Microbiology: Virology Flashcards
What 3 DNA viruses are not linear?
Hepadnavirus (circular, incomplete), papillomavirus (circular, supercoiled), and polyomavirus (circular, supercoiled)
What properties of the PrPsc prion protein enable its infectivity?
Transmissible via infected CNS tissue (iatrogenic Creutzfeldt-Jakob disease [CJD]) or food (variant CJD); resistant to degradation by proteases & standard sterilization procedures
In which viral family do viruses have single-stranded circular RNA that is both positive sense and negative sense (ambisense)?
Arenaviruses
What hepatitis virus can initially present like serum sickness?
Hepatitis B
Where does the herpes simplex virus-2 lie latent?
Sacral ganglia
What roles do hemagglutinin and neuraminidase play with influenza infection?
Hemagglutinin promotes viral entry by binding to sialic acid; neuraminidase promotes virion release
What is the RNA structure of the deltavirus?
Enveloped, single-stranded, negative-sense, circular RNA with an uncertain capsid
Which RNA virus family does the often fatal Marburg hemorrhagic fever belong to?
Filoviruses
Name the family of each of the hepatitis viruses (HAV, HBV, HCV, HDV, HEV).
HAV - RNA picornavirus; HBV - DNA hepadnavirus; HCV - RNA flavivirus; HDV - RNA deltavirus; HEV - RNA hepevirus
What viral infections are associated with intranuclear eosinophilic Cowdry A inclusions?
Herpes simplex virus-1 (HSV-1), herpes simplex virus-2 (HSV-2), varicella-zoster virus (VZV)
What does a heterozygous CCR5 gene mutation indicate for the disease course in a patient with HIV?
Slower disease course
Name the 7 positive-stranded RNA viruses.
I go to a retro (retrovirus) toga (togavirus) party and drink flavored (flavivirus) Corona (coronavirus) and eat hippie (hepevirus) California (calicivirus) pickles (picornavirus)
Name the 4 RNA viruses that have segmented genomes.
Reovirus (10-12 segments), orthomyxovirus (8 segments), arenavirus (2 segments), and bunyavirus (3 segments)
What is the only positive-sense RNA virus with a helical capsid?
Coronaviruses
What phenomenon might be seen in a patient with severe croup?
Pulsus paradoxus caused by upper airway obstruction
Which RNA virus family does Ebola hemorrhagic fever belong to?
Filoviruses
What is the test of choice for skin and genital findings suggestive of herpes simplex virus?
Viral culture
What condition in humans is caused by picornaviruses (except rhinovirus and hepatitis A)?
Aseptic meningitis
Infections with which organisms are possible when the CD4+ count is <200 cells/mm3?
JC virus reactivation, Pneumocystis jirovecii, HIV infection leading to dementia, and Histoplasma capsulatum
How can hepatitis C be acquired?
Intravenous drug use or blood transfusions
What mediates the granular eosinophilic “ground glass” appearance found on a liver biopsy specimen of hepatitis B?
Cytotoxic T-cell damage causes the granular eosinophilic appearance
What is the DNA structure of the hepatitis B virus?
Enveloped, partially double-stranded, circular DNA
Palivizumab is used to prevent respiratory syncytial virus (RSV) in what age group?
Premature infants (Palivizumab for Paramyxovirus [RSV] Prophylaxis in Preemies)
What vaccine has made mumps uncommon?
MMR (measles, mumps, rubella)
What is the function of the 2 envelope proteins on the surface of HIV
Gp120 helps HIV adhere to CD4+ T cells; gp41 facilitates HIV fusion/entry
What is the viral receptor for rabies?
Nicotinic acetylcholine receptor
What RNA family contains the hepatitis E virus?
Hepevirus
What is the definition of viral genetic recombination?
Gene exchange between 2 chromosomes via crossing over that occurs within regions of significant base sequence homology
Which naked (nonenveloped) viruses are DNA viruses?
Papillomavirus, Adenovirus, Parvovirus, Polyomavirus (PAPP)
In what parts of the world is hepatitis E infection most common?
Asia, Africa, and the Middle East
Which populations are at particularly high risk for rotavirus?
Infants and young children, especially in day care centers and kindergartens
Name the 6 negative-stranded viral families.
Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthomyxoviruses, Filoviruses, Rhabdoviruses (Always Bring Polymerase Or Fail Replication)
Which hepatitis serologic markers are found during the window period?
IgM anti-HBc and anti-HBe
Two viruses coinfect a cell. Virus A becomes partially or completely coated with virus B proteins, but progeny have type A genome and coat. What is this called?
Phenotypic mixing
What is seen on biopsy of tissues infected with cytomegalovirus?
Cells with intranuclear inclusion bodies (owl’s eye appearance)
How does HIV integrate its genome into the host DNA?
Reverse transcriptase converts HIV viral RNA to double-stranded DNA, which then integrates into host DNA
Which lobe of the brain is most commonly affected in herpes encephalitis?
Temporal lobe
What diseases are caused by paramyxoviruses?
Parainfluenza, mumps, measles, RSV, and human metapneumovirus (which causes bronchiolitis/pneumonia in infants and children)
Name 2 coreceptors HIV can use to enter immune cells?
CXCR4 (on T-cells for late infection) and CCR5 (on macrophages for early infection)
Name 6 viral families that are single-stranded, positive-sense, linear RNA viruses with icosahedral capsids.
Picornavirus, hepevirus, calicivirus, flavivirus, togavirus, and retrovirus (HTLV only)
By way of what surface marker does Epstein-Barr virus (human herpes virus-4) infect B cells?
