Micro - Virology Part 1 Flashcards
1
Q
A recent renal transplant recipient has fever, malaise, allograft dysfunction, and cells with “owl’s eye” inclusions. Diagnosis?
A
CMV infection
2
Q
What are the two components of the naked icosahedral virus structure?
A
Nucleocapsid and nucleic acid
3
Q
What are the four components of an enveloped icosahedral virus structure?
A
Surface protein, lipid bilayer, capsid, and nucleic acid
4
Q
What are the four components of the enveloped helical virus structure?
A
Surface protein; matrix or core protein; lipid bilayer; and nucleic acid and
nucleocapsid protein
5
Q
Structurally, what are the three main classes of viruses?
A
Naked icosahedral, enveloped icosahedreal, enveloped helical
6
Q
In viral genetics, what is recombination?
A
It is the exchange of genes between two chromosomes by crossing over within
regions of significant base sequence homology
7
Q
In viral genetics, what is reassortment?
A
It is the exchange of segments among viruses with segmented genomes (eg,
influenza virus)
8
Q
Which type of viral genetic event can cause worldwide pandemics?
A
Reassortment, which happens when viruses with segmented genomes (eg,
influenza virus) exchange segments
9
Q
In viral genetics, when does complementation occur?
A
Complementation occurs when one of two viruses that infect the cell has a mutation that results in a nonfunctional protein and the nonmutated virus makes a functional protein that serves both viruses (the nonmutated virus “complements” the mutated one)
10
Q
In viral genetics, when does phenotype mixing occur?
A
Phenotype mixing occurs when the genome of virus A is coated with the surface
proteins of virus B and infectivity is determined by the virus B protein coat, but the
progeny is encoded by virus A generic material and will have the virus A coat
11
Q
Viral genome reassortment occurs in viruses with what type of genomic structure?
A
Segmented genomes
12
Q
What is a pseudovirion?
A
The genetic material of one virus coated by the surface proteins of a different virus
13
Q
What is the difference between the immunity induced by a live, attenuated virus
and that of killed virus vaccines?
A
Live, attenuated vaccines induce humoral and cell-mediated immunity whereas
killed vaccines induce only humoral immunity
14
Q
What is the advantage of killed vaccines over live, attenuated vaccines?
A
Killed vaccines are more stable, whereas live, attenuated vaccines have reverted to
virulence on very rare occasions
15
Q
Live vaccines are dangerous to give to which populations?
A
Immunocompromised patients or their contacts
16
Q
Name five live, attenuated vaccines.
A
MMR (measles, mumps, rubella), Sabin polio, varicella zoster virus, yellow fever,
smallpox (remember: “Live! One night only! See small yellow chickens get
vaccinated with Sabins and MMR”)
17
Q
Name four killed virus vaccines.
A
Rabies, Influenza, Salk Polio, and hepatitis A virus (remember: RIP Always, and
SalK= Killed)
18
Q
Name two recombinant vaccines.
A
Hepatitis B virus and human papilloma virus vaccines
19
Q
What is the antigen that is present in the hepatitis B virus vaccine?
A
Recombinant hepatitis B surface antigen
20
Q
Which human papillomavirus types does the human papillomavirus vaccine protect
against?
A
Types 6, 11, 16, and 18; the types most likely to cause cervical cancer and genital
warts
21
Q
What is the only live, attenuated vaccine that can be given to HIV-positive
individuals?
A
MMR (measles, mumps, rubella)
22
Q
All DNA viruses contain double-stranded DNA, except for which family?
A
Parvoviridae, which has single-stranded DNA (remember: part-of-a-virus)
23
Q
Which three DNA viruses contain nonlinear DNA?
A
Papilloma, polyoma, and hepadna viruses, which contain circular DNA
24
Q
All RNA viruses contain single-stranded RNA, except for which family?
A
Reoviridae (remember: all are single-strand RNA except “repeatovirus” [reovirus]
is double-stranded RNA])
25
Purified nucleic acids from which viruses are considered infectious?
