, transmission, risks
- infected humans’ blood, fluid
- bloodborne
- IV drug use, contaminated tattoo, piercing
hepatitis C treatments
- sofosbuvir + velpatasvir for polymerase
- glecaprevir + pibrentasvir for protease
hepatitis C ID
antibody blood test
if positive: RNA test
measles: reservoir, transmission, risks
- infected humans
- spread through direct contact, resp. droplets, fomites
- risk to those unvaccinated
hepatitis C diseases
usually asymptomatic
- chronic HCV similar to HBV
measles: prevention
live attenuated vaccine
measles: diagnosis
- cough, coryza, conjunctivitis
- koplik’s spots
- IgM, RNA
measles, mumps, rubella, smallpox: pathogenesis
- replication in upper resp tract
- infection of local lymphatic tissues
- viremia
- spread to other systems
measles: complications
- major cause of childhood blindness in developing countries
- pneumonia is usually the fatal complication in children
- otitis media
- encephalitis
mumps, rubella: reservoir, transmission, risks
- infected humans
- resp droplets
- risk to those unvaccinated
mumps: symptoms
swollen, puffy cheeks (from swollen salivary glands)
HPV pathogenesis
- virus travels to basal layer
- viral DNA replicated in basal layer - differentiating keratinocytes re-enter S phase: epidermis thickens
- late genes expressed in granular, cornified layers: package viral DNA
HPV: cancer association
cervical cancer
- second most common cause of death in women
- abnormal squamous cells found in pap smear
- from high risk genotypes: usually 16 or 18
- virus must be integrated into chromosome
HPV: treatments and target
imiquimod: targets TLR7, activating macrophage secretion of pro-inflammatory cytokines
podophyllotoxin: binds microtubules, inhibiting polymerization –> mitotic arrest
HPV: prevention
- 9 valent vaccine for high-risk types
- cervical cancer vaccine induces high titers of neutralizing ABs
- subunit vaccine w/ major capsid protein
HPV: transmission
- direct contact
- sexual contact
poliovirus: prevention
- no recent cases in the US
- inactivated intramuscular vaccine: prevents paralytic poliomyelitis
- oral vaccine: prevents local, CNS infection
polio: major illnesses
- serious aseptic meningitis, poliomyelitis
- paralysis
non-polio enteroviruses: transmission, common diseases
- second most infectious virus
- resp. secretions, direct contact, exists on surfaces
- summer cold
enteroviruses neurological diseases
paralytic: polio
meningitis: all enteroviruses can cause
encephalitis: not common
herpangina
- group A coxsackie
- sore throat w/ grayish-white ulcers
hand-foot-mouth disease
- group A coxsackie
- sore throat w/ vesicles, bullae
- rash
HIV acute infection: clinical and lab findings, course
- non-specific signs, symptoms: headache, muscle aches, sore throat, lymphadenopathy
- decreasing CD4/CD8 ratio, lymphopenia
- course: lasts for weeks, lymphadenopathy and malaise for months
HIV asymptomatic period
clinical latency: viral replication in lymph nodes, gradual CD4 depletion
HIV immunodeficiency
- susceptibility to opportunistic infections
- impaired ability to mount immune response to new antigen, maintain memory response
HIV common opportunistic infections
- Tb, salmonella, legionella, candida, histoplasmosis, toxoplasmosis, leishmania
- EBV lymphomas, KSHV sarcoma
HIV macrophage infection
CCR5
- binds CD4, then looks for and binds co-receptors
- typically transmitted version
HIV T cell infection
- CXCR4 T cell infection
- shift to T cell infection is associated w/ disease progression
HIV treatment
- anti-retroviral therapy (HAART)
- polymerase inhibitor, protease inhibitor, fusion or integrase inhibitor
HIV prevention
emtricitabine-tenofovir used prophylactically
- nucleoside reverse transcriptase inhibitor
HIV diagnosis
- antigen-antibody test
- 1/2 differentiation assay
- if diagnosed: HIV viral load, CD4 count
rabies: reservoir, transmission, risks
- foxes, skunks, dogs, raccoons, bats
- bite transmission
- worldwide: most deaths from canine transmission
rabies: pathogenesis
- viral replication in inoculation site
- virus enters PNS via neuromuscular junction
- spreads to CNS
- spreads along nerves to glands, tissues
rabies: phases
- incubation: 2 weeks - 18 months
- prodromal phase: 1 week, nonspecific symptoms
- rabid phase: neurological symptoms
rabies: ID
- rapid virus antigen: skin biopsy
- PCR saliva
- post mortem histopathology for negri bodies
rabies: treatment, prevention
- post-exposure prophylaxis, antibody therapy w/ rabies immune globulin
- pre-exposure prophylaxis
arboviruses: urban cycle + diseases
- man to arthropod to man
- dengue, yellow fever
arboviruses: sylvatic cycle + diseases
- animal to arthropod to animal
- humans infected incidentally
- yellow fever, west nile
arbovirus: pathogenesis
- virus introduced through bite
- local replication
- virus disseminates, replicates in specific tissues
- crosses blood brain barrier
- neuron infection
arboviruses: ID
- serology: IgM in CSF is diagnostic
- PCR for viral nucleic acids
arboviruses: symptoms, diseases
- often subclinical
- viremia
- arbovirus encephalitis
west nile virus: transmission, reservoir, risks
- in birds
- transmitted through mosquito bite
- increasing prevalence in US
dengue: diseases
- dengue hemorrhagic fever: hemorrhagic fever and shock
- if exposed to one type, antibodies can help another type infect
- break bone fever
ebola: reservoir, transmission
- bats
- nosocomial, blood and sexual contact