CD21 (“must be 21 to drink Beer in a Barr”)
What is the purpose of neuraminidase on the parainfluenza viral membrane?
Promotes progeny virion release
During which phase of HIV infection does the CD4+ cell count drop most sharply?
Acute phase (first 1–2 months)
What 2 animals act as reservoirs for the yellow fever virus?
Monkeys and humans
Viruses A and B infect a cell. A mutates and becomes nonfunctional; B makes a protein that functions for both A and B. What is this called?
Complementation
What biopsy finding is consistent with Kaposi sarcoma?
Lymphocytic inflammation (caused by human herpesvirus-8)
What presentation might cytomegalovirus infection have in the population with HIV/AIDS?
Colitis, encephalitis, pneumonitis, esophagitis, and retinitis
Why are purified nucleic acids of certain dsDNA and positive-strand ssRNA viruses infectious?
The dsDNA and ssRNA can utilize host cell machinery (eg, polymerases)
What stage of hepatitis B infection does positive anti-HBe and anti-HBc IgM indicate?
Window period
Which human papillomavirus (HPV) serotypes are associated with warts?
1, 2, 6, and 11
What are 3 general mechanisms for Zika virus transmission?
Transmitted by Aedes mosquito bites (most common), but sexual and vertical transmission are possible
Parvovirus B19 uses what receptor to attach to red blood cells?
Parvovirus B19 uses the P antigen
According to the CDC guidelines, what medical conditions are contraindications for rotavirus vaccination in infants?
History of intussusception or Severe Combined Immunodeficiency (SCID)
How is Ebola transmitted? I
Direct contact with body fluids, fomites (including corpses), infected bats/primates; nosocomial infection is common
Name 4 medically significant conditions caused by bunyaviruses.
California encephalitis, Crimean-Congo hemorrhagic fever, sandfly/Rift Valley fevers, hantavirus infection (hemorrhagic fever, pneumonia)
What is the test of choice for the diagnosis of Zika virus?
Reverse transcription polymerase chain reaction (RT-PCR) or serology
What CD4+ count is associated with esophagitis from a Candida albicans infection in patients with HIV/AIDS?
<100 cells/mm3
Which DNA virus is single stranded?
Parvovirus, the rest of the DNA viruses are all double stranded
What are the most common endocrine manifestations of hepatitis C?
↑ risk of diabetes mellitus and autoimmune hypothyroidism
In what central nervous system tissue are negri bodies commonly found in rabies infection?
Cerebellum (Purkinje cells) and/or hippocampus
What is the RNA structure of the filovirus?
Enveloped, single-stranded, negative sense, linear with a helical capsid
From what cellular structure do enveloped viruses generally get their envelopes?
From the plasma membrane as they leave the cell
How do the Epstein-Barr virus (EBV) and strep throat differ in their cervical lymphadenopathy locations?
EBV is more strongly associated with posterior cervical lymphadenopathy; strep throat involves anterior cervical lymphadenopathy
What is the prognosis for hepatitis B in adults and neonates?
Adults, mostly a full resolution; neonates, a worse prognosis
What virus causes global infantile gastroenteritis?
Rotavirus (ROTAvirus = Right Out The Anus)
What molecular characteristic allows the hepatitis C virus to outsmart host antibodies?
Lack of 3′-5′ exonuclease activity leads to antigenic variation of HCV envelope proteins and new viral mutant strains
What are the 2 most common renal manifestations of hepatitis B?
Membranous glomerulonephritis > membranoproliferative glomerulonephritis
How are the HIV envelope proteins formed?
The env gene encodes gp160 precursor that is cleaved into gp120 and gp41
What is the smallest DNA virus?
Parvovirus
What is the RNA structure of the picornavirus?
Non-enveloped, single-stranded, positive-sense, linear RNA with an icosahedral capsid
What are initial symptoms of Ebola?
Abrupt onset of flu-like symptoms, high fever, diarrhea/vomiting, myalgia
Name 2 viruses found in the reovirus family.
Rotavirus and coltivirus
What virus may be responsible for non-Hodgkin lymphoma development in patients with HIV/AIDS?
Epstein-Barr virus
What are symptoms of mumps?
Parotitis, Orchitis, aseptic Meningitis, Pancreatitis (mumps makes your parotid glands and testes as big as POM-Poms)
What type of capsid shape do most negative-sense RNA viruses have and with what exception?
Helical; delta viruses have uncertain capsid symmetry
How can hepatitis E be acquired?
Via the fecal-oral route, especially from waterborne sources
What is the RNA structure of the arenavirus?
Enveloped, single-stranded, positive- and negative-sense, circular (in 2 segments) RNA with a helical capsid
How is the chicken pox transmitted?
Via respiratory secretions or contact with fluid from vesicles
Describe the structure of the genome of most DNA viruses.
Most of them have a double stranded, linear genome
What is the function of hemagglutinin on the parainfluenza viral membrane?
Promotes viral entry by binding to sialic acid
What is the ploidy of the HIV genome?
Diploid RNA
What virus family does parainfluenza (causes croup) belong to?
Paramyxoviruses
What characteristic liver biopsy findings are seen in hepatitis C?
Lymphoid aggregates, focal macrovesicular steatosis
What is the disease that can occur with rapid-onset dementia and ataxia after eating beef from infected cattle?
Bovine spongiform encephalopathy (BSE), also known as “mad cow disease”
What is the RNA structure of the calicivirus?
Non-enveloped, single-stranded, positive-sense, linear RNA with an icosahedral capsid
Which HIV proteins are located in the envelope, matrix, and capsid, respectively?
Envelope: gp120 and gp41; matrix: p17; capsid: p24
Name the viral family that is made up of double-stranded RNA viruses with double icosahedral capsids.
