Microbiology - Virus Flashcards
Adenovirus
Non-enveloped, linear dsDNA virus
Causes febrile pharyngitis, conjuctivitis, ARD, pneumonia, infectious keratitis, otitis media, sinusitis, acute hemorrhagic cystitis
Adenovirus (types 40 and 41)
Causes secretory protracted (1-2 weeks) diarrhea in children
All DNA viruses are double stranded with which exception?
Parvovirus is single stranded DNA (e.g. parvovirus B19) → replicates in the cytosol
All dsDNA viruses (except HBV) are infectious when purified → replicates in the nucleus
All RNA viruses are single stranded with the exception of…
Reovirus are double stranded RNA (e.g. rotavirus, coltivirus)
All RNA viruses replicate in the cytosol (except influenza virus and retroviruses)
BK virus
Polyomavirus
Non-enveloped, circular dsDNA virus
Seen in transplant patients, commonly targets the kidney
California encephalitis
Bunyavirus
Enveloped, helical, 3 segments of circular -ssRNA
Colorado tick fever virus
Reovirus 12 segments of dsRNA Not enveloped Wood tick
Crimean-Congo Hemorrhagic Fever
Bunyavirus
Enveloped, helical, 3 segments of circular -ssRNA
Hemorrhagic fever
Tx: ribavirin
Coronavirus
Coronavirus
Enveloped, helical, linear +ssRNA
Common cold
SARS (a/w masked palm civets, bats, ARDS, atypical pneumonia)
MERS (a/w camels)
Coxsackievirus
Picornavirus
Non-enveloped, icosahedral, linear +ssRNA
Type A causes herpangina, hand, foot, and mouth disease (rash on palms and soles), conjuctivitis
Type B causes pleurodynia
Either type can cause aseptic meningitis, myocarditis, pericarditis
Cytomegalovirus (CMV)/HHV-5
Herpesvirus
Enveloped, linear dsDNA virus
Atypical pneumonia, esophagitis (linear ulcerations in esophagus) in the immunosuppressed, retinitis (cotton-wool spots on funduscopic exam), mononucleosis-like syndrome (fever, fatigue, splenomegaly, aytpical lymphocytes ± sore throat, lymphadenopathy), congenital infection (periventricular calcifications, sensorineural hearing loss, seizures, blueberry muffin rash)
Nuclear and cytoplasmic inclusions in infected cells → “Owl Eyes” (see picture); latent in mononuclear cells
Binds to cellular integrins
No agglutination with serum heterophile antibodies (e.g. negative Monospot)
Tx: ganciclovir
Dengue
Flavivirus
Enveloped, icosahedral, linear +ssRNA
Bite of Aedes aegypti mosquito (arbovirus)
Infection with more than one of the 4 serotypes → hemorrhagic fever
Eastern/Western equine encephalitis
Togavirus
Enveloped, icosahedral, linear +ssRNA
Arbovirus
Ebola Virus
Marburg Virus
Filovirus
Enveloped, helical, linear -ssRNA
Pleomorphic shape
Hemorrhagic fever → often fatal
Epstein-Barr Virus (EBV)/HHV-4
Herpesvirus
Enveloped, linear dsDNA virus
Binds to CR2 (CD21)
Causes mononucleosis (fever, fatigue, hepatosplenomegaly, infects B cells but aytpical lymphocytes = cytotoxic T cells, exudative pharyngitis, cervical lymphadenopathy, esp. posterior cervical chain), endemic Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma
Agglutination with serum heterophile (horse, sheep) antibodies (e.g. Monospot); infection produces cold agglutinins
Risk of splenic rupture → avoid contact sports for 3 weeks
Equine Encephalitis
Togavirus
Enveloped, icosahedral, linear +ssRNA
Culex mosquito (arbovirus)
Flu-like illness, encephalitis
For which viruses are there live attenuated vaccines?
Live attenuated vaccines induce humoral and cell-mediated immunity but have a risk of reverting to virulence → no booster needed but avoid in immunocompromised and their close contacts
Vaccinia
Polio (Sabin)
Yellow fever
Measles, Mumps, Rubella
Rotavirus
Adenovirus
Varicella/Zoster
Small pox
Intranasal influenza
From which viruses are there killed vaccines?