Most double-stranded DNA viruses and positive-strand single-stranded RNA
viruses
26
Why are negative-strand single-stranded RNA and double-stranded RNA viruses
not infectious?
They require enzymes found in the complete virion to become infectious
27
The purified nucleic acids of what two double-stranded DNA viruses are not
considered infectious?
Poxviruses and hepatitis B virus; both require enzymes not found in human cells
for replication
28
Are most viruses haploid or diploid?
Most are haploid (one copy of genetic material)
29
What is the only virus that is not haploid?
Retroviruses (2 copies of single-stranded RNA)
30
With one exception, all DNA viruses replicate in what part of the host cell?
Nucleus
31
All DNA viruses replicate in the nucleus of the host cell, except for which virus?
Poxvirus
32
Do most RNA viruses replicate in the cytoplasm or the nucleus of the host cell?
Cytoplasm
33
Which two RNA viruses replicate in the host cell nucleus?
The influenza virus and retroviruses
34
What are the seven naked (nonenveloped) viruses?
```
Calicivirus, Picornavirus, Reovirus, Parvovirus, Adenovirus, Papillomavirus,
and Polyomavirus (remember: naked CPR and PAPP smear)
```
35
From what structure are most viral envelopes derived?
Plasma membrane
36
The herpesviruses acquire their envelopes from which component of the host cell?
Nuclear membrane
37
Name three enveloped DNA viruses.
Herpesviruses, hepatitis B virus, smallpox virus
38
Herpesviruses are _____ (DNA/RNA) _____ (enveloped/nucleocapsid) viruses.
DNA; enveloped
39
Hepatitis B is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
DNA; enveloped
40
Smallpox is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
DNA; enveloped
41
Name three DNA nucleocapsid viruses.
Adenovirus, papillomaviruses, parvovirus
42
Adenovirus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
DNA; nucleocapsid
43
Papillomavirus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
DNA; nucleocapsid
44
Parvovirus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
DNA; nucleocapsid
45
Influenza virus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
46
Parainfluenza is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
47
Respiratory syncytial virus is a _____ (DNA/RNA) _____
| (enveloped/nucleocapsid) virus.
RNA; enveloped
48
Measles virus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
49
Mumps virus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
50
Rubella virus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
51
Rabies is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
52
Human T-lymphotropic virus is a _____ (DNA/RNA) _____
| (enveloped/nucleocapsid) virus.
RNA; enveloped
53
HIV is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; enveloped
54
Enteroviruses are _____ (DNA/RNA) _____ (enveloped/nucleocapsid) viruses.
RNA; nucleocapsid
55
Rhinovirus is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid) virus.
RNA; nucleocapsid
56
Reovirus (rotavirus) is a _____ (DNA/RNA) _____ (enveloped/nucleocapsid)
virus.
RNA; nucleocapsid
57
Name the three types of RNA nucleocapsid viruses.
Enteroviruses, rhinovirus, and reovirus (rotavirus)
58
Name the seven DNA viruses.
```
Hepadnavirus, Herpesvirus, Adenovirus, Poxvirus, Parvovirus, Papillomavirus,
and Polyomavirus (remember the mnemonic: HHAPPPPy viruses)
```
59
All DNA viruses are linear except what three DNA viruses?
Hepadnavirus (circular, incomplete) and papillomavirus/polyomavirus (circular,
supercoiled)
60
All DNA viruses are icosahedral except which one?
Poxvirus; it is complex
61
Which DNA virus does not replicate in the nucleus?
Poxvirus; it has a DNA-dependent RNA polymerase and can replicate without nuclear enzymes
62
In general, DNA viruses are _____ (single/double) stranded, _____
(linear/circular), icosahedral, and replicate in the _____ (nucleus/cytoplasm).
Double stranded; linear; nucleus
63
Name seven medically important herpesviruses.
Herpes simplex virus type 1, herpes simplex virus type 2, varicella zoster virus,
Epstein-Barr virus, cytomegalovirus, human herpesvirus type 6, and human
herpesvirus type 8 (human herpesvirus 7 is not clinically significant)
64
Which herpesvirus most often causes oral lesions as well as keratoconjunctivitis?
