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USMLE1 - Microbiology > 4. Viruses > Flashcards

4. Viruses Flashcards

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1
Q

Naked Icosahedral virus

A
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2
Q

Enveloped Icosahedral virus

A
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3
Q

Enveloped helical virus

A
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4
Q

Recombination

A

Exchange of genes btw 2 Chromosomes by crossing over w/in regions of significant base sequence homolgy.

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5
Q

Reassortment

A

When viruses w/ segmented genomes (e.g., influenza virus) exchange segments. High-frequency recombination. Cause of worldwide influenza pandemics.

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6
Q

Complementation

A

When 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein. The nonmutated virus complements the mutated one by making functional protein that serves both viruses.

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7
Q

Phenotypic mixing

A

Occurs w/ simultaneous infxn of a cell w/ 2 viruses. Genome of virus A can be partially or completely coated (forming pseudovirion) w/ surface protein of virus B. Type B protein coat determines the infectivity of the phenotypically mixed virus. However, the progeny from this infxn have a type A coat that is encoded by its type A genetic material.

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8
Q

Viral vaccines

A

Live attenuated vaccines induce humoral and cell-mediated immunity, but have reverted to virulence on rare occasions. Killed vaccines induce only humoral immunity, but are stable. No boosters are needed for live-attenuated vaccines. It’s dangerous to give live vaccines to immunocompromised pts or their close contacts.

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9
Q

Important live attenuated vaccines

A

smallpox, yellow fever, chickenpox (VZV), Sabin’s polio, MMR

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10
Q

Important killed vaccines

A

Rabies, Influenza, Salk Polio, and HAV (RIP Always)

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11
Q

Important recombinant viral vaccines

A

HBV (Ag = recombinant HBsAg), HPV (types 6, 11, 16, and 18)

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12
Q

DNA viral genomes

A

All DNA viruses except the parvoviridae are dsDNA. All are linear except papilloma, polyoma, and hepadnaviruses (circular). All are dsDNA (like our cells), except part-of-a-virus (parvovirus)

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13
Q

RNA viral genomes

A

All RNA viruses except Reoviridae are ssRNA All are ssRNA (like our mRNA) except re peato virus (reo virus) is dsRNA

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14
Q

Naked viral genome infectivity

A

Purified nucleic acids of most sdDNA (except poxviruses and HBV) and (+)strand RNA (~mRNA) viruses are infectious. Naked nucleic acids of (-)strand ssRNA and dsRNA viruses are not infectious. They require enzymes contained in the complete viriion.

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15
Q

Virus ploidy

A

All viruses are haploid (w/ 1 copy of DNA or RNA) except retroviruses, which have 2 identical ssRNA molecules (~diploid)

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16
Q

Viral replication

A

DNA viruses all replicate in the nucleus (except poxvirus) All RNA viruses replicate in the cytoplasm (except influenza virus and retroviruses)

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17
Q

Non-enveloped viruses (list)

A

Naked (nonenveloped) viruses include: Calcivirus Picornavirus Reovirus Parvovirus Adenovirus Papilloma Polyoma Naked CPR and PAPP smear

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18
Q

Enveloped viruses

A

Generally, enveloped viruses acquire their envelopes from plasma membrane when they exit from the cell. Exceptions are herpesviruses, which acquire envelopes from the nuclear membrane.

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19
Q

DNA enveloped viruses (list)

A

Herpesviruses (HSV types 1 and 2, VZV, CMV, EBV), HBV, smallpox virus

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20
Q

DNA nucleocapsid viruses (list)

A

Adenovirus, papillomaviruses, parvovirus

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21
Q

RNA enveloped viruses (list)

A

Influenza virus, parainfluenza virus, RSV, measles virus, mumps virus, rubella virus, rabies virus, HTLV, HIV

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22
Q

RNA nucleocapsid viruses (list)

A

Enteroviruses (poliovirus, coxsackievirus, echovirus, HAV), rhinovirus, reovirus (rotavirus)

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23
Q

DNA viruses (list)

A

HHAPPPPy viruses! Hepadna Herpes Adeno Pox Parvo Papilloma Polyoma

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24
Q

All DNA viruses:

A

1.) Are double stranded (EXCEPT parvo: ssDNA) 2.) All are linear (EXCEPT papilloma and polyoma - circular, supercoiled and hepadna - circular, incomplete) 3.) Are icosahedral (EXCEPT pox: complex) 4.) Replicate in the nucleus (EXCEPT pox - carries own DNA-dep RNA pol)

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25
Q

Viral families: Herpesvirus Envelope? DNA strxr? Medical importance?