Reoviruses
How does transmission for herpes simplex virus- (HSV) 1 and 2 differ?
HSV-1 is spread in respiratory secretions and saliva; HSV-2 is spread by sexual contact and perinatally
What is the route of transmission for hepatitis A?
Via fecal-oral (through ingestion of contaminated shellfish, exposure during travel, or in dayca
If the receptor intracellular adhesion molecule 1 (ICAM-1) is blocked, what virus will have difficulty infecting the cells?
Rhinovirus (binds to ICAM-1); “take a picture of the rhino with a camera”
What is the definition of moderately immunocompromised in HIV?
CD4+ count: 200-400 cells/mm3
Which of the hepatitis-causing viruses is the only DNA virus?
Hepatitis B virus (hepadnavirus)
What causes pandemics versus epidemics?
Genetic/antigenic shift causes pandemics; genetic/antigenic drift causes epidemics (sudden shift is more deadly than gradual drift)
Name some of the conditions caused by herpes simplex virus-1.
Keratoconjunctivitis, herpes labialis, herpetic whitlow, encephalitis, erythema multiforme, esophagitis, gingivostomatitis
Which 2 picornaviruses commonly cause aseptic meningitis?
Echovirus and coxsackievirus
Which DNA virus replicates outside of the nucleus?
Poxvirus; it has a DNA-dependent RNA polymerase and can replicate without nuclear enzymes
What is the RNA structure of the coronavirus?
Enveloped, single-stranded, positive-sense, linear RNA with a helical capsid
What infection in a patient who is HIV ⊕ with a CD4+ count <100 cells/mm3 presents with a TB-like disease and lymphadenitis?
Mycobacterium avium-intracellulare, Mycobacterium avium complex infection
What serologic markers would you expect in a patient immunized against Hepatitis B?
⊕ Anti-HBs (all other hepatitis B markers negative)
How is hepatitis B acquired?
Methods of acquiring HBV: Parenteral (Blood), sexual (Baby-making), perinatal (Birthing)
What disease presents with esophagitis and linear ulcerations on esophagogastroduodenoscopy (EGD) in the population with HIV/AIDS with a CD4+ count <100 cells/mm3?
Cytomegalovirus esophagitis
What dermatological conditions can be seen in patients with hepatitis C?
Sporadic porphyria cutanea tarda and lichen planus
What CD4+ count is associated with oral thrush from a Candida albicans infection in patients with HIV?
<500 cells/mm3
Where does herpes simplex virus-1 lie dormant?
Trigeminal ganglia
What is the RNA structure of the orthomyxovirus?
Enveloped, single-stranded, negative-sense, linear (in 8 segments) RNA with a helical capsid
A patient recently returned from Brazil with conjunctivitis, low-grade fever, and an itchy rash. You suspect a flavivirus to be the cause. What is the most appropriate treatment?
Supportive care (diagnosis: Zika virus infection)
Why can hepatitis D (HDV) infection only occur in conjunction with hepatitis B (HBV) infection?
HDV is a defective virus so it relies on the HBV HBsAg coat for entry into hepatocytes
What 5 RNA viruses are picornaviruses?
Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, Hepatitis A virus (PERCH on a “peak” [picornavirus])
Which 2 RNA viruses do not replicate in the cytoplasm?
Retrovirus and influenza virus (retroflu is outta cyt [sight])
Which 3 DNA virus families contain circular DNA?
Papillomaviruses, polyomaviruses, and hepadnaviruses; all other viruses have linear DNA
What rodent-borne bunyavirus causes a hemorrhagic pulmonary syndrome?
Hantavirus
How can cytomegalovirus present in adults?
Mononucleosis in immunocompetent patients; retinitis, esophagitis, and infection in immunocompromised patients (pneumonia in transplant patients)
Rhinovirus has how many serotypes?
> 100 serologic types of rhinovirus
What gene mutation can cause immunity to HIV?
Homozygous CCR5 mutation (prevents HIV binding on macrophages)
What virus family does rhinovirus belong to?
Picornavirus
What is the DNA structure of hepadnaviruses?
Enveloped, partially double-stranded, circular DNA
What findings might be seen on fundoscopic exam in a patient with vision loss due to cytomegalovirus retinitis?
Hemorrhage and cotton-wool exudates
Other than animal bites, by what method of transmission can rabies also occur?
Aerosol transmission (in bat caves)
Which naked (nonenveloped) viruses are RNA viruses?
Calicivirus, Picornavirus, Reovirus (CPR), and hepevirus
What is the DNA structure of polyomaviruses?
Non-enveloped, double-stranded, circular DNA
What serological marker is best to detect acute hepatitis A?
Immunoglobulin M hepatitis A virus antibody (anti-HAV IgM)
What test can be performed in the setting of an inconclusive differentiation assay for HIV?
HIV-1 nucleic acid test (NAT)
Which of the 2 viruses that can lead to roseola is a less common cause of the disease?
Human herpes virus-7 (HHV-7) is a less common cause than human herpes virus-6 (HHV-6)
What is the DNA structure of parvovirus?
Non-enveloped, single-stranded, linear DNA (this is the smallest of the DNA viruses)
Other than the vasculature, what other anatomic locations can Kaposi sarcoma affect?
Gastrointestinal tract and lungs
Which serologic marker indicates prior infection (or vaccination) and protects against reinfection with hepatitis A?
Immunoglobulin G anti-hepatitis A virus antibody (anti-HAV IgG)
What test can be done to confirm the diagnosis of HIV if the HIV-1/2 Ag/Ab immunoassay is positive?