Herpes simplex virus type 1
65
Which herpesvirus most often causes genital lesions in humans?
Herpes simplex virus type 2
66
Chickenpox, zoster, and shingles are caused by what DNA virus?
Varicella zoster virus
67
Which types of patients are particularly vulnerable to significant cytomegalovirus infection?
Immunosuppressed patients (especially transplant recipients) and the fetuses of infected mothers
68
Which childhood illness is caused by human herpesvirus type 6?
Roseola (exanthem subitum)
69
Which DNA virus is associated with Kaposi sarcoma?
Human herpesvirus type 8 (Kaposi’s sarcoma-associated herpesvirus)
70
To what viral family does hepatitis B virus belong?
Hepadnavirus
71
Which enzyme does hepatitis B virus have in common with retrovirus?
Reverse transcriptase
72
Adenovirus is most commonly responsible for what three conditions?
Febrile pharyngitis (sore throat), pneumonia, and conjunctivitis
73
What is the smallest DNA virus?
Parvovirus
74
What skin exanthem does parvovirus B19 cause in children?
Erythema infectiosum ("slapped-cheek" rash)
75
Parvovirus B19 causes what condition in patients with sickle cell disease?
Aplastic crisis
76
What severe complication is seen in the fetuses of pregnant women who are
exposed to parvovirus B19?
Hydrops fetalis (due to red blood cell destruction)
77
What two DNA virus families were originally categorized together as
papovavirus?
Papillomavirus and polyomavirus
78
What type of disease does papillomavirus cause?
Genital warts, cervical intraepithelial neoplasia, and cervical cancer
79
JC virus is the causative agent of what condition in HIV-positive patients?
Progressive multifocal leukoencephalopathy
80
Which viral family is responsible for smallpox, cowpox, and molluscum
contagiosum?
Poxvirus
81
What is the largest DNA virus?
Poxvirus
82
Which disease caused by a poxvirus has been eradicated but could possibly be used
in germ warfare?
Smallpox
83
Vaccinia virus causes what condition?
Cowpox ("milkmaids blisters")
84
Which is the only hepatitis-causing virus that is a DNA virus?
Hepatitis B virus
85
Name six medically important herpesviruses.
Cytomegalovirus, Herpes simplex virus types 1 and 2, Human herpesvirus type
8, Epstein-Barr virus, Varicella zoster virus (remember: get herpes in
a CHEVrolet)
86
Which herpesvirus causes gingivostomatitis, keratoconjunctivitis, temporal lobe
encephalitis, and herpes labialis?
Herpes simplex virus type 1
87
Herpes encephalitis usually affects which lobe of the brain?
The temporal lobe
88
Herpes genitalis and neonatal herpes are most commonly caused by what herpes virus?
Herpes simplex virus type 2
89
Shingles, encephalitis and pneumonia can be caused by which herpesvirus?
Varicella zoster virus
90
Epstein-Barr virus causes what conditions?
Infectious mononucleosis, Burkitts lymphoma and nasopharyngeal carcinoma
91
Cytomegalovirus causes what conditions?
Congenital infection, mononucleosis, and pneumonia
92
What is the most likely etiology for a mononucleosis-like presentation that is
monospot test negative?
Cytomegalovirus
93
Human herpesvirus type 8 can cause what disease in HIV-positive patients?
Kaposi sarcoma
94
What is the primary route of transmission of herpes simplex virus type 1?
Respiratory secretions and saliva
95
How is herpes simplex virus type 2 primarily transmitted?
Via sexual contact and perinatally
96
How is varicella zoster virus transmitted?
Respiratory secretions
97
What are the modes of cytomegalovirus transmission?
Congenital, transfusion, sexual contact, saliva, urine, and organ transplantation
98
Human herpesvirus type 8 is primarily transmitted via what route?
Sexual contact
99
What histologic finding is characteristic of cells infected with cytomegalovirus?