A

Enveloped. dsDNA, linear. HSV-1: oral (and some genital) lesions, keratoconjunctivitis HSV-2: genital (and some oral) lesions VZV: chickenpox, zoster, shingles EBV: mononucleosis, Burkitt’s lymphoma CMV: infxn in immunosuppressed pts, especially transplant recipients; congenital defects HHV-6: roseola (exanthem subitum) HHV-8: Kaposi’s sarcoma-associated virus (KSHV)

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26
Q

Viral families: Hepadnavirus Envelope? DNA strxr? Medical importance?

A

Enveloped. Partial circular dsDNA. HBV: Acute or chronic hepatitis. Vaccine available: use has increased tremendously. Not a retrovirus, but has reverse transcriptase.

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27
Q

Viral families: Adenovirus Envelope? DNA strxr? Medical importance?

A

Nonenveloped. Linear dsDNA Febrile pharyngitis - sore throat Pneumonia Conjunctivitis (pink eye)

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28
Q

Viral families: Parvovirus Envelope? DNA strxr? Medical importance?

A

Nonenveloped. Linear (-)ssDNA (smallest DNA virus). B19 virus: aplastic crises in sickle cell dz, slapped cheeks rash - erythema infectiosum (fifth dz), hydrops fetalis.

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29
Q

Viral families: Papillomavirus Envelope? DNA strxr? Medical importance?

A

Nonenveloped. Circular dsDNA HPV: warts, CIN, cervical cancer.

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30
Q

Viral families: Polyomavirus Envelope? DNA strxr? Medical importance?

A

Nonenveloped. Circular, dsDNA. JC: progressive multifocal leukoencephalopathy (PML) in HIV

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31
Q

Viral families: Poxvirus Envelope? DNA strxr? Medical importance?

A

Enveloped. Linear dsDNA (largest DNA virus). Smallpox, although eradicated, could be used in germ warfare. Vaccinia: cowpox (milkmaid’s blisters) Molluscum contagiosum.

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32
Q

Herpesviruses: HSV-1 Dz? Route of Transmission?

A

Dz: Gingivostomatitis keratoconjunctivitis temporal lobe encephalitis (most common cause of sporadic encephalitis in the USA) Herpes labialis Transmission: Respiratory secretions Saliva

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33
Q

Dz: Gingivostomatitis keratoconjunctivitis temporal lobe encephalitis (most common cause of sporadic encephalitis in the USA) Herpes labialis Transmission: Respiratory secretions Saliva

A

HSV-1

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34
Q

Herpesviruses: HSV-2 Dz? Route of Transmission?

A

Dz: Herpes genitalis [below] Neonatal herpes Transmission: Sexual contact Perinatal

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35
Q

Dz: Herpes genitalis [below] Neonatal herpes Transmission: Sexual contact Perinatal

A

HSV-2

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36
Q

Herpesviruses: VZV (Varicella-Zoster Virus) Dz? Route of Transmission?

A

Dz: Shingles (below) Encephalitis Pneumonia Transmission: Respiratory secretions *VZV remains dormant in the trigeminal and dorsal root ganglia.

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37
Q

Dz: Shingles (below) Encephalitis Pneumonia Transmission: Respiratory secretions *VZV remains dormant in the trigeminal and dorsal root ganglia.

A

VZV (Varicella-Zoster Virus)

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38
Q

Herpesviruses: EBV Dz? Route of Transmission?

A

Dz: Infectious mononucleosis Burkitt’s lymphoma Nasopharyngeal carcinoma Transmission: Respiratory secretions, saliva

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39
Q

Dz: Infectious mononucleosis Burkitt’s lymphoma Nasopharyngeal carcinoma Transmission: Respiratory secretions, saliva

A

EBV

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40
Q

Herpesviruses: CMV Dz? Route of Transmission?

