Viruses Flashcards
herpes simplex virus 1
features / diseases
DNA enveloped herpes labialis - waist up eicosahedrical core latent cold sores, corneal ulcers, encephalitis, neonatal herpes
herpes simplex virus 1
pathogenesis
lytic in epithelial cells vesicular rash (lips and nose) lysogenic in trigeminal ganglia no integration herpatic neuritis herpes whitlow
herpes simplex virus 1
transmission
saliva
80% americans, 40% recurrent
60% asymptomatic
herpes simplex virus 1
prevention / treatment
avoid contact with lesions
antiviral
herpes simplex virus 2
features / diseases
DNA enveloped herpes genitalis - waist down eicosahedrical core latent neonatal herpes
herpes simplex virus 2
pathogenesis
lytic in epithelial vesicular rash (genitals) lysogenic in sacral ganglia no integration herpatic neuritis herpes whitlow
herpes simplex virus 2
transmission
sexual contact
herpes simplex virus 2
prevention / treatment
avoid contact with lesions
antiviral
varicella - zoster
features / diseases
DNA enveloped latent (same as herpes) chicken pox shingles viremia systemic infection
varicella - zoster
pathogenesis
same as herpes
no integration
repetitive shingles in elderly, can lead to neuritis
varicella - zoster
transmission
respiratory droplets
varicella - zoster
prevention / treatment
live attenuated virus vaccine
avoid contact with lesions
no drugs necessary if immunocompetent
antivirals
epstein barr virus
features / diseases
DNA enveloped
acute / latent
infectious mononucleosis
lymphomas and cancer
epstein barr virus
pathogenesis
integration
60-70% asymptomatic
sometimes symptoms for up to 1 year
increased number of lymphocytes is a sign
tonsils/spleen become enlarged, can cause strep
infects WBCs
epstein barr virus
transmission
saliva
epstein barr virus
prevention / treatment
don’t share food/ kiss infected person
spontaneous recovery
cytomegalovirus
features / diseases
DNA enveloped
most common cause of congenital abnormalities
acute / latent
fever, lethargy in healthy
pneumonia, hepatitis, retinitis in immunocomp
cytomegalovirus
pathogenesis
lytic in epithelial cells
lysogenic in neurons and WBCs
no integration
histology- owl eye inclusion
cytomegalovirus
transmission
early- placenta
children- saliva
adults- sexual contact
80% of adults have had contact
cytomegalovirus
prevention / treatment
pregnant women without CMV stay away from kids
exposure before pregnancy does not transfer to baby
isolation of shedding individuals
antivirals (same as herpes)
herpes virus 8
features / diseases
DNA enveloped
latent
Kaposi’s sarcoma
herpes virus 8
pathogenesis
lysogeny in neurons and WBCs
integration
sometimes asymptomatic
herpes virus 8
transmission
saliva
increased risk if immunocomp (HIV)
5-20% incidence
herpes virus 8
prevention / treatment
avoid direct contact
chemotherapy
antivirals
papillomavirus (HPV)
features / diseases
DNA non-enveloped chronic 100 types of virus (30 genital, 70 skin) papillomas: benign skin tumor, genital warts cervical/ penis cancers
papillomavirus (HPV)
pathogenesis
slow replication
hard to grow in lab
lysogeny with integration
inhibits checkpoint proteins in cell cycle
HPV 16/18 inactivate tumor suppressor genes (p53, Rb), increase risk of mutations
increase in number and size of lesions increases risk of cancer
80% of cases are single small lesions
papillomavirus (HPV)
transmission
skin to skin contact
genital contact
papillomavirus (HPV)
prevention / treatment
vaccine (3 doses)
antivirals
liquid nitrogen for lesions
influenza
features / diseases
RNA enveloped
genome in 8 segments
hemagglutinin (16) and neuraminidase (9) in envelope
acute
animals and humans
respiratory infection only
(A- most common, humans, can cause pandemic
B- limited epidemics in humans
C- mostly in animals)
seasonal flu
pandemic flu (every 20 years, killed 4% world pop in 1918)
influenza
pathogenesis
replicates in nucleus
lytic in lungs
antigenic shift: avian flu + regular flu -> new deadly virus
host immune response worse than infection
influenza
transmission
airborne droplets
influenza
prevention / treatment
vaccine (2 A, 1 B isolates)
tamiflu (some A’s resistant)
mumps
features / diseases
RNA enveloped
non-segmented genome
paramyxovirus
mumps- parotid gland swelling
mumps
pathogenesis
upper respiratory tract first
viremia
to parotid, testes/ ovaries, pancreas
mumps
transmission
respiratory droplets
highest spread in winter
mumps
prevention / treatment
live attenuated vaccine
lifelong immunity
no treatment
measles
features / disesases
RNA enveloped non-segmented genome single stranded RNA (negative) paramyxovirus measles
measles
pathogenesis
lytic in immune cells
viremia to skin
starts in upper respiratory tract
rash caused by cytotoxic T clls
measles
transmission
airborne droplets
30 million cases/year worldwide
causes epidemics
measles
prevention / treatment
live attenuated vaccine
lifelong immunity
no treatment
rubella
features / diseases
RNA enveloped
single stranded RNA (positive)
togavirus
rubella and congenital rubella syndrome
rubella
transmission
airborne droplets
transplacenta
eliminated from US
rubella
pathogenesis
lytic in nasopharynx and lymph nodes
spreads via blood to organs and skin
rubella
prevention / treatement