"Owls eye" intranuclear inclusions
100
How is Epstein-Barr virus transmitted?
Respiratory secretions and saliva
101
Where does varicella zoster virus remain dormant in the body after primary
infection?
In the dorsal root and trigeminal ganglia
102
Describe the clinical presentation of human herpesvirus type 6 infection.
Roseola: high fevers followed by a diffuse macular rash; human herpesvirus type 6
is one of the most common causes of febrile seizures in children
103
What is the Tzanck test?
A test to detect multinucleated giant cells in opened skin vesicles of herpes simplex
virus type 1 and 2 and varicella zoster virus
104
HSV-infected cells contain inclusion bodies known as what?
Cowdry A intranuclear inclusions
105
Which herpesvirus is the most common cause of mononucleosis?
Epstein-Barr virus
106
Epstein-Barr virus causes mononucleosis by infecting which cells?
B cells
107
A college student presents to the emergency department with fever,
hepatosplenomegaly, pharyngitis and lymphadenopathy (especially posterior
cervical nodes). Which viral infection should be suspected?
Epstein-Barr virus can cause mononucleosis, also known as the "kissing disease"
because its peak incidence is 15-20 years old (peak "kissing years"); transmission
is through saliva
108
What laboratory test can be used to diagnose mononucleosis?
Monospot test: heterophil antibodies detected by agglutination of sheep red blood cells
109
A complete blood count of a patient with infectious mononucleosis would show
what abnormalities?
Atypical lymphocytes (circulating cytotoxic T cells)
110
Epstein-Barr virus is associated with the development of which three types of
malignancy?
Hodgkins and endemic Burkitts lymphoma and nasopharyngeal carcinoma
111
What vaccines exist against poliovirus?
Salk (inactivated polio vaccine) and Sabin (oral polio vaccine)
112
Which two picornaviruses commonly cause aseptic meningitis?
Echovirus and coxsackievirus
113
Which two RNA viruses cause the common cold?
Rhinovirus and coronavirus
114
Aseptic meningitis; myocarditis; herpangina; and hand, foot, and mouth disease are
caused by which picornavirus?
Coxsackieviruses
115
Name a medically important calicivirus.
Norwalk virus
116
Norwalk virus causes what condition?
Viral gastroenteritis
117
Rotavirus belongs to which viral family?
Reoviruses
118
Reovirus causes what condition?
Colorado tick fever
119
The structure of the genome of reovirus is unique among RNA viruses in what
respect?
It has double-stranded RNA with 10-12 strands, whereas all other RNA viruses are
single stranded
120
Flaviviruses are responsible for what five diseases?
Hepatitis C virus, yellow fever, dengue, St. Louis encephalitis, and West Nile virus
121
Togaviruses cause what three diseases?
Rubella (German measles), Eastern equine encephalitis, and Western equine
encephalitis
122
Name two RNA viruses that have reverse transcriptase.
HIV (a retrovirus), and human T-lymphotropic virus
123
Human T-lymphotropic virus causes what disease?
T-lymphocyte leukemia
124
Coronaviruses are the causative agents of what two diseases?
The common cold and severe acute respiratory syndrome (SARS)
125
Which medically important RNA virus belongs to the orthomyxovirus family?
Influenza
126
Name four medically important paramyxoviruses.
Parainfluenza, Respiratory syncytial virus, Measles (rubeola), and Mumps;
remember: PaRaMyxoviruses
127
What disease does parainfluenza virus cause?
Croup
128
What disease does respiratory syncytial virus cause in babies?
Bronchiolitis
129
Rabies virus is what type of virus?
Rhabdovirus
130
Filoviruses are the causative agents of what two diseases?
Ebola hemorrhagic fever and Marburg hemorrhagic fever; both are frequently fatal
131
Arenaviruses are the causative agents of what two diseases?
Lymphocytic choriomeningitis and Lassa fever encephalitis
132
Bunyaviruses are the causative agents of what four diseases?