HIV-1/2 antibody differentiation immunoassay (which determines whether it is HIV-1 or HIV-2 infection)
Which hepatitis types can be transmitted by blood?
Hepatitis B, C, and D
What virus family does Ebola belong to?
Filovirus
By what mechanism does rotavirus cause gastroenteritis?
Rotavirus causes destruction of the intestinal villi, thus impairing Na+ absorption and leading to K+ wasting
Two segmented viruses undergo reassortment and produce a new, highly virulent strain. What is this process called?
Antigenic shift
Which calicivirus commonly causes viral gastroenteritis?
Norovirus
What stage of hepatitis B infection does positive HBsAg, HBeAg, and anti-HBc IgM indicate?
Acute stage of infection
Which disease caused by a poxvirus has been eradicated through the use of a live attenuated vaccine?
Smallpox
What is the RNA structure of the flavivirus?
Enveloped, single-stranded, positive-sense, linear RNA with an icosahedral capsid
Which organ transplant does the BK virus commonly target?
Kidneys; BK virus = Bad Kidney virus
What is the DNA structure of herpesviruses?
Enveloped, double-stranded, linear DNA
What is the incubation period for Ebola?
Up to 21 days
A man has a common cold because of a single-stranded, linear RNA virus that has an envelope. Name other viruses in the same family.
SARS and MERS; the patient’s cold is caused by a coronavirus
What is the RNA structure of the hepatitis D virus (HDV)?
Single-stranded, negative-sense, circular RNA
What is the typical presentation of rubella (German measles) infection?
Fever; postauricular lymphadenopathy; and a fine, maculopapular rash on the face and trunk, usually lasting for 3 days (hence the term “3-day measles”)
Which viral family is responsible for smallpox, cowpox, and molluscum contagiosum?
Poxvirus
What herpesvirus can cause shingles, encephalitis, and pneumonia?
Varicella-zoster virus (HHV-3)
What is the name of the disease associated with “slapped cheeks” in children with parvovirus?
Erythema infectiosum or fifth disease
What is the DNA structure of papillomaviruses?
Non-enveloped, double-stranded, circular DNA
What viral family has the largest DNA virus?
Poxvirus
What is the RNA structure of the paramyxovirus?
Enveloped, single-stranded, negative-sense, linear (nonsegmented) RNA with a helical capsid
Infections with which organisms are possible when the CD4+ count is <100 cells/mm3?
Aspergillus fumigatus, Bartonella, Cryptococcus neoformans, Candida albicans, Cryptosporidium spp, Toxoplasma gondii, Mycobacterium avium-intracellulare, M avium complex, CMV, EBV
What is the DNA structure of poxviruses?
Enveloped, double-stranded, linear DNA (this is the largest of the DNA viruses)
What virus causes croup?
Parainfluenza virus
What is the pathophysiology of prion disease?
Normal prion protein (PrPc) converts to β-pleated sheets (PrPsc), which accumulate in the central nervous system
What vascular pathology can occur with hepatitis C?
Leukocytoclastic vasculitis
In contrast to the other picornaviruses, what type of infection does rhinovirus not cause?
Gastrointestinal tract infections; it is acid labile and destroyed by stomach acid
Name 5 medically significant conditions caused by coxsackieviruses.
Aseptic meningitis, pericarditis, herpangina (mouth blisters/fever), myocarditis, and hand/foot/mouth disease
To what viral family does hepatitis B virus belong?
Hepadnaviridae
What malignancy is associated with human papillomavirus infection in the population with HIV/AIDS?
Squamous cell carcinoma of the anus or cervix
Name the 7 DNA viruses.
Hepadnavirus, Herpesvirus, Adenovirus, Poxvirus, Parvovirus, Papillomavirus, and Polyomavirus (HHAPPPPy viruses)
Name 6 medically significant conditions caused by flaviviruses.
Hepatitis C, yellow fever, St. Louis encephalitis, Zika virus infection, West Nile disease (meningoencephalitis, flaccid paralysis), and dengue
How can cytomegalovirus be transmitted?
Via sexual contact, transfusion, urine, saliva, organ transplants, and congenitally
Chronic hepatitis B can have what hematologic abnormality?
Pancytopenia secondary to aplastic anemia
Which 2 viruses in the picornavirus family are not enteroviruses?
Rhinovirus and HAV
Which types of hepatitis can have a carrier state?
Hepatitis B, C, and D
What prion disease is notable in tribal populations practicing human cannibalism?
Kuru
What is the Tzanck test?
A smear of an open vesicle used to detect multinucleated giant cells seen in herpes simplex virus (HSV) infections (HSV-1, HSV-2, VZV; Tzanck heavens I do not have herpes)
Rhinovirus causes what type of infection in humans?
The common cold (rhino has a runny nose)
What complication may occur to a fetus exposed to parvovirus B19?
Hydrops fetalis (due to RBC destruction) and possibly death
What are the viral receptors for HIV?
CD4, CXCR4, and CCR5
What signs and symptoms are characteristic of all hepatitis viruses?
Fever, jaundice, and elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST)
What is the treatment of choice for Ebola?
There is no definitive treatment; supportive care, strict isolation, barrier practices for health care workers
What are the 4 stages of untreated HIV infection?
- Flu-like, acute; 2. Feeling fine, latency; 3. Falling count, constitutional; 4. Final crisis, opportunistic infections (the Four stages)
What hepatitis virus is associated with polyarteritis nodosa?
Hepatitis B
Which RNA viral family do the measles and mumps viruses belong to?
Paramyxoviruses
What is the test of choice for determining maternal HIV transmission to a newborn child?
HIV viral load in the newborn
What stage of hepatitis B infection does positive HBsAg, anti-HBe, and anti-HBc IgG indicate?