live attenuated vaccine
lifelong immunity
no treatment
human immunodeficiency virus
features / diseases
lentivirus (retrovirus) single stranded RNA has GP120 and GP41 glycoproteins to regulate inflammation = GP120 attacks CD4 cells = CP31 attacks CCR5, CXCR4 diploid virus HIV-1, HIV-2
human immunodeficiency virus
pathogenesis
infects WBCs, destroys helper T cells lysogeny- hides in host chromosome integration steps: 1. virus fuses, enters cell 2. reverse transcriptase converts RNA to DNA 3. DNA becomes double stranded 4. DNA carried into nucleus by integrase (lysogeny) 5. copies make viral RNA and mRNA 6. protease breaks DNA to make proteins 7. viral assembly and budding healthy: 120-1500 CD4 cells/ul AIDS: 200-500 CD4 cells/ul acute retroviral syndrome: 3 months asymptomatic: 7-10 years, decrease 50 CD4 cells/ year AIDS: several years until death
human immunodeficiency virus
transmission
unprotected sex (receptive and anal are riskier)
other STDs increases risk
sharing needles
transplacental
human immunodeficiency virus
prevention / treatment
condoms
reverse transcriptase or protease inhibitors in cocktail of drugs
rotavirus
features / diseases
RNA non-enveloped
gastroenteritis
most common cause of gastroenteritis in children
rotavirus
pathogenesis
lytic in intestinal tissue
causes lesions in intestines
diarrhea
rotavirus
transmission
fecal oral (water)
rotavirus
prevention / treatment
vaccine (esp for kids in developing countries)
personal hygiene
water treatment
self-resolving
norovirus
features / diseases
RNA non-enveloped
gastroenteritis (“stomach flu”)
most common viral gastroenteritis in adults
norovirus
pathogenesis
lytic in intestinal tissue
causes lesions in intestines
diarrhea
norovirus
transmission
fecal oral (water) cruise ships
norovirus
prevention / treatment
personal hygiene
water treatment
self-resolving
rhinovirus
features / disesases
RNA non-enveloped 100+ types in upper respiratory tract mild resistance to detergents/ bases susceptible to acid common cold
rhinovirus
pathogenesis
lytic in lungs
rhinovirus
transmission
airborne droplets hands can survive in environment for a few days via fomites americans have 3 infections / year
rhinovirus
prevention / treatment
wash hands
no vaccine because too many types
symptomatic treatment
hepatitis (all types)
symptoms
inflammation of liver jaundice hemoglobin -> bilirubin, biliverdin recycling liver inflam -> deposit intermediates in liver -> jaundice fever lack of appetite nausea dark urine pale feces infection resolves in 2-4 weeks
hepatitis A
features
RNA non-enveloped enterovirus acute denatured capsid proteins by boiling survives weeks in environment and stomach
hepatitis A
pathogenesis
infects enterocytes, also mouth and throat
spreads through blood to liver
lytic in liver
cleared by infected cells, can cause further damage
no chronic infection
hepatitis A
transmission
fecal oral direct or indirect contact sometimes saliva 50% US pop exposed, 90% developing countries low mortality
hepatitis A
prevention / treatment
formaldehyde killed vaccine travelers, children, anal-oral sex proper hygiene sewage disposal no antivirals lifetime immunity
hepatitis B
features
DNA enveloped
double stranded DNA
in liver cells
hepatitis B
pathogenesis
RNA -> DNA with reverse transcriptase DNA -> viral proteins sometimes lysogeny with integration DNA -> viral DNA polymerase -> DNA lytic in liver cells
hepatitis B
transmission
blood sex during birth direct transmission only asians more susceptible 90% infected neonate -> chronic carriers cirrhosis: liver tissue replaced by scar tissue; or liver failure or cancer
hepatitis B
prevention / treatment
virus subunits vaccine
health professionals, STDs, IV users, transfusions
treatment only for chronic carriers
alpha interferon
inhibitors of reverse transcriptase and viral DNA polymerase
hepatitis C
features
RNA enveloped single stranded RNA hypervariable genome in liver cells persistant chronic
hepatitis C
pathologenesis
RNA -> DNA reverse transcriptase
lysogeny with integration
hard to control replication because virus keeps changing
immune system attacks
alcoholism increases disease
75% infected become chronic carriers
10% of cases cause cancer, cirrhosis, liver failure
hepatitis C
transmission
blood transfusion
rare: sex or during birth
4 million americans infected
direct contact only
hepatitis C
prevention / treatment
avoid blood contact (drug users)
alpha interferon
reverse transcriptase inhibitors
new drugs with 50%+ cure rate
hepatitis D
features
RNA enveloped defective virus only infects HBV individuals no capsid protein genome persistant chronic
hepatitis D
pathogenesis
uses capsid of HBV
increases liver damage speed
hepatitis D
transmission
same as HBV
direct contact
hepatitis D
prevention / treatment
prevent HBV
no treatment
hepatitis E
features
RNA non-enveloped
acute
major cause of enteric transmitted hepatitis in asia, africa, india, mexico, but rare in US (diff from HAV)
can infect pigs
hepatitis E
pathogenesis
20% infected pregnant women -> fatal hepatitis (75% mortality)
hepatitis E
transmission
fecal oral
same as HAV
direct and indirect contact
hepatitis E
prevention / treatment
vaccine
avoid contaminated water/food
no treatment