A

Dz: Congenital infxn Mononucleosis (negative Monospot) Pneumonia. Infected cells have characteristic owl’s eye appearance (below) Transmission: Congenital Transfusion Sexual contact Saliva Urine Transplant

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41
Q

Dz: Congenital infxn Mononucleosis (negative Monospot) Pneumonia. Infected cells have characteristic owl’s eye appearance (below) Transmission: Congenital Transfusion Sexual contact Saliva Urine Transplant

A

CMV

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42
Q

Herpesviruses: HHV-8 Dz? Route of Transmission?

A

Dz: Kaposi’s sarcoma (in HIV pts) Transmission: Sexual contact

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43
Q

Dz: Kaposi’s sarcoma (in HIV pts) Transmission: Sexual contact

A

HHV-8

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44
Q

EBV

A

A herpesvirus. Can cause mononucleosis. Infects B cells. Also associated w/ development of Hodgkin’s and endemic Burkitt’s lymphomas, as well as nasopharyngeal carcinoma.

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45
Q

Mononucleosis due to EBV Sx/findings?

A

Fever, hepatosplenomegaly, pharyngitis, and lymphadenopathy (especially posterior cervical LNs). Abnormal circulating cytotoxic T-cells (atypical lymphocytes). Positive Monospot test.

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46
Q

When does EBV peak?

A

Peak incidence 15-20 yrs. Most common during peak kissing years (kissing dz)

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47
Q

Positive Monospot test

A

Heterophil Abs detected by agglutination of sheep RBCs (positive in EBV infxn)

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48
Q

Herpesviruses (list)

A

Get herpes in a CHEV rolet C MV H SV E BV V ZV

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49
Q

Tzanck test

A

A smear of an opened skin vesicle to detect multinucleated giant cells. Used to assay for HSV-1, HSV-2, and VZV. Tzanck heavens I don’t have herpes!

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50
Q

Cowdry A inclusions

A

Intranuclear inclusions shown in cells infected w/ HSV (would show up on Tzanck smear)

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51
Q

Viral family: Reoviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

No Envelope. dsRNA , linear, 10-12 segments Icosahedral (double) capsid Reovirus: Colorado tick fever Rotavirus: #1 cause of fatal diarrhea in children

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52
Q

No Envelope. dsRNA , linear, 10-12 segments Icosahedral (double) capsid Reovirus: Colorado tick fever Rotavirus: #1 cause of fatal diarrhea in children

A

Reoviruses

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53
Q

Viral family: Picornaviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

No envelope ss(+)RNA, linear Icosahedral capsid. Poliovirus: polio-Salk/Sabin vaccines – IPV/OPV Echovirus: aseptic meningitis Rhinovirus: common cold Coxsackievirus: aseptic meningitis, herpangina –febrile pharyngitis, hand, foot, and mouth dz, myocarditis HAV: acute viral hepatitis

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54
Q

No envelope ss(+)RNA, linear Icosahedral capsid. Poliovirus: polio-Salk/Sabin vaccines – IPV/OPV Echovirus: aseptic meningitis Rhinovirus: common cold Coxsackievirus: aseptic meningitis, herpangina –febrile pharyngitis, hand, foot, and mouth dz, myocarditis HAV: acute viral hepatitis

A

Picornaviruses

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55
Q

Viral family: Hepevirus Envelope? RNA structure? Capsid symmetry? Medical importance?

A

No envelope. ss(+)RNA, linear Icosahedral capsid. HEV

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56
Q

No envelope. ss(+)RNA, linear Icosahedral capsid. HEV

A

Hepevirus

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57
Q

Viral family: Calciviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

No envelope. ss(+)RNA, linear. Icosahedral capsid. Norwalk virus – viral gastroenteritis.

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58
Q

No envelope. ss(+)RNA, linear. Icosahedral capsid. Norwalk virus – viral gastroenteritis.

A

Calciviruses

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59
Q

Viral family: Flaviviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(+)RNA, linear. Icosahedral capsid. HCV Yellow fever* Dengue* St. Louis encephalitis* West Nile Virus* (*=arbovirus)

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60
Q

Enveloped. ss(+)RNA, linear. Icosahedral capsid. HCV Yellow fever* Dengue* St. Louis encephalitis* West Nile Virus* (*=arbovirus)

A

Flaviviruses

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61
Q

Viral family: Togaviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(+)RNA, linear. Icosahedral capsid. Rubella (German measles) Eastern equine encephalitis* Western equine encephalitis* (*=arbovirus)

62
Q

Enveloped. ss(+)RNA, linear. Icosahedral capsid. Rubella (German measles) Eastern equine encephalitis* Western equine encephalitis* (*=arbovirus)