Chronic HBV (low infectivity)
In patients with HIV, what virus can cause progressive multifocal leukoencephalopathy (PML)?
JC (Junky Cerebrum) virus
What is the difference between immunoglobulin M (IgM) versus immunoglobulin G (IgG) hepatitis B core antibodies?
IgM is a marker for acute or recent disease; IgG is a marker for prior exposure or chronic infection
What is the RNA structure of the hepevirus?
Non-enveloped, single-stranded, positive-sense, linear RNA with an icosahedral capsid
What 3 virus families have circular RNA structures?
Arenaviruses, bunyaviruses, and delta viruses
What are the criteria for the diagnosis of acquired immunodeficiency syndrome (AIDS)?
CD4+ count ≤200 cells/mm3, HIV ⊕ with AIDS-defining illness, or CD4+ <14%
What viral strains are found in the flu shot?
Viral strains that are most likely to appear during a flu season (due to the virus’ rapid genetic change); it is a reformulated vaccine
Which RNA virus causes croup?
Parainfluenza
How does the monospot test work?
Detects heterophile antibodies by the agglutination of sheep or horse red blood cells
What are the viral receptors for CMV?
Integrins (heparan sulfate)
What patient population has a high mortality rate if infected with hepatitis E virus?
Pregnant women (HEV: Enteric, Expectant mothers, Epidemic)
An outdoorsman presents to the emergency department with a high fever, black-colored vomitus, and jaundice. How is the likely causative organism transmitted?
Via the Aedes mosquito (diagnosis: yellow fever)
In what patient population do you typically see Epstein-Barr virus infection?
Teenagers and young adults
What is the mechanism by which rabies causes infection?
Binds to acetylcholine receptors and migrates retrogradely up the axon via dynein motor proteins to the CNS
What is the name for the dark, violaceous plaques/nodules resembling vascular proliferation caused by human-herpes virus 8?
Kaposi sarcoma
What infection in patients with HIV/AIDS presents with cough, fever, and dyspnea with CD4+ count <200 cells/mm3, and the chest x-ray shows bilateral ground-glass opacities?
Pneumocystis jirovecii pneumonia
The Centers for Disease Control no longer recommends what confirmatory testing for HIV?
Western blots
What biopsy findings are associated with a Histoplasma capsulatam infection in patients with HIV/AIDS?
Macrophages contain oval yeast cells (presents with fever, fatigue, weight loss, cough, nausea, vomiting, dyspnea, and diarrhea)
In what age group do diseases caused by paramyxoviruses predominate?
Infants and children
Which diseases are caused by arboviruses (RNA viruses transmitted by arthropods)?
Colorado tick, Yellow, dengue, Zika, St. Louis/Eastern/Western equine/California encephalitis, Crimean-Congo, West Nile, Chikungunya, Sandfly/Rift Valley
What 2 vaccines can be used for poliovirus infections?
Salk (IPV) and Sabin (OPV)
What clinical manifestations does prion PrPsc accumulation cause?
Spongiform encephalopathy, ataxia, dementia, death
How is Ebola diagnosed?
Perform reverse transcription polymerase chain reaction (RT-PCR) within 48 hours of symptom onset
Which animal bites are most likely to result in rabies infection in the United States?
Bat, raccoon, skunk bites (all more common causes of rabies than dog bites)
Which DNA virus is not icosahedral in shape?
Poxvirus (it is complex)
How does cytomegalovirus infection present on fundoscopy?
Cotton-wool spots
Name the 2 RNA viruses that are retroviruses.
Human immunodeficiency virus (HIV) and human T-lymphotropic virus (HTLV)
Which herpesvirus is the most common cause of sporadic encephalitis?
Herpes simplex virus-1
What RNA virus family does rabies belong to?
Rhabdoviruses
Which viral family includes the hepatitis D virus?
Delta viruses
Which cells do filoviruses target?
Endothelial cells, phagocytes, and hepatocytes
Which well-known RNA virus family has reverse transcriptase?
Retrovirus
In 2009, the H1N1 influenza A pandemic was caused by a complex viral genetic event. What was the event?
Reassortment (viruses with segmented genomes exchange segments); in this case, complex reassortments among human, swine, and avian viruses
Which hepatitis viruses do not have carrier states?
Hepatitis A and E
If you test for HIV-1 antibodies and receive an indeterminate result, which test can you subsequently order to better assess the patient’s HIV status?
An HIV-1 nucleic acid test (NAT)
To what common sterilization procedure are prion diseases known to be resistant?
Standard autoclaving
A patient has fever, black emesis, and scleral icterus. Liver biopsy reveals Councilman bodies (eosinophilic apoptotic globules). To which viral family does the virus belong?
Flavivirus; diagnosis: yellow fever virus, which is also an arbovirus (Flavi means yellow or jaundiced)
What is the RNA structure of the rhabdovirus?
Enveloped, single-stranded, negative-sense, linear RNA with a helical capsid
Which virus in the reovirus family causes fatal diarrhea in children?
Rotavirus
Describe the structure of all herpesviruses.
Enveloped, double-stranded, and linear DNA viruses
What is the mechanism for how parvovirus causes erythema infectiosum?
By infecting RBC precursors and endothelial cells
How do you evaluate response to antiretroviral therapy for HIV?
Test the amount of viral RNA in plasma; higher viral loads indicate a poorer prognosis
Coltivirus is the causative agent for which illness?
COLTIvirus causes COLorado TIck fever
At what CD4+ count are acquired immunodeficiency syndrome- (AIDS) defining illnesses expected to emerge in HIV?
