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Viruses Flashcards

1
Q

What is HHV-6 known for?

A

Infects T cells and causes roseola

Only a problem in immunocompromised patients.

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2
Q

What disease is associated with HHV-8?

A

Kaposi’s sarcoma virus (KSHV)

Before HIV disease, only known to cause disease in men of Mediterranean descent and chemotherapy patients.

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3
Q

What is the most common cause of encephalitis?

A

HSV-1

High fatality rate in untreated patients (70%) and survival often leads to permanent neurological disorders.

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4
Q

How is neonatal herpes transmitted?

A

In utero, during birth, after birth

High fatality rate if untreated (50%).

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5
Q

What are the main components of the immune response against herpesviruses?

A

IgG, IgA, IgM and CTL responses

Immune response is not sterilizing.

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6
Q

What is the role of the α47 protein in herpesvirus infections?

A

Retains class I molecules in the cytoplasm

This impairs the immune response.

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7
Q

What is the significance of PCR in laboratory diagnosis of herpesvirus diseases?

A

Used for systemic or encephalitic disease

PCR is the method of choice as virus isolation is slow.

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8
Q

What is the prevalence of HSV-1 in adults?

A

Most adults are seropositive

Only a small proportion have recrudescence.

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9
Q

What is the main characteristic of HSV-2?

A

Most commonly acquired by young adults

It is a sexually transmitted disease.

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10
Q

What is the drug of choice for herpesvirus treatment?

A

Acyclovir

It is a nucleoside analog phosphorylated by HSV thymidine kinase.

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11
Q

What are the symptoms of oropharyngeal disease caused by herpes simplex viruses?

A

Fever, vesicular and ulcerative lesions, edema, gingivostomatitis, lymphadenopathy, malaise

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12
Q

What is the typical latency site for HSV-1?

A

Trigeminal ganglia

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13
Q

What are the two species of herpes simplex viruses?

A

HSV-1 and HSV-2

Highly similar genomes, but distinct.

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14
Q

What is the primary transmission route for varicella (chickenpox)?

A

Respiratory transmission

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15
Q

What is a common complication of varicella in immunocompromised patients?

A

Ocular infections can lead to impaired vision

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16
Q

What is the incubation period for infectious mononucleosis caused by Epstein-Barr virus?

A

Up to 50 days

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17
Q

What is the primary target of the Epstein-Barr virus?

A

B cells

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18
Q

What is the largest genome among human herpesviruses?

A

Cytomegalovirus (CMV)

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19
Q

What is a key feature of herpesviruses?

A

Establish latency and lifelong persistence

They can cause lytic, persistent, latent, and immortalizing infections.

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20
Q

What defines the structure of herpesviruses?

A

Spherical icosahedron, double-stranded DNA, enveloped

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21
Q

What is the effect of gC and gE proteins in herpes simplex viruses?

A

gC binds complement C3b and gE is an Fc receptor for IgG

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22
Q

Fill in the blank: Herpes simplex virus type 1 primarily causes _______.

A

Oropharyngeal sores

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23
Q

Fill in the blank: Herpes simplex virus type 2 primarily affects _______.

A

Genitalia

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24
Q

True or False: There is a vaccine available for herpes simplex viruses.