California encephalitis, Sandfly/Rift Valley fevers, Crimean-Congo hemorrhagic
fever and hantavirus
133
Hepatitis D virus belongs to which viral family?
Deltavirus
134
The viruses that cause viral hepatitis A-E in humans belong to which families?
Picornavirus (hepatitis A), hepadnavirus (hepatitis B), flavivirus (hepatitis C),
deltavirus (hepatitis D), hepevirus (hepatitis E)
135
Name six viral families that are single-strand, positive-sense, linear RNA viruses
with icosahedral capsids.
Picornavirus, hepevirus, calicivirus, flavivirus, togavirus, and retrovirus
136
Name the viral family that is made up of double-stranded RNA viruses with a
double icosahedral capsid.
Reovirus
137
All negative-sense RNA viruses have what type of capsid?
Helical
138
Which clinically significant virus has a segmented linear RNA?
Influenza (an orthomyxovirus)
139
What are the three viral families with circular RNA?
Arenaviruses, bunyaviruses, and deltavirus
140
What is the only positive-sense RNA virus with a helical capsid?
Coronavirus
141
True or False? All helical viruses are enveloped.
True
142
Which diseases are caused by arboviruses?
Yellow fever, dengue, St. Louis encephalitis, West Nile virus, Eastern equine
encephalitis and Western equine encephalitis, California encephalitis, Crimean-
Congo hemorrhagic fever
143
Name the four families of RNA viruses that have no envelope.
Reoviruses, picornaviruses, hepevirus and caliciviruses
144
What must a negative-stranded DNA virus do to replicate within a human cell?
Transcribe its negative strand to a positive strand; it does this by carrying an RNA-
dependent RNA polymerase
145
Name the six negative-stranded virus families.
```
Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthomyxoviruses, Filoviruses,
and Rhabdoviruses (remember: Always Bring Polymerase Or Fail Replication)
```
146
All segmented viruses are ____ (RNA/DNA) viruses.
RNA
147
Name four segmented RNA viruses.
Bunyaviruses, Orthomyxoviruses (influenza), Arenaviruses, and Reoviruses
(remember: BOAR)
148
How many segments of RNA make up the influenza virus genome?
Eight
149
The reassortment of influenza virus RNA segments results in antigenic _____
(shift/drift) and is a cause of _____ (pandemics/epidemics).
Shift; pandemics
150
What five RNA viruses are picornaviruses?
Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, and Hepatitis A virus
(remember: PERCH on a "peak" = Pico)
151
Picornaviruses (except rhinovirus and hepatitis A virus) can cause what condition
in humans?
Aseptic meningitis
152
Picornaviruses are (small/large) _____, (RNA/DNA) _____ viruses.
Small, RNA (remember: PicoRNAvirus = RNA virus)
153
What type of virus is rhinovirus?
A nonenveloped RNA virus that belongs to the picornavirus family
154
Why are humans susceptible to multiple recurrent infections with rhinovirus
causing cold-like symptoms?
Because there are more than 100 serologic types of rhinovirus
155
Yellow fever is caused by a virus that belongs to what viral family?
Flavivirus, which is an arbovirus (flavi = yellow)
156
How is yellow fever transmitted?
By Aedes mosquitoes
157
A 30-year-old man presents to the emergency room with a high fever, black
vomitus, and a yellow discoloration to his skin. What is the most likely etiology?
Yellow fever
158
What histologic finding on liver biopsy is seen in patients with yellow fever?
Councilman bodies (acidophilic inclusion bodies)
159
Globally, what is the most important cause of infantile gastroenteritis?
Rotavirus
160
During what season is rotavirus the major cause of acute diarrhea in the United
States?
Winter, although a new vaccine is significantly reducing cases of rotavirus
161
What is the pathophysiology of the diarrhea caused by rotavirus?
Atrophy and destruction of intestinal villi lead to decreased absorption of sodium
and water; remember: ROTA = Right Out The Anus
162
In what settings are rotavirus diarrhea commonly seen?