A

Togaviruses

63
Q

Viral family: Retroviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(+)RNA, linear. Icosahedral capsid. Have reverse transcriptase HIV/AIDS HTLV - T-cell leukemia

64
Q

Enveloped. ss(+)RNA, linear. Icosahedral capsid. Have reverse transcriptase HIV/AIDS HTLV - T-cell leukemia

A

Retroviruses

65
Q

Viral family: Coronaviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(+)RNA, linear. Helical capsid. Coronavirus – common cold and SARS

66
Q

Enveloped. ss(+)RNA, linear. Helical capsid. Coronavirus – common cold and SARS

A

Coronaviruses

67
Q

Viral family: Orthomyxoviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)RNA, linear. 8 segments. Helical capsid. Inflenza virus.

68
Q

Enveloped. ss(-)RNA, linear. 8 segments. Helical capsid. Inflenza virus.

A

Orthomyxoviruses

69
Q

Viral family: Paramyxoviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)RNA, linear, nonsegmented. Helical capsid. P aR aM yxovirus: P arainfluenza – croup R SV – bronchiolitis in babies; Rx – ribavirin Rubeola (M easles) M umps

70
Q

Enveloped. ss(-)RNA, linear, nonsegmented. Helical capsid. P aR aM yxovirus: P arainfluenza – croup R SV – bronchiolitis in babies; Rx – ribavirin Rubeola (M easles) M umps

A

Paramyxoviruses

71
Q

Viral family: Rhabdoviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)RNA, linear. Helical capsid. Rabies.

72
Q

Enveloped. ss(-)RNA, linear.

A

Helical capsid. Rabies. Rhabdoviruses

73
Q

Viral family: Filoviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)RNA, linear. Helical capsid. Ebola/Marburg hemorrhagic fever – often fatal!

74
Q

Enveloped. ss(-)RNA, linear. Helical capsid. Ebola/Marburg hemorrhagic fever – often fatal!

A

Filoviruses

75
Q

Viral family: Arenaviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)circular RNA, 2 segments. Helical capsid. LCMV – lymphocyticc choriomeningitis virus. Lassa fever encephalitis – spread by mice.

76
Q

Enveloped. ss(-)circular RNA, 2 segments. Helical capsid. LCMV – lymphocyticc choriomeningitis virus. Lassa fever encephalitis – spread by mice.

A

Arenaviruses

77
Q

Viral family: Bunyaviruses Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)circular RNA, 3 segments. Helical capsid. California encephalitis* Sandflly/Rift Valley fevers Crimean-Congo hemorrhagic fever* Hantavirus – hemorrhagic fever, pneumonia (*=arbovirus)

78
Q

Enveloped. ss(-)circular RNA, 3 segments. Helical capsid. California encephalitis* Sandflly/Rift Valley fevers Crimean-Congo hemorrhagic fever* Hantavirus – hemorrhagic fever, pneumonia (*=arbovirus)

A

Bunyaviruses

79
Q

Viral family: Deltavirus Envelope? RNA structure? Capsid symmetry? Medical importance?

A

Enveloped. ss(-)circular RNA. Helical capsid. HDV.

80
Q

Enveloped. ss(-)circular RNA. Helical capsid. HDV.

A

Deltavirus

81
Q

Negative-stranded Viruses

A

Must transcribe (-) strand to (+) Virion brings its own RNA-dependent RNA polymerase. Include: A renaviruses B unyaviruses P aramyxoviruses O rthomyxoviruses F iloviruses R habdoviruses Always Bring Polymerase Or Fail Replication

82
Q

Segmented Viruses

A

All are RNA viruses. Include: B unyaviruses O rthomyxoviruses (influenza viruses) A renaviruses R eoviruses (BOAR ) Influenza virus has 8 segments of (-)RNA These segments undergo reassortment, causing antigenic shifts that lead to worldwide pandemics of the flu.

83
Q

Picornaviruses

A

Include: P oliovirus E chovirus R hinovirus C oxsackievirus H AV (PERCH on a ‘peak ‘ [pico]) RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins. Can cause aseptic (viral) meningitis (except rhinovirus and HAV). (PicoRNA virus = small RNA virus)

84
Q

Rhinovirus

A

A picornavirus. Nonenveloped RNA virus. Cause of common cold. (Rhino has a runny nose) >100 serologic types.