A

False

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25
What is the diameter size range of viruses?
20 to 350 nm
26
What are the main components of a virus?
* Genome * Capsid * Envelope
27
Define a virus.
Smallest infectious agents
28
What type of agents are viruses classified as?
Obligate intracellular agents
29
What is a virus capsid?
The protein coat that protects the viral genome
30
What are capsomers?
Repeating units that make up the capsid
31
What is the function of glycoproteins in a virus?
Facilitates virus attachment to host cells
32
What are the two main forms of virus morphology?
* Helical forms * Icosahedron form
33
What is the role of the virus envelope?
Surrounds the nucleocapsid and carries glycoprotein projections
34
What types of nucleic acids can a virus have?
* RNA * DNA
35
Fill in the blank: Viruses can exist in _______ or _______ strands.
[single] or [double] strands
36
What are the possible forms of a virus genome?
* Linear * Circular * Single piece * Segmented
37
True or False: Viruses are living things while inside a host.
True
38
What classification system places viruses into one of 7 groups?
Baltimore classification system
39
What is the process of naming viruses and placing them into a taxonomic system called?
Virus classification
40
What criteria are used for virus classification?
* Morphology * Nucleic acid type * Mode of replication * Host organisms * Pathogenicity * Ecological criteria * Physico-chemical properties
41
How many DNA families are recognized in humans?
7
42
How many RNA families are found in humans?
14
43
What are the properties of viruses?
* Filterable agents * Highly host specific * Susceptible to physical and chemical agents * Highly susceptible to anti-viral agents * Best preserved at sub-zero temperatures * Freeze-drying preserves them better
44
What is the 'live wire' of virus activities?
Virus genome
45
What are the examples of the Adenoviridae family?
* Human Adenovirus (several serotypes)
46
What is the genus of the Hepadnaviridae family?
Hepadnavirus
47
Which virus is associated with the Herpesviridae family?
* Herpes simplex virus * Varicella virus * Cytomegalovirus * Epstein-Barr virus
48
What are the genera in the Papovaviridae family?
* Papilloma * Polyoma
49
What is a common virus in the Parvoviridae family?
B19 virus
50
What are the genera in the Poxviridae family?
* Orthopox * Suispox * Avipox * Molluscipox
51
What are the two main schemes used for virus classification?
Baltimore classification system and International Committee on Taxonomy of viruses
52
How many groups does the Baltimore classification system place viruses into?
7 groups
53
What are the taxonomic levels of the International Committee on Taxonomy of viruses?
VIRALE (order), VIRIDAE (family), VIRIAE (subfamily), VIRUS (genus, species, etc.)
54
How many DNA families are recognized in humans?
7 DNA Families
55
How many RNA families are found in humans?
14 RNA Families
56
What is the virus genome described as?
The live wire of virus activities
57
What types of nucleic acid can a virus genome contain?
RNA or DNA
58
What are the possible forms of virus genomes?
* Single or double strands * Linear or circular forms * Single piece or segmented forms
59
What is the diameter size range of viruses?
20 to 350 nm
60
What are the major components of a virus?
* Genome * Capsid * Envelope
61
What is a virus defined as?
An obligate intracellular parasite
62
What is a virion?
The infective form of a virus when present outside of cells
63
What is the function of the capsid?
* Protects the viral genome * Facilitates virus attachment to host cells * Determines virus morphology
64
What are the two main forms of virus morphology?
* Helical forms * Icosahedron form
65
What is the envelope of a virus made of?
Lipid bilayer around the capsid
66
What makes enveloped viruses vulnerable to inactivation?
Presence of the lipid bilayer
67
From where does the viral envelope originate?
Host cell's plasma membrane
68
Name a DNA virus family and an example.
Adenoviridae - Human Adenovirus (several serotypes)
69
Name a RNA virus family and an example.
Arenaviridae - Lassa virus
70
What are the three types of virus culture?
* Primary cell culture * Diploid cell culture * Continuous cell lines
71
What are the properties of viruses?
* Filterable agents * Highly host specific * Susceptible to physical and chemical agents * Highly susceptible to anti-viral agents
72
Fill in the blank: Some viruses do not possess envelopes. These are referred to as _______ viruses.
nonenveloped
73
What is the process of naming viruses and placement into a taxonomic system called?
Virus classification
74
Currently, how many viruses have been described and classified into how many families?
Over 4000 viruses classified into 71 families
75
What are the two broad categories of viruses based on their genome?
* DNA viruses * RNA viruses
76
True or False: Viruses exhibit enormous diversity compared with plants and animals.
True
77
What are the two ways influenza viruses evolve?
Antigenic drift (Ad) and Antigenic shift (As) ## Footnote Changes by Ad occur all the time, while As happen only occasionally.
78
What is the primary method used in lab-based influenza surveillance?
Reverse genetics ## Footnote This method allows the production of infectious influenza virus from cDNA.
79