Daycare centers and kindergartens
163
Influenza virus is _____ (enveloped/nonenveloped), with _____-_____ (single-
stranded/double-stranded), _____ (segmented/nonsegmented) RNA.
Enveloped; single-stranded; segmented
164
Name the two major antigens of the influenza virus.
Hemagglutinin and neuraminidase
165
If influenza results in fatal illness, which complication is usually responsible?
Pneumonia caused by bacterial superinfection
166
What is the major mode of protection against influenza virus?
Killed virus vaccine; the vaccine is reformulated each year
167
What are the functions of hemagglutinin and neuraminidase?
Hemagglutinin promotes viral entry and neuraminidase promotes the release of
viral progeny
168
The recombination of human flu A virus with swine flu A virus is an example of
what?
Genetic shift, the reassortment of viral genome, which can cause worldwide
pandemics
169
Random mutations leading to minor genetic changes in the human flu A virus is an
example of what?
Genetic drift (antigenic drift)
170
Genetic shift causes (epidemics/pandemics) _____ while genetic drift causes
(epidemics/pandemics) _____.
Pandemics, epidemics; remember: Sudden Shift is more deadly than graDual Drift
171
An unvaccinated 4-year-old boy presents with fever, lymphadenopathy, arthralgias
and a fine truncal rash. The rash persists for only 3 days. Which viral infection
should be suspected?
Rubella
172
Rubella is a relatively benign illness in most cases, but when can serious sequelae
result?
When it infects fetuses (it is one of the T0RCH infections)
173
What diseases are caused by paramyxoviruses?
Mumps, measles, croup and respiratory syncytial virus bronchiolitis
174
Paramyxoviruses cause disease predominantly in what age group?
Children
175
What is the typical clinical presentation of croup?
A seal-like barking cough
176
What surface protein is common to all paramyxoviruses? What is its role?
```
Surface F (fusion) protein, which causes respiratory epithelial cells to fuse and
form multinucleated cells
```
177
Injections of which monoclonal antibody are given to children at high risk of
severe respiratory syncytial virus bronchiolitis?
Palivizumab
178
Describe the progression of disease in rabies.
It begins with fever and malaise, develops into agitation, hydrophobia,
photophobia, and then paralysis, coma, and death
179
How does rabies virus invade the central nervous system?
By migrating in a retrograde fashion up the nerve axons
180
What animal bites are most likely to result in rabies infection in the United States?
Bat, raccoon, and skunk bites
181
What is the importance of postexposure vaccination in rabies?
The disease is universally fatal after symptoms have developed
182
What are arboviruses?
Viruses transmitted by arthropods (remember: ARBOvirus: ARthropod-BOrne
virus)
183
Arboviruses include members of which viral families?
Flavivirus, Togavirus, and Bunyavirus (remember: Fever Transmitted by Bites)
184
The hepatitis A virus is primarily transmitted via what route?
The fecal-oral route
185
The hepatitis E virus is primarily transmitted via what route?
The enteric route (causing water-borne epidemics)
186
The clinical course of hepatitis E infection resembles that of what other hepatitis
virus?
Hepatitis A
187
How is the hepatitis E virus different from the hepatitis A virus?
The hepatitis E virus can cause waterborne epidemics and has a high mortality rate
among pregnant women (remember: Hep E: Enteric, Expectant
mothers, Epidemics)
188
How does the number of people with serologic evidence of prior hepatitis A
infection compare to the number who have had clinically significant infection?
Most infections are clinically insignificant (remember:
| Hep A: Asymptomatic, Acute, Alone [no carriers])
189
Does hepatitis A virus have a short or long incubation period?
Short (3 weeks); there are no chronic carriers of the infection
190
How is the hepatitis B virus transmitted?
By parenteral, sexual, or maternal-fetal routes (remember: Hepatitis B: Blood
borne)
191
Which hepatitis virus has a reverse transcription capability?
Hepatitis B virus; reverse transcription occurs (DNA from an RNA
intermediate) but the virion enzyme is a DNA-dependent DNA polymerase