<200 cells/mm3
What picornavirus causes the “common cold?”
Rhinovirus
What cells are affected in Kaposi sarcoma?
It is a neoplasm of the endothelial cells of the vasculature
What hematologic manifestations can occur in hepatitis C infection?
Essential mixed cryoglobulinemia, B-cell non-Hodgkin lymphoma, idiopathic thrombocytopenic purpura, and autoimmune hemolytic anemia
How does cytomegalovirus (CMV, HHV-5) establish latency?
CMV establishes latency in mononuclear cells
Describe the progression of rabies infection.
Fever and malaise leading to agitation, photophobia, hydrophobia, hypersalivation, then paralysis, coma, and death
What fatal bacterial infections can occur after influenza?
Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae
Name 8 naked (nonenveloped) viruses.
Parvovirus, Adenovirus, Papillomavirus, Polyomavirus, Calicivirus, Picornavirus, Reovirus, and Hepevirus (give PAPP smears and CPR to a naked hippie)
How many RNA segments do Bunyaviruses, Orthomyxoviruses, Arenaviruses, and Reoviruses each have, respectively?
3, 8, 2, and 10-12 (BOARding flight 382 in 10-12 minutes)
Name 5 medically significant members of the picornavirus family.
Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV (PERCH)
What is the RNA structure of the bunyavirus?
Enveloped, single-stranded, negative-sense, circular (in 3 segments) RNA with a helical capsid
Individuals with HIV are at high risk for what types of cancers when infected with the Epstein-Barr virus?
Non-Hodgkin lymphoma, CNS lymphoma
If the receptor CD21 is blocked, what virus will have difficulty infecting the cells?
Epstein-Barr virus (EBV)
Which herpesviruses are transmitted in respiratory secretions versus via sexual contact?
HSV-1, Epstein-Barr virus, and varicella-zoster virus are transmitted in respiratory secretions; HSV-2, cytomegalovirus, and HHV-8 are transmitted by sexual contact
How are HIV envelope proteins acquired?
Acquired via budding from the host cell plasma membrane
Compare the incubation periods of hepatitis A, B, C, and E.
Hepatitis A and E: short (weeks); B and C: long (months)
What is the role of the surface F (fusion) protein that is common to all paramyxoviruses?
Causes respiratory epithelial cells to fuse and become multinucleated
What superinfection could worsen the prognosis of active hepatitis B infection?
A superinfection with hepatitis D virus
What are severe complications of Ebola?
DIC (diffuse intravascular coagulation), diffuse hemorrhage, shock, death (high mortality rate)
Where does HIV replicate during the latent phase?
Lymph nodes
Describe the structure of orthomyxoviruses.
Enveloped, negative-sense, single-stranded RNA viruses with 8 segments
Why do negative-stranded RNA viruses carry RNA-dependent RNA polymerase?
To transcribe the negative strand to a positive strand in the host cell in order to replicate
What are possible central nervous system sequelae of measles?
Subacute sclerosing panencephalitis (years later) and encephalitis (1:2000 cases)
In phenotypic mixing, how is the tropism (infectivity) of a progeny virus determined?
By which parent virus passes along its coat to the progeny virus
What is the most common cause of measles-associated death in children?
Pneumonia
What prion disease causes sporadic, rapidly progressive dementia?
Creutzfeldt-Jakob disease
Describe the common skin findings associated with molluscum contagiosum.
Flesh-colored papules with central umbilication
What disease does respiratory syncytial virus (RSV) cause in babies?
Bronchiolitis
What is the RNA structure of the retrovirus?
Enveloped, single-stranded, positive-sense, linear (2 copies) RNA with either an icosahedral capsid (HTLV) or a complex, conical capsid (HIV)
What is a patient’s HIV status if the nucleic acid test (NAT) is negative but HIV Ag/Ab immunoassay is positive?
HIV ⊖, as the HIV Ag/Ab immunoassay was likely a false positive
What virus can act like Epstein-Barr virus (EBV) but have a negative monospot test?
Cytomegalovirus (human herpesvirus type-5)
In viral genetics, what is the definition of reassortment?
The exchange of genetic material among viruses with segmented genomes (eg, the influenza virus)
What DNA virus in adults can cause pure RBC aplasia and rheumatoid arthritis-like symptoms?
Parvovirus B19
What human papillomavirus (HPV) serotypes are most commonly associated with cervical cancer?
16 and 18
What is the incubation period before symptom onset in rabies?
Weeks to months
What is the source of the HBeAg found in the serum of a patient infected with hepatitis B?
Secretion by infected hepatocytes into the circulation; it is not part of the mature HBV virion
What should be done for postexposure prophylaxis in rabies?
Clean the wound and administer killed rabies vaccine and rabies immune globulin (passive-active immunity)
Coronaviruses are the causative agents of what 3 diseases?
Common cold, Middle East respiratory syndrome (MERS), and severe acute respiratory syndrome (SARS)
What antigen is associated with the core of hepatitis B virus?
HBcAg
What common diseases are possible in the population with HIV/AIDS when the CD4+ count is <500 cells/mm3?
Candida albicans oral thrush, Epstein-Barr virus oral leukoplakia, human herpesvirus-8 Kaposi sarcoma, and human papillomavirus squamous cell carcinoma
During which phase of HIV infection does the CD8+ T-cell count decline the most rapidly?
Systemic immunodeficiency/AIDS-defining illnesses phase
Why are naked nucleic acids of negative-strand ssRNA and dsRNA viruses not infectious?
They require polymerases found in the complete virion to become infectious
What is the mechanism of action of palivizumab?