85
Q

Yellow fever virus

A

A flavivirus (also an arbovirus) transmitted by Aedes mosquitos. Virus has monkey or human reservoir. Sx: high fever, black vomitus, and jaundice. Councilman bodies (acidophilic inclusions) may be seen in liver. ( Flavi = yellow)

86
Q

Rubella virus

A

A togavirus. Causes German (3-day) measles: Fever, lymphadenopathy, arthralgias, fine truncal rash. Causes mild dz in children but serious congenital dz (a TORCH infxn)

87
Q

Rotavirus

A

The most important global cause of infantile gastroenteritis. Segmented dsRNA virus (a reovirus). Major cause of acute diarrhea in the USA during winter, especially in daycare centers, kindergartens. Villous destruction w/ atrophy leads to decreased absorption of Na+ and water. ROTA = R ight O ut T he A nus

88
Q

Influenza virus

A

Orthomyxoviruses. Enveloped, ssRNA, w/ segmented genome. Contain hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release) Ags. Responsible for worldwide influenza epidemics; pt at risk for fatal bacterial superinfeciton. Rapid genetic changes.

89
Q

A major mode of protection from influenza virus?

A

Killed viral vaccine. A reformulated vaccine is offered each fall to elderly, healthcare workers, etc.

90
Q

Influenza virus and genetic shift

A

(pandemic) Reassortment of viral genome (such as when human flu A virus recombines w/ swine flu A virus) S udden S hift is more deadly that graD ual D rift

91
Q

Influenza virus and gentic drift

A

(Epidemic) Minor (antigenic drift) changes based on random mutation. S udden S hift is more deadly that graD ual D rift

92
Q

Paramyxoviruses

A

Paramyxoviruses cause dz in children. They include those that cause: parainfluenza (croup: seal-like barking cough), mumps , measles , and RSV (which causes repiratory tract infection [bronchiolitis, pneumonia] in infants)

93
Q

Rubeola (measles) virus

A

A paramyxovirus that causes measles. Koplik spots (red spots w/ blude-white center on buccal mucosa [below]) are diagnostic. SSPE (yrs later), encephalitis (1:2000), and giant cell pneumonia (rarely, in immunosuppressed) are possible sequelae. Rash spreads from head to toe [below]

94
Q

3C’s of Measles

A

C ough C oryza (head cold) C onjunctivitis *Also look for K oplik spots (not actually a C, but close enough)

95
Q

Mumps virus

A

A paramyxovirus. Sx: P arotitis O rchitis (inflammation of the testes)* [aseptic] M eningitis Mumps makes your parotid glands and testes as big as POM -poms *Can cause sterility (especially after puberty)

96
Q

Rabies virus

A

Negri bodies are characteristic cytoplasmic inclusions in neurons affected by rabies viru: Bullet shaped capsid: Rabies has a long incubation period (wks-months), which allows for immunization after exposure. Causes fatal encephalitis w/ seizures, hydrophobia, hypersalivation, and pharyngeal spasm. Travels to CNS by migrating in a retrograde fashion up nerve axons.

97
Q

How is rabies virus more commonly contracted in the USA?

A

Bat, raccoon, and skunk bites > dog bites (in USA)

98
Q

Arbovirus

A

Transmitted by arthropods (mosquitoes, ticks). Classic examples: dengue fever (aka break-bone fever) and yellow fever . A variant of dengue fever in SE Asia is hemorrhagic shock syndrome . ARBO virus = AR thropod-BO rne virus Includes some members of F lavivirus, T ogavirus, and B unyavirus: F ever T ransmitted by B ites

99
Q

Lots of spots: Rubella

A

Togavirus; German 3-day measles.

100
Q

Lots of spots: Rubeola

A

Paramyxovirus; measles.

101
Q

Lots of spots: Varicella

A

Herpesvirus; chickenpox and zoster.

102
Q

Lots of spots: Variola

A

Poxvirus; smallpox (no longer present outside of labs).

103
Q

How many families of Hepatitis viruses are there?

