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NBDE Part 1 > Microbiology Virology > Flashcards

Microbiology Virology Flashcards

1
Q

What is a Virion and how are viruses characterized?

A
  • Virion: Infectious; complete virus particle (DNA/RNA + protein)
  • Virus Characterization:
    • Characterized by single- or double-stranded DNA or RNA (never both) surrounded by a protein capsid
      • Repeating polypeptide subunits (capsomeres)
      • Protects viral genome from extracellular nucleases
      • Essential for infectivity of virus
      • Antigenic; provokes host immune response
      • Serves as attachment protein in nonenveloped viruses
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2
Q

Explain haploid/diploid nature of viruses as well as where RNA and DNA viruses replicate and their hardware

A
  • All viruses are haploid (1 copy of RNA/DNA)
    • EXCEPT: Retroviruses = diploid
  • All RNA viruses replicate in the cytoplasm using their own RNA polymerase
    • EXCEPT: retrovirus and orthomyxovirus
  • All DNA viruses replicate in the nucleus using host RNA polymerase
    • EXCEPT: poxvirus
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3
Q

What are the following:

  • Nucleocapsid
  • Envelop
  • Viroid
A
  • Nucleocapsid: Nucleic acid core + protein capsid
  • Some viruses have an outer membrane called an envelope, which is composed of plasma membrane lipoproteins and glycoproteins obtained as the virus leaves its host cell (budding)
  • Viroid: a Single molecule of circular RNA without a protein envelope. Causes plan diseases
  • Virus Facts:
    • Do not contain mitochondria or ribosomes; must replicate within living host cells
    • Not visible by light microscopy
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4
Q

Explain the viral growth curve

A
  • Latent phase: Viral penetration -> viral release 10-12 hours
  • Eclipse phase: viral penetration -> viral assembly within host cell.
    • No virus can be detected during this phase
  • Rise phase: Viral assembly -> viral release
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5
Q

Explain Viral Replication steps

A
  • Attachment: Determined by the specificity of viral proteins to host cells
  • Penetration: Via receptor-mediated endocytosis (eg. pinocytosis)
  • Uncoating: Viral nucleic acid is spilled into the cytoplasm
  • Transcription and Translation:
    • All DNA viruses (except poxviruses) replicate in the nucleus using host cell RNA polymerase
    • All RNA viruses (except retroviruses and orthomyxoviruses) replicate in the cytoplasm using their RNA polymerase. Transcription is only necessary for viruses whose RNA has a negative polarity (a virus’s RNA that has positive polarity serves as the mRNA itself)
    • All Retroviruses use their own reverse transcriptase for transcription
  • Assembly : The new viral nucleic acid and capsid proteins are packaged
  • Released : Either by budding through the host plasma membrane (creating a viral envelope) or by host plasma membrane rupture
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6
Q

Explain the following viruses and terminologies:

  • Cytopathic effect (CPE)
  • Enteroviruses
  • Roboviruses
  • Arboviruses
A
  • One virion can replicate to form hundreds of progeny viruses
  • The host cellular morphologic and functional changes associated with viral replication and release are known as the cytopathic effect (CPE).
    • CPE is often specific for a particular virus. Not all viruses cause CPE
  • Enteroviruses : Poliovirus, Coxsackieviruses and hepatitis A
  • Roboviruses: Are rodent-borne viruses (rodent excrement): hantavirus (sin Nombe viruses)
  • Arboviruses : are arthropod-borne viruses (mosquitoes, ticks): West Nile virus, yellow fever virus, Dengue virus, Colorado tick fever virus and Eastern/Western encephalitis virus
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7
Q

Describe the structure of HIV

A
  • HIV contains two strands of RNA (diploid) and reverses transcriptase
  • Two important envelope protein:
    • gp120 (mediates attachment to CD4)
    • gp41 (mediates fusion to the host cell)
  • The nucleocapsid is composed of p24 and p7
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8
Q

Explain viral antigenic changes

A
  • Antigenic changes contribute to the cause of epidemic and pandemics
  • Commonly associated with influenza viruses (orthomyxoviruses)
  • There are two modes of antigenic changes:
    • Antigenic drift : Minor changes caused by genetic mutations
    • Antigenic shift : Major changes caused by genetic reassortment

NOTE: Influenza viruses have two envelope glycoprotein spikes, hemagglutinin and neuraminidase, which exhibit the majority of antigenic changes

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9
Q

Name the RNA Nonenveloped Viruses in order of increasing size

A
  • Picornavirus (smallest RNA) - single/linear
  • Calicivirus - Single/linear
  • Hepevirus - Single/linear
  • Reovirus - Double/linear
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10
Q