Monoclonal antibody against the surface F protein of RSV (respiratory syncytial virus)
What infection in patients with HIV/AIDS presents with pleuritic chest pain, hemoptysis, and a CD4+ count <100 cells/mm3?
Aspergillus fumigatus
Which RNA virus family does the influenza virus belong to?
Orthomyxoviruses
How are human herpes-viruses 6 and 7 transmitted?
Saliva
Name the proteins for which each of these HIV genes code: env, gag, pol.
env: gp120 and gp41; gag: p24 and p17; pol: Reverse transcriptase, Integrase, Protease (RIP “Pol” [Paul])
What type of infections might be seen with HIV when the CD4+ count is 200-400 cells/mm3?
Skin and mucous membrane infections
Purified nucleic acids from which 2 dsDNA viruses are not considered infectious?
Poxvirus and hepatitis B virus (they require nonhuman enzymes for replication)
What disease in patients with HIV/AIDS presents with neurological dysfunction (eg, gait and cognitive impairment) and a brain MRI that shows nonenhancing areas of demyelination?
Progressive multifocal leukoencephalopathy (due to JC virus reactivation); CD4+ count <200 cells/mm3
What is the RNA structure of the reovirus?
Non-enveloped, double-stranded, linear RNA in 10-12 segments with a double icosahedral capsid
Which 2 diseases are caused by arenaviruses?
Lymphocytic choriomeningitis (from LCMV) and Lassa fever encephalitis (spread by rodents)
What viruses are part of the Togavirus family?
Toga CREW - Chikungunya virus, Rubella, Eastern and Western equine encephalitis
What herpesvirus is the most common cause of mononucleosis?
Epstein-Barr virus (human herpesvirus-4)
Name 4 medically important paramyxoviruses.
Parainfluenza virus, Respiratory syncytial virus, Mumps, and Measles (PaRaMyxovirus)
Describe the lymph node biopsy findings of a patient with measles.
Warthin-Finkeldey giant cells (fused lymphocytes) present in a background of paracortical hyperplasia
Compare the incubation periods of hepatitis D (HDV) with hepatitis B (HBV) superinfection versus HBV coinfection.
D: short when superinfection (HDV after HBV), long when coinfection (HDV with HBV)
The HIV RNA levels peak during which phases of infection?
Acute infection phase and systemic immunodeficiency/AIDS-defining illnesses phase
A recent South American emigrant gives birth to an infant with microcephaly. You suspect a viral infection as the cause. What is the most likely diagnosis?
Zika virus, transmitted by the mother to the fetus during development
Why are the hepatitis B, C, and D viruses unable to spread via the fecal-oral route?
Unlike naked viruses (eg, HAV and HEV: the vowels hit your bowels), enveloped viruses are killed in the gut
What CD4+ count is associated with Toxoplasma gondii infection?
<100 cells/mm3
Which hepatitis virus is most likely to progress to cirrhosis or carcinoma?
Hepatitis C; most likely to progress to Cirrhosis or Carcinoma
All segmented viruses have what type of viral genome?
RNA
Describe the symptoms/signs of serum sickness.
Fever, arthralgias, rash; can represent initial infection with hepatitis B
What is the function of the hepatitis B DNA polymerase?
Completes partial double-stranded DNA upon viral entry and reverse transcribes viral RNA to DNA for progeny genome synthesis
What cancers are associated with Ebstein-Barr virus?
Lymphomas (endemic Burkitt), lymphoproliferative disease in transplant patients, and nasopharyngeal carcinoma
What disease process should you consider in the population with HIV/AIDS with CD4+ count <200 cells/mm3, progressive memory loss, and an otherwise negative infectious work-up?
HIV dementia
How is the reovirus genome unique among RNA viruses?
It has double-stranded RNA; all other RNA viruses are single stranded
The genome of virus A is coated with surface proteins from virus B. Whose genetic material will the subsequent progeny of this newly formed virus have?
The progeny will have virus A genetic material with virus A coating; this is phenotypic mixing
Which antibody is protective against hepatitis B infection acquired after recovery from an infection or vaccination?
Hepatitis B surface antibody (anti-HBs)
What viral infection is associated with aplastic crises in sickle cell disease?
Parvovirus B19
Once picornavirus RNA has entered the cell, what processing steps yield functional viral proteins?
The RNA is translated into a single polypeptide, which is then cleaved by virus-encoded proteases into functional viral proteins
What stage of hepatitis B infection does positive anti-HBs, anti-HBe, and anti-HBc IgG indicate?
Recovery stage
What is the difference between testing positive for HBeAg versus anti-HBe in terms of transmissibility?
HBeAg indicates active viral replication (high transmissibility); anti-HBe indicates low transmissibility
How does CNS lymphoma differ from a Toxoplasma gondii infection on a brain MRI of a patient who is HIV ⊕?
A solitary ring-enhancing lesion is usually seen in CNS lymphoma; multiple lesions are usually found in a Toxoplasma gondii infection
How do intramuscular and intranasal flu vaccines differ?
Injection contains killed virus; nasal spray has live mutant virus that is temperature sensitive and replicates in the nose (not the lungs)
What virus can cause conjunctivitis, myocarditis, and febrile pharyngitis and has double-stranded and linear DNA?
Adenovirus
Why are contact sports avoided in patients with mononucleosis?
Risk of splenic rupture
What is the pathophysiology of the “blueberry muffin” rash seen in congenital rubella?
Dermal extramedullary hematopoiesis
What are the tests of choice for cryptococcal meningitis infection?
India ink stain to reveal yeast with a large capsule, or test directly for the capsular antigen
What is a pseudovirion?
The genetic material of one virus coated by the surface proteins of a different virus
Structurally, what type of virus is a picornavirus?
