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Virology Flashcards

1
Q

phenotypic mixing

A

Simultaneous infection of a cell with 2 viruses

Genome of virion A can be partially or completely coated forming a pseudovirion with the surface proteins of virus B

Type B protein coat determines the tropism (infectivity) of the hybrid virus

Progeny have a type A coat that is encoded by its type a A genetic material

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2
Q

All RNA viruses have ssRNA genomes except

A

Reoviridae (dsRNA)

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3
Q

+ssRNA

A 
Retrovirus
Togavirus
Flavivirus
Coronavirus
Hepevirus
Calicivirus
Picornavirus

“I went to a retro Toga party where I drank flavored Corona and ate hippie Cali pickles”

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4
Q

(-) vs (+) strand

A

mostly : (+) strand purified nucleic acids are infectious

but (-) strand are not and require polymerase contained in the complete virion. Virion brings its own RNA dependent RNA polymerase

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5
Q

Nonenveloped/naked viruses

A

“give PAPP smears and CPR to a naked hippie”

Papillomavirus
Adenovirus
Parvovirus
Polyomavirus
Calicivirus
Picornavirus
Reovirus
Hepevirus
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6
Q

DNA viruses

A

they are HHAPPPPy viruses

Hepadna –> HBV, not retrovirus, has reverse transcriptase

Herpes

Adeno –> febrile pharyngitis, pink eye, etc

Pox –> molluscum contagiosum

Parvo –> B19 virus causing a slapped cheek rash in children. RBC destruction in fetus –> hydrops fetalis. Aplastic crisis and RA sx

Papilloma –> warts are 6,11. Cervical cancer are 16 and 18

Polyoma –> JC virus causes progressive multifocal leukoencephalopathy (PML) in HIV. BK virus transplant patients commonly targets kidneys

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7
Q

All DNA viruses are double stranded except

A

Parvo

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8
Q

All DNA viruses replicate in the nucleus except

A

Poxvirus

“Pox is out of the box (nucleus)

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9
Q

HSV1

A

Keratoconjunctivitis and herpes labialis
Herpetic whitlow on finger
Temporal lobe encephalitis (most common cause of sporadic encephalitis)

Trigeminal ganglia

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10
Q

HSV2

A

Herpes genitalis and neonatal herpes

Sacral ganglia

Viral meningitis more common compared to HSV1

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11
Q

HSV3

A

Spread via resp secretions

Varicella zoster

Most common cause of shingles is post herpetic neuralgia

Latent in dorsal root or trigeminal ganglia. If CN V1 is involved then it can cause herpes zoster ophthalmicus

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12
Q

EBV or HHV-4

A

Epstein Barr Virus (HHV-4) - infects B cells through CD21. Atypical lymphocytes on peripheral blood smear (due o cytotoxic T cells)

“kissing disease” or mononucleosis - fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (esp posterior lymph nodes)

AVOID contact sports due to risk of splenic rupture

Associated with Burkitt lymphoma, nasopharyngeal carcinoma, lymphoproliferative diseases in transplant pt

+monospot test - heterophile antibodies detected by agglutination of sheep or horse RBCs

Amoxicillin causes characterisitc maculopapular rash

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13
Q

Cytomegalovirus (HHV-5)

A

(-) monospot test in immunocompetent pt

pneumonia in transplant pts
AIDS retinitis “sightomegalovirus”: hemorrhage, cottom-wool exudates, vision loss

“owl eye” intranuclear inclusions

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14
Q

HHV 6 and 7

A

spread via saliva. Fever first, rosy rash later

Roseola infantum (exanthem subitum): high fever for several days that can cause seizures followed by a diffuse macular rash.

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15
Q

HHV 8

A

Sexual contact

Kaposi sarcoma (neoplasm of endothelial cells) in HIV/AIDS p and transplant pt

dark/violaceous plaques or nodules representing vascular proliferation

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16
Q

Tzanck test

A

a smear of an opened skin vesicle to detect multinucleated giant cells commonly seen in HSV 1, HSV2, VZV . Can also see intranuclear eosinophilic cowdry A inclusions

“Tzanck heavens I do not have herpes”

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17
Q

Receptors used by viruses

CMV
EBV
HIV
Parvovirus B19
Rabies
Rhinovirus
A 
CMV - integrins (heparan sulfate)
EBV- CD21
HIV - CD4,CXCR4, CCR5
Parvovirus B19 - P antigens on RBCs
Rabies- Nicotinic AChR
Rhinovirus- ICAM-1
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18
Q

(-) RNA

A

Always Bring Polymerase Or Fail Replication

Arenavirus
Bunyavirus
Paramyxovirus
Orthomyxovirus
Filovirus
Rhabdovirus
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19
Q

Segmented virus

A

BOAR

Bunyavirus
Orthomyxovirus (influenza virus)
Arenavirus
Reovirus

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20
Q

Picornavirus

A

Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV

1 large polypeptide that is cleaved by proteases into function viral proteins

aseptic viral meningitis and enteroviruses (except Rhino and HAV)

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21
Q

Rhinovirus

A

A Picornavirus
Common cold
Acid labile - destroyed in stomach acid –> cant infect GI

22
Q

Pt presents with high fever, black vomit, and jaundice

A

Yellow fever virus (a flavivirus)

Aedes mosquitoes

councilman bodies (eosinophilic apoptotic globules) on liver biopsy

23
Q

Rotavirus

A

dsRNA virus (reovirus)