What makes up the Picornaviruses

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

Picornaviruses​​

  • Poliovirus (single, linear)
    • Polio
      • Antiviral: None
      • Vaccine: Yes (Salk, Sabin)
  • Echovirus (single, linear)
    • Aseptic meningitis
      • Antiviral: None
      • Vaccine: No
  • Rhinovirus (single, linear)
    • Common Cold
      • Antiviral: None
      • Vaccine: No
  • Coxsackie A Virus (single, linear)
    • Herpangia: (soft palate, posterior pharynx)
    • Hand-Foot-&-Mouth disease: (Palms, soles, anterior oral mucosa)
    • Acute lymphonodular pharyngitis
    • Aseptic meningitis
      • Antiviral: None
      • Vaccine: No
  • Coxsackie B Virus (single, linear)
    • Pleurodynia
    • Myocarditis
    • Pericarditis
    • Aseptic meningitis
      • Antiviral: None
      • Vaccine: No
  • HAV (single, linear)
    • Hepatitis A
      • Antiviral: None
      • Vaccine: YES
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11
Q

What makes up the Calicivirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

Calicivirus

  • Norwalk virus (single, linear)​
    • Gastroenteritis (adults)
      • Antiviral: None
      • Vaccine: No
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12
Q

What makes up the Hepevirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

Hepevirus

  • HEV (single, linear)
    • Hepatitis E
      • Antiviral: None
      • Vaccine: No
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13
Q

What makes up the Reovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Reovirus

  • 1: Rotavirus (double; linear)
    • Gastroenteritis (infants)
      • Antiviral: None
      • Vaccine: No
  • 2: Coltivirus (double; linear) - only virus transmitted by ticks
    • Colorado tick fever
      • Antiviral: None
      • Vaccine: No
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14
Q

Name the RNA-Enveloped Viruses in order of increasing Size

A
  • Deltaviruse (Single, circular)
  • Flavivirus (Single, linear)
  • Togavirus (Single, linear)
  • Orthomyxovirus (Single, linear)
  • Retrovirus (Single, linear)
  • Paramyxovirus (Single, linear)
  • Rhabdovirus (Single, linear)
  • Filovirus (Single, linear)
  • Coronavirus (Single, linear)
  • Bunyavirus (Single, circular)
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15
Q

What makes up the Deltavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Deltavirus

  • HDV (single; circular)
    • Hepatitis D
      • Antiviral: alpha-interferon
      • Vaccine: Yes
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16
Q

What makes up the Flavivirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Flavivirus

  1. Japanese encephalitis virus (single, linear)
    • Encephalitis
      • Antiviral: None
      • Vaccine: Yes
  2. Yellow fever virus (single, linear)
    • Yellow fever
      • Antiviral: None
      • Vaccine: Yes
  3. West Nile Virus (single, linear)
    • Encephalitis
      • Antiviral: None
      • Vaccine: No
  4. Dengue Virus (single, linear)
    • Dengue fever
      • Antiviral: None
      • Vaccine: No
  5. HCV (single, linear)
    • Hepatitis C
    • Hepatocellular Carcinoma (associated)
      • Antiviral: alpha-interferon, Ribavirin
      • Vaccine: NO
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17
Q

What makes up the Togavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Togavirus

  1. Rubella virus (single, linear)
    • Rubella (German 3-day measles) Truncal rash, Teratogen
      • Antiviral: None
      • Vaccine: YES
  2. Eastern/Western encephalitis virus (single, linear)
    • Encephalitis
      • Antiviral: None
      • Vaccine: No
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18
Q

What makes up the Orthomyxovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Orthomyxovirus

Exhibit various antigenic changes

Replicate in nucleus

  • Influenza Virus (single, linear)
    • Influenza
    • Reye’s Syndrome (association)
      • Antiviral: Amantidine, Rimantidine, Zanamivir, Oseltamivir
      • Vaccine: YES
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19
Q

What makes up the RETROVIRUS

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the RETROVIRUS

Uses reverse transcriptase

Replicates in nucleus

Diploid

  1. HTLV (single, linear)
    • Adult T-cell leukemia/lymphoma
    • Chronic progressive myelopathy
      • Antiviral: None
      • Vaccine: No
  2. HIV (single, linear)
    1. Infects CD4 T-helper cells
    2. Diagnosis confirmed by Western blot
      • AIDS
        • Antiviral: Zidovudine (AZT), Lamivudine, Stavudine, Indinavir, Ritonavir
        • Vaccine: No
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20
Q