Rabies
Polio (Salk = killed)
Influenza (injected)
Hepatitis A
Japanese encephalitis
From which viruses are there recomginant vaccines?
Hepatitis B (recombinant HBsAg)
HPV (types 6, 11, 16, 18)
Hantavirus
Bunyavirus
Enveloped, helical, 3 segments of circular -ssRNA
Contact with rodents
Hemorrhagic fever, pneumonia
Hepatitis A virus (HAV)
Picornavirus
Non-enveloped, icosahedral, linear +ssRNA
Fecal-oral transmission
Causes acute viral hepatitis
No carrier status or increased risk of hepatocellular carcinoma
Hepatitis B virus (HBV)
Hepadnavirus
Enveloped, circular dsDNA virus
Parenteral, sexual, maternal-fetal transmission
HBV DNA polymerase completes partial dsDNA → incorporated into host genome → host RNA polymerase makes mRNA → HBV DNA polymerase reverse transcribes mRNA into DNA to form new viral particle
Causes acute and chronic hepatitis; viral genome integrates into host genome → ↑ risk of hepatocellular carcinoma
Hepatitis C virus (HCV)
Flavivirus
Enveloped, icosahedral, linear +ssRNA
RNA-dependent RNA polymerase has no proof reading 3’→5’ exonuclear activity → mutations in envelope glycoproteins prevent immunity from infection or vaccines
Transmitted via blood (IVDU, post-transfusion), sex
Causes chronic inflammation → cirrhosis, hepatocellular carcinoma
Tx: INFα, ribavirin, sofosbuvir
Hepatitis D virus (HDV)
Delta virus
Enveloped, uncertain capsid shape, circular -ssRNA
Parenteral, sexual, maternal-fetal transmission
D for defective (requires HBV co-infection)
Superinfection (HDV following HBV) decreases prognosis
HDV must be coated by HBsAg to penetrate the hepatocyte
Hepatitis E virus (HEV)
Hepevirus
Non-enveloped, icosahedral, linear +ssRNA
Fecal-oral transmission, esp with water-borne epidemics
High mortality in pregnant women
Herpes Simplex Virus (HSV)
Herpesvirus
Enveloped, linear dsDNA virus
Infects mucosa epithelial cells → gingivostomatitis, herpes labialis, herpes genitalis, spontaneous temporal lobe encephalitis, keratoconjunctivitis, neonatal herpes (vesicular lesions, encephalitis)
Latent in trigeminal ganglia or sacral ganglia
Dx: viral culture, PCR of CSF, intranuclear Cowdry A inclusions, Tzanck smear (genital) showing multinucleated giant cells (see picuture)
Tx: acyclovir, ganciclovir
HHV-8
Herpesvirus
Enveloped, linear ds DNA virus
Causes Kaposi sarcoma, neoplasm of endothelial cells (biopsy reveals lymphocytic inflammation)
Transmitted sexually
How to distinguish maculopapular rash of rubella from measles
Both rashes start in the face and spread downward
Rubella rash involves the trunk
Measles rash involves the trunk and limbs
HTLV
Retrovirus → reverse transcriptase
Enveloped, icosahedral, linear +ssRNA
Causes T-cell leukemia
Human Immunodeficiency Virus (HIV)
Retrovirus → reverse transcriptase
Enveloped, conical, 2 copies of linear +ssRNA
Viral gp120 targets CD4 and CCR5 (early) or CXCR4 (late) receptors on CD4+ T cells; targets CD4 and CCR5 on macrophages
Causes AIDS when CD4 count < 200 or HIV + AID-defining illness or CD4 % < 14%
Dx: ELISA (high sensitivity) if + → Western blot (high specificity)
Human Papilloma Virus (HPV)
Papillomavirus
Non-enveloped, circular dsDNA virus
HPV 1, 2, 6, 11 cause condylomata acuminata
HPV 16, 18, 31 cause cancer of the cervix, penis, anus; virus expresses E6 and E7 which inactivates p53 and Rb, respectively, stimulating cell growth
Influenza virus
Orthomyxovirus
Enveloped, helical, segmented linear -ssRNA
Hemagglutinin promotes viral entry
Neuraminidase promotes progeny virion release
Patients at risk for fatal bacterial superinfection