Name the two classes of drugs used to treat influenza.
* M2-Inhibitors * NA-inhibitors ## Footnote Examples include Amantadine, Rimantadine, Oseltamivir (Tamiflu), and Zanamivir (Relenza).
80
What is the primary means of influenza prevention?
Activated viral vaccine ## Footnote Control by immunization is difficult due to evolving viruses.
81
What are the major components of pandemic preparedness?
* A surveillance network for human and animal influenza * A targeted influenza vaccination program * Ensuring an adequate system for alert, response, and disaster management ## Footnote These components help strengthen the capacity to respond to yearly epidemics.
82
What is antigenic drift?
Small gradual point mutations in HA and NA genes ## Footnote This results in new virus strains not recognized by antibodies to earlier strains.
83
What is antigenic shift?
Drastic changes in the sequence of HA/NA ## Footnote Involves genetic re-assortment between human and animal virus genomes.
84
What are the three conditions that define a global influenza pandemic?
* A new subtype of influenza A virus * Virus causes serious illness in humans * Virus spreads easily from person to person in a sustained manner
85
What was the estimated death toll of the 1918 influenza pandemic?
40 – 50 million deaths worldwide ## Footnote This pandemic is regarded as the highest infectious disease catastrophe on record.
86
What are the major clinical manifestations of influenza?
* Fever * General body pain * Sore throat * Non-productive cough * Headache * Myalgia * Malaise ## Footnote Recovery in uncomplicated cases takes about a week.
87
What are the complications associated with influenza?
* Pneumonia * Bronchitis * Bronchiolitis ## Footnote Pneumonia is a major cause of death, primarily viral or secondary bacterial.
88
What are the two lineages of influenza B viruses currently circulating?
* B/Yamagata * B/Victoria ## Footnote Influenza B viruses are not divided into subtypes but can be further broken down into lineages.
89
What are the four types of influenza viruses?
* Influenza A * Influenza B * Influenza C * Influenza D ## Footnote Only influenza A viruses are responsible for sporadic pandemics.
90
What is the role of hemagglutinin (HA) in influenza viruses?
Mediates attachment to ciliated respiratory epithelium ## Footnote HA occurs as a dimer, consisting of HA1 and HA2.
91
What is the incubation period for influenza?
1-4 days ## Footnote Spread occurs via airborne droplets and direct contact with infected surfaces.
92
What is the naming convention for influenza viruses?
Includes antigenic type, host of origin, geographical origin, strain number, year of isolation, and HA/NA antigen description ## Footnote For example, A/duck/Alberta/35/76 (H1N1) indicates a virus from duck origin.
93
True or False: Influenza B viruses can infect a wide range of hosts.
False ## Footnote Influenza B viruses infect only humans, while influenza A viruses can infect various species.
94
What is the primary viral composition of influenza viruses?
RNA (1%), protein (73%), lipid (20%), carbohydrate (6%) ## Footnote Influenza viruses have a segmented, negative-sense RNA genome.
95
What are the members of the family that includes Isavirus, Quaranjavirus, and Thogotovirus?
C and D ## Footnote These are classifications within the virus family that includes various influenza viruses.
96
Which influenza virus has long been the cause of pandemic infections in humans?
Influenza A virus ## Footnote Influenza A virus is known for its significant impact on human health through pandemics.
97
What are the key roles of the viral envelope proteins of influenza A virus?
Attachment to host receptors, pathogenicity, release of progeny virus ## Footnote These functions are critical for the virus's life cycle and its ability to infect hosts.
98
What genes encode the viral envelope proteins of influenza A virus?
Hemagglutinin (HA) and neuraminidase (NA) ## Footnote These proteins are crucial for the virus's ability to infect and spread.
99
How many influenza A virus subtypes can be produced?
198 subtypes ## Footnote This is based on the combination of 18 HA and 11 NA genes.
100
What percentage of influenza A virus subtypes have been reported to infect humans?
7% ## Footnote This indicates a limited number of subtypes that can cross the species barrier to infect humans.
101
What is the function of the HA gene in influenza A virus?
Binds to the host receptor protein ## Footnote This is essential for the virus to enter and infect the host cell.
102
What role does the NA gene play in the life cycle of influenza A virus?
Receptor destroying enzyme involved in release of the virus from the host cell ## Footnote This function is critical for the spread of the virus to new cells.
103
What are the targets of antiviral drugs in influenza A virus?
HA and NA proteins ## Footnote Targeting these proteins can inhibit the virus's ability to infect and spread.
104
True or False: The HA and NA genes are responsible for the immunogenic response in hosts.
True ## Footnote The antibodies produced against these proteins are key to the immune response.
105
What does IPT stand for?
Isoniazid Preventive Treatment
106
What is the purpose of IPT?
To prevent the development of active TB disease in HIV positive individuals
107
True or False: TB is frequently associated with HIV.