What makes up the Paramyxovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Paramyxovirus

  1. Measles virus (single, linear)
    • Measles (rubeola)
      • Nonpruritic maculopapular brick-red rash
      • Multiple white lesions (Koplik’s spots) are often seen on the buccal mucosa
        • Antiviral: None
        • Vaccine: YES
  2. Mumps virus (single, linear)
    • Mumps
      • Parotitis, orchitis, deafness​
        • Antiviral: None
        • Vaccine: YES
  3. RSV = INFANTS ONLY (single, linear)
    • Bronchiolitis
    • Pneumonia
      • Antiviral: Ribavirin
      • Vaccine: No
  4. Parainfluenza virus (single, linear)
    • Croup
    • Bronchiolitis
    • Common cold
      • Antiviral: None
      • Vaccine: No
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21
Q

What makes up the Rhabdovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Rhabdovirus

  • Rabies Virus (single, linear)
    • Rabies
      • Antiviral: None
      • Vaccine: YES
22
Q

What makes up the Filovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Filovirus

  • Ebola Virus (single, linear)
    • Ebola
    • Hemorrhagic Fever
      • Antiviral: None
      • Vaccine: No
23
Q

What makes up the Coronavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Coronavirus

  • Coronavirus (single, linear)
    • Common Cold
    • SARS
      • Antiviral: None
      • Vaccine: No
24
Q

What makes up the Bunyavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Bunyavirus

  • Hantavirus = Sin Nombre virus (single, circular)
    • Hantavirus
    • Hemorrhagic Fever
      • Antiviral: None
      • Vaccine: No
25
Q

Which virus causes the following diseases:

  • Herpangia
    • Soft palate, posterior pharynx
  • Hand-foot and mouth disease
    • Palms, soles, anterior oral mucosa
  • Acute lymphonodular pharyngitis
  • Aseptic Meningitis
A

Coxsackie A virus

(Family: Picornavirus = Smallest RNA Virus)

Nonenveloped (single, linear)

26
Q

What virus causes the following diseases:

Gastroenteritis (infants)

A

Rotavirus

(Family: Reovirus)

RNA Nonenveloped: Double, linear

In addition, Coltivirus also belongs in this family

  • only virus transmitted by ticks
    • Colorado tick fever
27
Q

Which virus family includes the following diseases and/or viruses:

  • West Nile
  • Yellow Fever
  • HCV = Hepatitis C
A

Flavivirus

RNA-Enveloped virus

28
Q

Which virus family includes the following diseases and/or viruses:

  • HTLV and HIV
A

Retrovirus

RNA-Enveloped Virus

  • Uses reverse transcriptase
  • Replicates in the nucleus
  • diploid
29
Q

Which virus family includes the following diseases and/or viruses:

  • Rubella virus (Rubella = German 3 day measles)
A

Togavirus

Includes Rubella virus = Rubella

(German 3 day measles)

Truncal rash

Teratogen

30
Q

Which virus family includes the following diseases and/or viruses:

Measles Virus

Mumps Virus

RSV

Parainfluenza Virus

A

Paramyxovirus

RNA Enveloped Virus

  • Measles Virus
    • Measles (rubeola)
  • Mumps Virus
    • Mumps
  • RSV (Infants only)
    • Bronchiolitis, Pneumonia
  • Parainfluenza Virus
    • Croup
31
Q

What virus is characterized by:

  1. Nonpruritic maculopapular brick-red rash
  2. Multiple white lesions on the buccal mucosa
A

Measles (Rubeola)

  1. Nonpruritic maculopapular brick-red rash
  2. Multiple white lesions on the buccal mucosa
    1. KOPLIK’S SPOTS
32
Q

What are the major DNA Nonenveloped viruses in order of increasing size

A
  • Parvovirus (Single, Linear)
  • Papillomavirus (Double, circular)
  • Polyomavirus (Double, circular)
  • Adenovirus (Double, linear)
33
Q

What makes up the Parvovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Parvovirus

Note: ParVovirus

  • B19 Virus (DNA Non - single; linear)
    • Aplastic anemia (Sickle cell disease associated)
    • Erythema infectiosum (fifth disease)
    • Fetal infections
      • Antiviral: None
      • Vaccine: No
34
Q

What makes up the Papillomavirus (Papovaviruses)

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Papillomavirus (Papovaviruses)