A small RNA virus (picoRNAvirus = small RNA virus)
How are arboviruses transmitted?
By arthropods (mosquitoes, ticks) (arbovirus, arthropod borne)
What would you see on the liver biopsy of a patient infected with hepatitis A?
Hepatocyte swelling, Councilman bodies, and monocyte infiltration
Use of what antibiotic in mononucleosis can cause a characteristic maculopapular rash?
Amoxicillin (prescribed for presumed streptococcal pharyngitis when diagnosis is actually mononucleosis)
What is the RNA structure of the togavirus?
Enveloped, single-stranded, positive-sense, linear RNA with an icosahedral capsid
What is the capsid symmetry of the hepatitis D virus (a delta virus)?
Uncertain (recall that hepatitis D is a “defective” virus that requires HBV co-infection)
Hepatitis D virus (HDV) infection needs coinfection with hepatitis B to supply the envelope protein for HDV. What is this called?
Complementation
What sequelae of infection can occur after measles in an immunocompromised patient?
Giant cell pneumonia, occurs mostly in the immunosuppressed
What is expected on a biopsy of bacillary angiomatosis in a patient who is HIV ⊕?
Neutrophilic inflammation caused by Bartonella spp
What condition is caused by West Nile virus?
Meningoencephalitis
What is the test of choice for herpes simplex virus (HSV) encephalitis?
HSV polymerase chain reaction (PCR) of the cerebrospinal fluid (CSF)
Structurally, what are the 4 main classes of viruses?
Naked viruses with icosahedral capsids, enveloped viruses with icosahedral capsids, enveloped viruses with helical capsids, and bacteriophages
Which family of RNA viruses is NOT single-stranded RNA?
The Reoviridae family; all are single-stranded RNA except “repeatovirus” (reovirus), which is double-stranded RNA
What are the 4 Cs of measles?
Cough, Coryza, Conjunctivitis, and “C”oplik (Koplik) spots
Which family of DNA viruses does not contain double-stranded DNA?
Parvoviridae, which has single-stranded DNA (Parvovirus is part-of-a-virus)
What type of viral genomic structure is necessary for viral genome reassortment?
A segmented genome
What does a positive test for hepatitis B surface antigen indicate?
Active hepatitis B infection
What endoscopic and biopsy findings are seen in Candida albicans esophagitis?
White plaques on endoscopy; biopsy shows yeast and pseudohyphae
Rubella is part of which prenatal screening panel?
ToRCHeS infection
What stage of hepatitis B infection does positive HBsAg, HBeAg, and anti-HBc IgG indicate?
Chronic HBV (high infectivity)
Name the 2 major antigens of the influenza virus.
Hemagglutinin and neuraminidase
For which hepatitis virus is a chronic carrier state common?
Carrier states are very common with HCV
Retroviruses and the hepatitis B virus have what enzyme in common?
Reverse transcriptase
Describe the shape of the rabies virus.
Bullet-shaped
How does the rash caused by roseola infantum spread?
Starts on the trunk and then spreads to extremities
What do IgG antibodies to HBcAg signify?
Chronic infection or prior exposure to hepatitis B
Which herpes simplex virus is more likely to cause viral meningitis?
Herpes simplex virus-2 (HSV-2)
What is a patient who is HIV ⊕ generally at risk for as the CD4+ cell count drops?
Reactivation of past infections (eg, TB, shingles, HSV), non-Hodgkin lymphoma, dissemination of bacterial/fungal infections
How might a patient infected with hepatitis A virus typically present?
Asymptomatic and Acute (HAV)
What infection in HIV presents with white patches on the lateral side of the tongue that cannot be scraped off?
Oral hairy leukoplakia (due to Epstein-Barr virus)
What does the HIV-1/2 Ag/Ab immunoassay detect for in serum?
Viral p24 capsid protein antigen and IgG antibodies to HIV-1/2
What is the viral structure and family of a rotavirus?
It is a segmented, double-stranded RNA virus in the reovirus family
After a positive nucleic acid test (NAT) for HIV, which test do you use to determine appropriate antiretroviral therapy?
HIV genotype testing
Where does human herpes virus-3 lie latent?
In the dorsal roots or trigeminal ganglia
What is the test of choice for cryptosporidium infection in patients with HIV/AIDS?
An acid-fast stain of the stool sample, showing acid-fast oocysts in the stool (presents clinically with chronic watery infections)
From what cellular structure in their hosts do the herpesviruses acquire their envelopes?
Nuclear Membrane
What does the human immunodeficiency virus do during the acute phase of infection?
Widespread dissemination and seeding of the lymphoid organs
Name the 4 families of RNA viruses that have no envelope.
Reoviruses, picornaviruses, hepeviruses, and caliciviruses
What DNA virus is associated with “milkmaid blisters?”
Cowpox
What possible sequelae can occur in mumps, especially after puberty?
Sterility, particularly when it affects boys after puberty
Why is HIV-1/2 antigen/antibody testing not recommended in babies with suspected HIV?
Due to maternally transferred HIV antibodies; need to check the viral load to determine the status
Name 4 segmented RNA viruses.
Bunyaviruses, Orthomyxoviruses (influenza), Arenaviruses, Reoviruses (BOAR)
What is the DNA structure of adenoviruses?
Non-enveloped, double-stranded, linear DNA
Does a patient with a CD4+ count of 150 cells/mm3 with no history of acquired immunodeficiency syndrome- (AIDS) defining illnesses have AIDS?
Yes, because the patient’s CD4+ count is <200 cells/mm3
Cranial nerve V1 involvement of varicella-zoster virus can cause what disease?
Herpes zoster ophthalmicus