True
108
What must be excluded before commencing a patient on IPT?
Active TB
109
What is the daily dose of Isoniazid for preventing latent TB infection?
300 mg
110
What are the benefits of combined use of IPT and ART?
TB prevention and mortality benefits
111
Who should be counselled and motivated to adhere to IPT?
HIV positive individuals
112
What is the recommended dose of Cotrimoxazole for adults?
960 mg daily
113
Fill in the blank: Common side effects associated with CPT include _______.
skin eruptions, nephritis, hepatitis, anaemia, hyperkalaemia
114
What should a health worker verify before starting a client on CPT?
HIV status
115
Cotrimoxazole prophylaxis is recommended for which groups?
Infants, children, and adolescents with HIV
116
What is the rationale behind Cotrimoxazole Preventive Therapy?
To prevent AIDS-associated opportunistic diseases and reduce HIV-associated mortality
117
What is the relationship between HIV and opportunistic infections?
HIV depresses immunity, increasing predisposition to OIs
118
What are the two main strategies for preventing opportunistic infections?
* Cotrimoxazole preventive treatment (CPT) * Isoniazid Preventive Treatment (IPT)
119
What percentage of new HIV infections in Nigeria is attributed to sex workers, men who have sex with men, and people who inject drugs?
32%
120
What is the HIV prevalence among adults in Nigeria?
2.8%
121
What is the estimated percentage of people living with HIV in Nigeria that are women?
58%
122
What are the modes of HIV transmission?
* Sexual contacts * Mother to child transmission (MTCT) * Blood contacts
123
What is the risk of percutaneous injuries in the healthcare setting for HIV transmission?
0.3%
124
What are the two main classes of antiretroviral drugs?
* Nucleoside analogues reverse transcriptase inhibitors * Non-nucleoside analogue reverse transcriptase inhibitors
125
What is the normal CD4+ count range?
500-1600 cells/mm3
126
What is the goal of therapy (HAART) in terms of viral load?
To lower viral load below detectable level
127
What is the significance of viral load assays?
It measures viral particles/copies in mL of blood
128
What can significantly reduce the risk of mother-to-child transmission of HIV?
Effective PMTCT programs
129
What factors contribute to the progression of HIV infection?
* High viral load * Low CD4 count * Increasing clinical symptoms
130
What is the main route of transmission for HIV worldwide?
Heterosexual transmission
131
What is the role of antiretroviral therapy in HIV disease progression?
Prevents the progression to symptomatic disease and AIDS
132
True or False: HIV is a chronic viral infection with no known cure.
True
133
What is the relationship between CD4+ count and immune suppression in HIV infection?
Lower CD4+ count means decreasing immunity
134
What is the impact of HIV on organ systems?
Direct infection can occur in the brain, gut, and heart
135
What is the natural history of HIV infection characterized by?
Immune suppression due to HIV attacking white blood cells
136
What indicates a high viral load in HIV infection?
Number of copies of HIV in the blood
137
What does a low CD4 count signify in HIV disease progression?
Decreasing immunity
138
What are clinical symptoms of HIV infection?
Opportunistic infections
139
What are the key measures for progression of HIV disease?
* CD4+ count * Degree of immune suppression * Viral load
140
What happens to the body's ability to fight infections over time with HIV?
It is lost, leading to opportunistic infections
141
List the stages of HIV infection.
* Seroconversion * Asymptomatic * Symptomatic * AIDS
142
What is the primary receptor that HIV binds to?
CD4
143
What are the coreceptors for HIV?
* CCR5 (R5 HIV) * CXCR4 (X4 HIV)
144
What is the function of the p24 protein in HIV?
Most abundant viral protein, a biomarker for early diagnosis
145
How are retroviruses classified?
* Simple retroviruses * Complex retroviruses
146
What are oncoviruses?
Retroviruses that can induce cancer
147
What are the three subfamilies of retroviruses?
* Oncoviruses * Lentiviruses * Spumaviruses
148
True or False: Lentiviruses like HIV have a low virus load.
False
149
What is the role of reverse transcriptase in HIV?
Transcribes RNA into DNA
150
What type of cells does HIV primarily infect?
CD4+ lymphocytes, monocytes, macrophages, and dendritic cells
151
What is HIV infection considered globally?
A pandemic
152
Which region has the highest HIV epidemic severity?
Sub-Saharan Africa
153
What is AIDS an acronym for?
Acquired Immune Deficiency Syndrome
154
What does HIV-1 and HIV-2 refer to?
* HIV-1: more common worldwide * HIV-2: found in West Africa, less pathogenic
155
What are the primary routes of HIV transmission?
Same routes for both HIV-1 and HIV-2
156
Fill in the blank: HIV is a type of _______.
Retrovirus
157
What is the structure of an HIV virus particle?
Spherical, approximately 1/10,000 mm in diameter
158
What is the role of the viral enzymes present in HIV?
* Protease * Reverse transcriptase * Integrase
159
What does a low CD4+ count indicate in terms of immune function?
Increased immune suppression
160
What happens to the immune system as HIV progresses to AIDS?
Weakens and leads to opportunistic infections

Microbiology (5 decks)

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