  • HPV (DNA non- double; circular)
    • Papillomas (warts)
    • Condyloma acuminatum (genital warts)
    • Verruca vulgaris
    • Cervical cancer
      • Antiviral: Podophyllin, alpha-interferon, Cidofovir
      • Vaccine: YES
35
Q

What makes up the polyomavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the polyomavirus

  • JC virus (DNA non- double; circular)
    • Progressive multifocal leukoencephalopathy (PML)
    • HIV associated
      • Antiviral: None
      • Vaccine: NO
36
Q

What makes up the Adenovirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Adenovirus

  • Adenovirus (DNA non - double; linear)
    • Pharyngitis
    • Conjunctivitis (pink eye)
    • Pneumonia
    • Common cold (children = Aden of children)
      • Antiviral: None
      • Vaccine: YES
37
Q

What are the major DNA enveloped viruses from smallest to largest

A
  • Hepadnavirus
  • Herpesvirus
  • Poxvirus
38
Q

What makes up the Hepadnavirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Hepadnavirus

Has reverse transcriptase

  • HBV (DNA Env. double; circular)
    • Hepatitis B
      • Hepatocellular carcinoma (associated)
        • Antiviral: alpha-interferon, Lamivudine
        • Vaccine: YES
39
Q

What makes up the Herpesvirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Herpesvirus

Lies dormant in sensory nerve ganglia, esp. trigeminal ganglion

Obtains envelope from host nuclear membrane (not plasma membrane)

Tzanck test assay for HSV-1, HSV-2, VZV

  1. HSV-1 (DNA Env double; linear)
    • Herpes labialis
    • Keratoconjunctivitis
    • Gingivostomatitis
    • Recurrent encephalitis
      • Antiviral: Acyclovir, Penciclovir, Valacyclovir, Famciclovir
      • Vaccine: No
  2. HSV-2 (DNA Env double; linear)
    • Herpes genitalis
    • Neonatal encephalitis
    • Aseptic meningitis
      • Antiviral: Acyclovir, Penciclovir, Valacyclovir, Famciclovir
      • Vaccine: No
  3. VZV (DNA Env double; linear)
    • Varicella - primary
      • Chickenpox
      • Pruritic, macular lesions that become pustular and crusted
      • Reye’s syndrome (associated)
    • Zoster - recurrent
      • Shingles
      • Usually localized to a single dermatome
        • Antiviral: Acyclovir, Valacyclovir, Famciclovir
        • Vaccine: No
  4. CMV (DNA Env double; linear)
    • Congenital abnormalities
      • Primary viral cause of mental retardation
    • Cytomegalic inclusion disease
      • Antiviral: Ganciclovir, Valganciclovir, Foscarnet
      • Vaccine: No
  5. EBV Ebstein Barr (DNA Env double; linear)
    • Infectious mononucleosis
      • Transmission: Saliva
        • ​​“kissing disease”
      • Splenomegaly, necrotizing pharyngitis, increased abnormal lymphocytes
      • Heterophile test used for screening
    • Burkitt’s lymphoma (association)
    • Nasopharyngeal carcinoma (association)
    • B-cell lymphoma (association)
    • Hairy leukoplakia (association)
      • Antiviral: None (self-limiting in 2-3 weeks)
      • Vaccine: No
  6. HHV-8 (DNA Env double; linear)
    • Kaposi’s Sarcoma
      • Antiviral: None
      • Vaccine: No
40
Q

What makes up the Poxvirus

  • Virus Name (single/double; linear/nonlinear)
    • Disease
      • Antiviral treatment available
      • Vaccine available
A

What makes up the Poxvirus

  1. Variola virus (DNA Env - double; linear)
    • Smallpox = ERADICATED
      • Antiviral: None
      • Vaccine: YES
  2. MCV (DNA Env - double; linear)
    • Molluscum contagiosum
      • Antiviral: None
      • Vaccine: No
41
Q

What are the signs and symptoms of viral hepatitis?

A

fatigue

myalgia

loss of appetite

nausea

diarrhea

constipation

fever

jaundice

Hepatitis viruses are extremely heat resistant (more so than HIV) proper autoclaving kills all hepatitis viruses

42
Q

What are the tests of liver function and how they rate to viral hepatitis and alcoholic hepatitis

A

Tests of liver function

  • Bilirubin
  • ALT (alanine aminotransferase)
  • AST (aspartate aminotransferase)

Viral vs. alcoholic hepatitis:

  • Viral hepatitis: ALT > AST
  • Alcoholic hepatitis: ALT < AST
43
Q

Compare the major Hepatitis viruses.