Japanese Encephalitis
Flavivirus
Enveloped, icosahedral, linear +ssRNA
Birds and pigs are reservoirs
Bite of Culex mosquito (arbovirus)
Encephalitis Vaccine
JC Virus
Polyomavirus
Non-enveloped, circular dsDNA
Progresses to multifocal leukoencephalopathy (PML) in HIV
Lassa fever
Arenavirus –> grainy appearance
Enveloped, helical, 2 segments of circular -ssRNA
Contact with mice/rats in W. Africa
Hemorrhagic fever, hearing loss, pregnancy complications
Lymphocytic choriomeningitis virus (LCMV)
Arenavirus –> grainy appearance
Enveloped, helical, 2 segments of circular -ssRNA
Contact with mouse, hamster excreta
Biphasic illness
Measles
Paramyxovirus
Enveloped, helical, linear -ssRNA
F (fusion protein) causes respiratory epithelial cells to fuse (syncitia)
3 C’s of measles: cough, coryza (catarrhal inflammation of the mucous membrane in the nose), conjunctivitis
Koplik spots (red spots with blue-white center on buccal mucosa) precede descending maculopapular rash that involves trunk and limbs (CTL response)
Sequelae include: post-infectious encephalitis, acute disseminated encephalomyelitis (ADEM), measles inclusion body encephalitis (MIBE), subacute sclerosing panencephalitis (SSPE), giant cell pneumonia (in immunosuppressed/malnourished)
MMR Vaccine
Live-attenuated vaccine against measles, mumps, and rubella
Rubella component may induce arthralgias
Molluscum contagiosum
Poxvirus → only type of DNA virus that replicates in the cytoplasm (has own DNA-dependent RNA polymerase)
Enveloped, linear dsDNA virus
Spreads in pools, gyms
Flesh-colored dome lesions with central umbilicated dimple (see picture)
Large eosinophilic cytoplsmic inclusions called molluscum bodies
Mumps
Paramyxovirus
Enveloped, helical, linear -ssRNA
F (fusion protein) causes respiratory epithelial cells to fuse (syncitia)
Causes parotitis (elevated amylase), orchitis (usually unilateral, can cause infertility in teenagers), meningitis
Nipah/Hendra virus
Paramyxovirus
Enveloped, helical, linear -ssRNA
a/w bats, horses
Norovirus
Calcicivirus
Non-enveloped, icosahedral, linear +ssRNA
Leading cause of food borne disease
Causes secretory diarrhea and vomiting
More prevalent in older children and adults
Parainfluenza
Paramyxovirus
Enveloped, helical, linear -ssRNA
F (fusion protein) causes respiratory epithelial cells to fuse (syncitia)
Causes croup (seal-like barking cough)
Autumn epidemic
Parvovirus B19
Parvovirus
Non-enveloped, linear ssDNA virus
Transmitted through respiratory droplets and infects RBC precursors
Causes erythema infectiosum (prodrome → slapped cheek rash → lacy, reticular rash on trunk, extremities), aplastic crisis in people with chronic hemolytic anemia/sickle cell disease, hydrops fetalis, polyarthritis (esp. in adult women)
Can cross placenta
Polio virus
Picornavirus
Non-enveloped, icosahedral, linear +ssRNA
Salk/IPV killed vaccine
Sabin/OPV live vaccine
Rabies
Rhabdovirus
Enveloped, helical, linear -ssRNA
Binds to nicotinic acetylcholine receptors → retrograde travel through peripheral neurons to CNS
Bullet-shaped Negri bodies in Purkinje cells of the cerebellum and hippocampus (show picture)
Fever, malaise → agitation, photophobia, hydrophobia → paralysis, coma → death
Respiratory Syncytial Virus (RSV)
Paramyxovirus
Enveloped, helical, linear -ssRNA
F (fusion protein) causes respiratory epithelial cells to fuse (syncitia)
Causes URI, croup, bronchiolitis, pneumonia in infants
Winter epidemic
Tx: ribavirin, palivizumab (Ab against F protein) prevents pneumonia caused by RSV in premature infants