A

5: HAV HBV HCV HDV HEV

104
Q

HAV

A

RNA picornavirus. Transmitted primarily by fecal-oral route. Short incubation (3 weeks). No carriers. HepA is A symptomatic (usually) A cute, A lone (no carriers)

105
Q

HBV

A

DNA hepadnavirus. Transmitted primarily by parenteral, sexual, and maternal-fetal routes. HepB = B lood-B orne Long incubation (3 months). Carriers. Cellular RNA polymerase transcribes RNA from DNA template. Reverse transcriptase transcribes DNA genome from RNA intermediate. However, the virion enzyme is a DNA-dependent DNA polymerase .

106
Q

HCV

A

RNA flavivirus. Transmitted primarily via blood and resembles HBV in its course and severity. Carriers. Common cuase of post-transfusion hepatitis and of hepatitis among IV drug users in the USA. HepC = C hronic, C irrhosis, C arcinoma, C arriers.

107
Q

HDV

A

Delta agent. A defective virus that requires HBsAg as its envelope. HDV can coinfect w/ HBV or superinfect; the latter has a worse prognosis. Carriers. HepD = D efective, D ependent on HBV.

108
Q

HEV

A

RNA hepevirus. Transmitted enterically and causes water-borne epidemics. Resembles HAV in course, severity, incubation. High mortality rate in pregnant women. HepE = E nteric, E xpectant mothers, E pidemics

109
Q

Both HBV and HCV…

A

… predispose pt to chronic active hepatitis, cirrhosis, and hepatocellular carcinoma.

110
Q

HepA and HepE are transmitted…

A

… via the fecal-oral route. The vowels hit your bowels .

111
Q

IgG HAVAb

A

Indicates prior infection; protective against reinfection.

112
Q

IgM HAVAb

A

IgM Ab to HAV; best test to detect active hepatitis A.

113
Q

HBsAg

A

Ag found on surface of HBV; continued presence indicates carrier state.

114
Q

HBsAb

A

Ab to HBsAg; provides immunity to hepatitis B.

115
Q

HBcAg

A

Ag associated w/ core of HBV

116
Q

HBcAb

A

Ab to HBcAg; positive during window period [see below]. IgM HBcAb is an indicator of recent dz. IgG HBcAb signifies chronic dz.

117
Q

HBe Ag

A

A second, different antigenic determinant in the HBV core. Important indicator of active viral replication and therefore transmissibility. Be ware!

118
Q

HBeAb

A

Ab to e antigen ; indicaters low transmissibility.

119
Q

Viral vs. alcoholic hepatitis (liver enzymes)

A

Viral hepatitis: ALT > AST Alcoholic hepatitis: AST > ALT

120
Q

When do you see HBsAg?

A

acute disease [not in window phase] [not in complete recovery] chronic carrier state [not in immunized]

121
Q

When do you see HBsAb?

A

[Not in acute dz] [In window phase, basically no. (Pt has surface Ab, but available Ab is bound to HBsAg, so not detected by assay)] Complete Recovery [not in chronic carrier state] Immunized

122
Q

When do you see HBcAb?

A

Acute Disease (IgM in acute stage; IgG in chronic or recovered stage) Window Phase Complete Recovery Chronic Carrier State [not in immunized]

123
Q

What HBV Ag/Ab’s would show up in acute disease?

A

HBsAg and HBcAb [not: HBsAb]

124
Q

What HBV Ag/Ab’s would show up in the window phase?

A

HBcAb only.

125
Q

What HBV Ag/Ab’s would show up in complete recovery?

A

HBsAb and HBcAb. [not: HBsAg]

126
Q

What HBV Ag/Ab’s would show up in chronic carrier state?

A

HBsAg and HBcAb. [not: HBsAb]

127
Q

What HBV Ag/Ab’s would show up in immunized individuals?

A

HBsAb only.

128
Q

HIV structure and proteins

A
129
Q

HIV’s genome

A

Diploid (2 molecules of RNA, but not dsRNA).

130
Q

HIV: p24

A

Capsid protein

131
Q

HIV: gp41 and gp120

A

Envelope proteins.

132
Q

Function of reverse transcriptase in HIV

A

Synthesizes dsDNA from RNA. dsDNA integrates into host genome.

133
Q

HIV virus binding

A

Virus binds CXCR4 and CD4 on T-cells; binds CCR5 and CD4 on macrophages. Homozygous CCR5 mutation = immunity. Heterozygous CCR5 mutation = slower course.