State their:

  • Virus
    • Nucleic acid
    • Viral Class
    • Transmission
    • Characteristics
    • Vaccine: Y/N
A
  • HAV
    • ss RNA
    • Picornavirus - No Env
    • Fecal-oral
    • Self-limiting; recovery in 4 months
    • Vaccine: Yes
  • HBV
    • ds DNA
    • Hepadnavirus - Yes Enveloped
    • Bloodborne
    • Increased incidence of chronic liver disease, cirrhosis, HCC
    • Vaccine: Yes
  • HCV
    • ss RNA
    • Flavivirus - Yes Enveloped
    • Bloodborne
    • Increased incidence of chronic liver disease, cirrhosis, HCC
    • Vaccine: No
  • HDV
    • ss RNA
    • Deltavirus - Yes Enveloped
    • Bloodborne
    • Requires presence of HBsAg for replication
    • Vaccine: Yes
  • HEV
    • ss RNA
    • Calicivirus - Not Enveloped
    • Fecal-oral
    • Causes occasional epidemics in underdeveloped countries
    • Vaccine: No
44
Q

Explain the serological profile of Hepatitis infections

  • Virus
    • Acute infection
    • Chronic disease
    • Immunity
A
  • HAV
    • Acute infection: IgM Anti-HAV
    • Chronic disease: None
    • Immunity: Anti-HAV
  • HBV
    • Acute infection: IgM Anti-HAB , HBsAg, HBeHg
    • Chronic disease: IgG Anti-HBc, HBsAg
    • Immunity: Anti-HBs
      • An individual vaccinated for HBV will show serology positive for ONLY Anti-HBs
  • HCV
    • Acute infection: Anti-HCV
    • Chronic disease: Anti-HCV
    • Immunity: Anti-HCV
      • HCV = most common reason for liver transplant in the US
  • HDV
    • Acute infection: IgM Anti-HDV
    • Chronic disease: Anti-HDV
    • Immunity: Anti-HDV
  • HEV
    • Acute infection: IgM Anti-HEV
    • Chronic disease: NONE
    • Immunity: Anti-HEV
45
Q

What are the types of viral Vaccinations?

A
  • Live attenuated
    • Conferred Immunity: Active
      • IgA, IgG, Tc-cell
    • Protection: Slow onset, longest lasting
      • Do not give to immunocompromised or pregnant women
    • Treated Diseases: Measles, Mumps, Rubella, Polio (Sabin): oral, Chickenpox, Smallpox
  • Killed virus
    • Conferred Immunity: Active
      • IgG
    • Protection: Slow onset, long lasting
    • Treated Diseases: Rabies, Influenza, Polio (salk): injection, Hepatitis A
  • Purified Viral Protein Subunits
    • Conferred Immunity: Active
    • Protection: Slow onset, long lasting
    • Treated Diseases: Hepatitis B via HBSAg
  • Preformed antibody
    • Conferred Immunity: Passive
    • Protection: Fast onset, Short life span
    • Treated Diseases: Rabies, Hepatitis B, Shingles
      • Can be given after exposure
46
Q

What is the antiviral drug

Interferons

A

Interferons

  • Glycoproteins that originate from infected host cells to protect other non-infected host cells
  • Do not directly affect viruses, but instead nonspecifically prevent their replication within host cells
  • Block various stages of viral RNA/DNA synthesis
  • INF-alpha: treats chronic hepatitis B and C
  • Toxicity: neutropenia
47
Q

What are

Bacteriophages (Phages)

A

Bacteriophages (Phages)

  • Viruses that infect bacteria cells
  • Replication can occur by two pathways:
    • Lytic cycle: the process by which some phages replicate within the host cell, producing hundreds of new progeny phage. The host cell is ultimately destroyed
      • Enterobacteria phage T4: phage that infects E. coli
    • Lysogenic cycle: The process by which some phages incorporate their DNA in the host cell chromosome. The integrated viral DNA is called a prophage. Replication occurs only when the host DNA is damaged, excising the viral DNA. The host cell is usually not destroyed
48
Q

What are

Lysogenic conversion

A

Alteration of the host bacterium to a pathogenic strain via expression of the integrated prophage genes.

Eg. Corynebacterium diphtheriae producing diphtheria toxin

49
Q

What are:

Prions

A
  • Infectious agents composed entirely of protein (no nucleic acid)
  • Do not elicit inflammatory or antibody responses
  • Causes transmissible spongiform encephalopathy:
    • Creutzfeldt-Jakob disease (in humans)
    • Mad cow disease (in cows)

NBDE Part 1 (7 decks)

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