Rhinovirus
Picornavirus
Non-enveloped, icosahedral, linear +ssRNA
Causes the common cold
Roseola/HHV-6
Herpesvirus
Enveloped, linear dsDNA virus
High fevers for several days that can cause seizures followed by a diffuse maculopapular rash
Rotavirus
Reovirus
Non-enveloped, double icosahedral, segmented linear dsRNA
Most common cause of infantile diarrhea (secretory); villous destruction with atrophy leads to decreased absorption of sodium and loss of potassium
Winter seasonal pattern
Reassortment (due to segmented genome) between related species can cause new strains
Rubella virus
Togavirus
Enveloped, icosahedral, linear +ssRNA
pH-dependent endocytosis
Causes fever, postauricular lymphadenopathy, arthralgias, and fine rash that starts on the face and spreads to the trunk (first manifestation)
Can cause TORCH infection in newborns (transplancental, esp. 1st trimester) –> PDA/pulmonary artery hypoplasia, cataracts, deafness ± blueberry muffin rash
Diagnose with nasal culture
Sandfly/Rift Valley fever
Bunyavirus
Enveloped, helical, 3 segments of circular -ssRNA
Smallpox
Poxvirus
Enveloped, linear dsDNA virus
Brick-shaped virions
Currently eradicated but can be used in germ warfare
St. Louis encephalitis
Flavivirus
Enveloped, icosahedral, linear +ssRNA
Arbovirus
Varicella Zoster Virus (VZV)/HHV-3
Herpesvirus
Enveloped, linear dsDNA virus
Primary infection = chickenpox; vesicular lesions of different ages that starts on the trunk and spreads to face and extremities
Recurrent infection = shingles; vesicular lesions in dermatomal distribution → post-herpetic neuralgia
Latent in dorsal root or trigeminal ganglia
West Nile Virus
Flavivirus
Enveloped, icosahedral, linear +ssRNA
Birds are reservoir, bite of Culex mosquito (arbovirus)
Flu-like symptoms, encephalitis
What viruses are associated with a maculopapular rash?
Measles Rubella Scarlet fever Roseola Parvovirus B19 Rash-associated enteroviruses
Which RNA viruses are positive-stranded ssRNA?
+ssRNA ≈ mRNA and are infectious when purified
Retrovirus
Togavirus
Flavivirus
Coronavirus
Hepevirus
Calcicivirus
Picornavirus
“I went to a retro toga party where I drank flavored Corona and ate hippy California pickles”
Yellow fever
Flavivirus
Enveloped, icosahedral, linear +ssRNA
Aedes aegypti mosquito bite (arbovirus)
High fever, black vomit, jaundice
Live attenuated vaccine
What respiratory infections are associated with AIDS?
CMV pneumonia Aspergilllosis Pneumocystis peumonia –> Pneumocystis jirovecii Pneumonia –> S. pneumoniae TB-like disease –> Mycobacterium avium-intracellulare (Mycobacterium avium complex [MAC])
What respiratory infections are associated with AIDS?
CMV pneumonia Aspergilllosis Pneumocystis peumonia –> Pneumocystis jirovecii Pneumonia –> S. pneumoniae TB-like disease –> Mycobacterium avium-intracellulare (Mycobacterium avium complex [MAC])
What are dermatologic infections associated with AIDS?
Candidiasis of mouth, esophagus Hairy leukoplakia on lateral tongue –> EBV Bacillary angiomatosis –> Bartonella henselae
What are neurologic infections associated with AIDS?
Ring-enhancing lesions –> Toxoplasma gondii Dementia Encephalopathy –> JC virus reactivation Meningitis –> cryptococcus neoformans Retinitis –> CMV (cotton-wool spots)
What are oncologic disease associated with AIDS?
Non-Hodgkin lymphoma –> EBV Primary CNS lymphoma –> EBV Squamous cell carcinoma of rectum or cervix –> HPV Kaposi sarcoma –> HHV-8
What CSF findings are consistent with viral meningitis?
Normal/↑ opeing pressure
↑ lymphocytes
Normal/↑ protein
Normal glucose