134
Q

ELISA and HIV dx

A

Used for presumptive diagnosis (sensitive, high false-positive rate and low threshold, RULE OUT test); postitive results are then confirmed w/ Western blot assay (specific, high false-negative rate and high threshold, RULE IN test). ELISA/Western blot tests look for Abs to viral proteins; these tests are often falsely negative in the first 1-2 months of HIV infxn and falsely positive initially in babies born to infected mothers (angti-gp120 crosses placenta).

135
Q

PCR/viral load and HIV

A

Tests are increasing in poluarity: allow the physician to monitor the effect of drug therapy on viral load.

136
Q

AIDS diagnosis

A

< or = 200 CD4+, HIV positive w/ AIDS indicator condition (e.g., PCP) or CD4/CD8 ratio <1.5

137
Q

4 stages of HIV infxn

A

1.) F lu-like (acute) 2.) F eeling fine (latent) 3.) F alling count 4.) F inal crisis During latent phase, virus replicates in LN’s

138
Q

Levels as HIV infxn progresses: CD4+ lymphocytes? Anti-p24 Abs? Anti-gp120 Abs? Virus, p24 Ag?

A

CD4+ T-cells have an early dip, stabilize, and fall during stages 3-4 (years after infxn) Anti-p24 and Anti-gp120 Abs rise starting ~1 mo. post-infxn, stabilize @ 3 mos (at end of acute infxn). Virus, p24 Ag: spike early (w/ start of acute Sx’s), drop to low level until stages 3-4 (years later), when they take off

139
Q

Organ system affected in AIDS: Brain (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Crytococcal meningitis Toxoplasmosis CMV encephalopathy AIDS dementia PML (JC virus)

140
Q

Organ system affected in AIDS: Eyes (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: CMV retinitis

141
Q

Organ system affected in AIDS: Mouth and throat (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Thrush (Candida albicans) HSV CMV Oral hairy leukoplakia (EBV)

142
Q

Organ system affected in AIDS: Lungs (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Pneumocystis jiroveci pneumonia (PJP) TB histoplasmosis

143
Q

Organ system affected in AIDS: GI (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Cryptosporidiosis Mycobacterium avium-intracellulare complex CMV colitis Non-Hodgkin’s lymphoma (EBV) Isopora belli

144
Q

Organ system affected in AIDS: Skin (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Shingles (VZV) Kaposi’s sarcoma (HHV-8)

145
Q

Organ system affected in AIDS: Genitals (what is the infxn/dz associated?)

A

Infxn/dz associated w/ AIDS: Genital herpes warts cervical cancer (HPV)

146
Q

HIV-assicated infxns that increase in risk at CD4+ count: < 400

A

Infxn: Oral thrush Tinea pedis (athlete’s foot) Reactivation VZV Reactivation tuberculosis Other bacterial infxns (e.g., H. influenzae, S. pneumoniae, Salmonella)

147
Q

HIV-assicated infxns that increase in risk at CD4+ count: < 200

A

Infxn: Reactivation HSV cryptosporidosis Isopora Disseminated coccidioidomycosis Pneumocystis pneumonia

148
Q

HIV-assicated infxns that increase in risk at CD4+ count: < 100

A

Infxn: Candidal esophagitis Toxoplamosis histoplasmosis

149
Q

HIV-assicated infxns that increase in risk at CD4+ count: < 50

A

Infxn: CMV retinitis and esophagitis Disseminated M. avium-intracellulare Cryptococcal meningitis

150
Q

Neoplasms associated w/ HIV

A

Kaposi’s sarcoma (HHV-8) Invasive cervical carcinoma (HPV) Primary CNS lymphoma non-Hodgkin’s lymphoma

151
Q

HIV encephalitis

A

Occurs late in the course of HIV infxn. Virus gains CNS access via infected Macrophages. Microglial nodules w/ multinucleated giant cells.

152
Q

Prions What are they? What dz’s do they cause? Normal vs. pathologic prions?

A

Infectious agents that do not contain RNA or DNA (consist only of proteins); encoded by cellular genes. Dz’s: Creutzfeldt-Jakob dz (CJD – rapidly progressive dementia), kuru, srapie (sheep), mad cow dz Associated w/ spongiform encephalopathy . Normal prions have alpha-helix conformation; pathologic prions (like CJD) are beta-pleated sheets. Pathologic conformation accumulates b/c it is resistant to proteinase digestion.

USMLE1 - Microbiology (7 decks)

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