Most important global cause of infantile gastroenteritis

villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+

vaccinate all children except SCID pt

24
Q

Influenzavirus

A

Orthomyxoviruses

eight segment genome

Contains hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens

pt at risk for super infection via S aureus, S pneumo, and H influenzae

Genetic/antigenic shift causes pandemics
Genetic/antigenic drift causes epidemics

25
Q

Rubella virus

A

Togavirus

Fever, postauricular and other lymphadenopathy, arthralgias, and fine maculopapular rash that starts on face and spreads centrifugally to involve trunk and extremities

Serious congenital disease - “blueberry” muffin appearance due to dermal extramedullary hematopoiesis

26
Q

Paramyxoviruses

A

Cause disease in children

Surface (F) protein which causes respiratory epithelial cells to fuse and form multinucleated cells

give Palivizumab (monoclonal Ab against F protein) as prophylaxis to premature infants

27
Q

Croup or acute laryngotracheobronchitis

A

Parainfluenza virus (paramyxovirus)

Hemagglutinin which binds sialic acid and promotes viral entry and neuraminidase (promotes progeny virion release) antigens

“seal like” barking cough and inspiratory stridor
Steeple sign on xray - narrowing of uppe trachea and subglottis
Severe croup –> pulsus paradoxus secondary to upper airway obstruction

28
Q

Measles virus

A

Rubeola (paramyxovirus)

prodromal fever with cough, coryza, and conjunctivitis

Koplik spots - bright red spots with blue-white center on buccal mucosa. Followed by a maculopapular rash that starts at the head/neck and spreads downward

lymphadenitis with warthin-finkeldey giant cells (fused lymphocytes) in background of paracortical hyperplasia

29
Q

Mumps virus

A

Parotitis (inflammation of parotid glands)
Orchitis (inflammation of testes)
Aseptic meningitis
Pancreatitis

30
Q

Rabies Virus

A

bullet shaped virus

Negri bodies (cytoplasmic inclusions) commonly in purkinje cells of cerebellum and hippocampal neurons

Travels to the CNS by migrating in retrograde fashion (via dynein motors) up nerve axons after binding to ACh receptors

31
Q

Ebola virus

A

Filovirus

targets endothelial cells, phagocytes, hepatocytes

diarrhea, vomiting, high fever, myalgia, progression to DIC, difuse hemorrhage, shock

dx with RT-PCR 48 hrs after sx onset

32
Q

Zika virus

A

Flavivirus

Aedes mosquito

conjuntivitis, low grade pyrexia, and itchy rash

congenital microcephaly

33
Q

HAV liver biopsy

A

Hepatocyte swelling

Monocyte infiltration

Councilman bodies

34
Q

HBV liver biopsy

A

Granular eosinophilic “ground glass” appearance

Cytotoxic T cells mediate damage

35
Q

HCV liver biopsy

A

Lymphoid aggregates with focal areas of macrovesicular steatosis

36
Q

HDV

A

Super infection (HDV after HBV) = short

coinfection (HDV with HBV) = long

Defective virus because it depends on HBV HBsAg coat for entry into hepatocytes

37
Q

HEV

A

Fecale-oral, especially water borne

fulminant hepatitis in Expectant (pregnant) women

High mortality in pregnant women

Liver biopsy shows patchy necrosis

38
Q

Anti-HAV (IgM)

Anti-HAV (IgG)

A

acute hep A

prior HAV infection/vacccination –> prevents reinfection

39
Q

HBsAg

A

Antigen of HBV

Hep B infection

40
Q

Anti HBs

A

antibody to HBsAg

immunity due to past Hep B or vaccination

41
Q

HBcAg

A

Antigen associaed with core of HBV

42
Q

Anti-HBc

A

Antibody to HBcAg

IgM = acute/recent
IgG= prior or chronic infection
43
Q

HBeAg

A

secreted by infected hepatocyte into circulation

active viral replication

44
Q

Anti HBe

A

antibody to HBeAg

45
Q

HIV

A

Diploid genome ( 2 molecules of RNA)

env (gp120 and gp41) - gp120 attaches to host CD4+ and gp41 is for fusion and entry

gag (p24 and p17) - p24 is capsid and p17 is a matrix protein

pol - reverse transcriptase, aspartate protease, integrase

Virus binds CD4 and either CCR5 on macrophages in early infection or CXCR4 on T cells in late infection

homozygous CCR5 mutation = immunity
heterozygous CCR5 mutation = slower coarse

46
Q

HIV dx

A

AIDS dx when < or equal to 200 CD4 cells

first do a HIV1/2 Ag/Ab immunoassay which detecs viral p24 capsid protein and IgG abs to HIV 1/2

Confirm with HIV 1/2 ab differentiation immunoassay which tells you if its HIV 1/2

Inconclusive? nuclec acid amplification test (NAAT). If negaive then it was a false positive inititally

47
Q

Prions (not a virus)

A

conversion of a normal alpha prion protein (PrP^c) to a beta pleated form (PRP^sc) which is transmissible via CNS related tissue or food contaminated by BSE infected animal products

PRP^sc resists protease degradation and facilitates teh conversion of still more PrP^c to PrP^sc

ultimately results in spongiform encephalopathy and dementia, ataxia, and death

48
Q

Creutzfeldt-Jakob disease

A

prion disease

rapidly progressive dementia
sporadic

49
Q

Bovine spongiform encephalopathy

A

mad cow disease

50
Q

Kuru

A

acquired prion disease

tribal populations

human cannibalism

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