Virology Flashcards
1
Q
What are the components of a Virion?
A
- Genome: DNA or RNA (Instructions to clone itself)
- Protein coat: Protection, Facilitates attachment, and Antigens
- May contain enzymes needed for transcription (e.g. polymerase)
- No energy source
- No metabolic processes
2
Q
What are viral spikes or glycoproteins?
A
- Protein (or protein + glycogen) that are antigens
- Responsible for different viral serotypes (viral subcategories)
3
Q
What is the difference between a naked and an enveloped virus?
A
- Enveloped has outer lipid bilayer
- Naked survive better in the environment (i.e. not as sensitive to heat, drying, alcohol, etc)
4
Q
What is the difference between positive and negative stranded viral RNA?
A
- Positive stranded can immediately be translated into protein.
- Negative stranded must be transcribed into a positive RNA strand prior to being translated. Virus can have it own enzyme to transcribe negative stranded to positive stranded
5
Q
What is unique about retroviruses?
A
Even though they are positive stranded RNA virus they cannot be immediately translated. They use virion reverse transcriptase to copy RNA to DNA, which is then incorporated into the host genome
6
Q
What are the (+) RNA Naked viruses?
A
- Calici (Norwalk)
- Hep E
- Reov (Rotavirus) Double Stranded
- Picorna (Polio, Echo, Rhino, Cox, Hep A)
7
Q
What are the (+) RNA Enveloped viruses?
A
- Corona (viral pharyngitis)
- Retro (HIV) Reverse- transcribed
- Flavi (Westnile, Hep. C, Dengue, Yellow fever)
- Toga (Rubella, Alpha, Rubi)
8
Q
What are the (-) RNA enveloped viruses?
A
- Bunya
- Paramyxo (Mumps and Morbilli –> Measles)
- Orthomyxo (Influenza A, B, C)
- Rhabdo (Rabies)
9
Q
What are the Naked DNA viruses?
A
- Parvo (B19 –> Fifths Disease) Single Stranded
- Adeno
- Papilloma
10
Q
What are the Enveloped DNA viruses?
A
- Hepadna
- Herpos (Varicella + Herpes Zoster, Herp 6 or 7 –> Roseola)
- Pox (Small pox)
11
Q
What is unique about DNA viruses?
A
- DNA must first be transcribed into RNA, then translated into proteins (They make mRNA using host RNA polymerase)
- Positive strand is read and transcribed into mRNA
12
Q
What is unique about a Prion?
A
- Composed entirely of protein
- No DNA or RNA
- Disrupts neuron function by converting normal cells into –> B-pleated sheets
13
Q
Describe Viral Transmission
A
1-Attachment to host cell: Virion surface proteins attach to receptor proteins on the cell surface
2-Penetration/Entry: Naked viruses engulfed by vesicle
Enveloped viruses undergo fusion
3-Uncoating to release the genome: Low vesicle pH uncoats virion. Rupture or fusion SEE PICTURE
4-Gene expression: Virus specific mRNA synthesis
Synthesis of viral proteins
5-Genome replication: DNA viruses replicate in the nucleus using host cell DNA-dependent RNA polymerase
Exception = poxviruses – cytoplasm
RNA viruses replicate in the cytoplasm
6-Assembly:
Viral nucleic acid packaged within capsid proteins
Rupture of cell membrane releasing assembled virions (usually naked viruses)
OR
Budding process (enveloped viruses)
14
Q
What happens to host cells when they become infected with a virus?
A
- Death: Macromolecular synthesis inhibited
- Fusion of cells to form multinucleated cells: Due to cell membrane changes
- Malignant transformation: Unrestrained growth, Prolonged survival, Morphologic changes
- No effect
15
Q
What are the stages of a viral infection?
A
- Incubation: Asymptomatic
- Prodromal: Non-specific symptoms
- Specific-illness: Characteristic symptoms and signs
- Recovery: Illness wanes
- Persistence (sometimes): Chronic carrier state, latent infection
16
Q
List the Viral Infection Diagnostic procedures.
A
- Cell culture – presumptive diagnosis
- Definitive identification – uses known antibody with various tests
- Microscopic identification
- Serologic procedures
- Viral antigens
- Viral nucleic acids
17
Q
Define Cell culture diagnosis.
A
Virus growth produces characteristic cytopathic effect (CPE)
18
Q
Describe serologic procedures.
A
Antibody titer in acute-phase and convalescent-phase (10-14 days later) compared (4-fold higher = infected)
19
Q
What are the different types of vaccination immunity
A
1) Active immunity
- Attenuated live virus – greater, longer lasting protection
- Killed virus
- Subunit vaccines – contain purified viral proteins
2) Passive immunity
- Preformed antibody administered in immune globulins
3) Herd immunity – “community immunity”
20
Q
What are some challenges that arise with viral disease control?
A
- Difficult to obtain selective toxicity against the virus since replication so closely involved with normal synthetic processes of the cell
- Extensive viral replication occurs during the incubation period
- Drug-resistant viral mutants
21
Q
What are the respiratory illnesses?
A
- Common cold (Rhinoviruses)
- Viral pharyngitis
- Influenza
22
Q
Common Cold Infectious agent…
A
- Rhinoviruses (30-50% case): Picornavirus family
- Naked (+) RNA
23
Q
Common Cold transmission…
A
- Hosts: humans and chimps
- Entry point: URT
- Droplets (direct & indirect)
- Peaks: early fall or spring
24
Q
Common Cold Signs/symptoms…
A
- Incubation: 2-4 days
- Duration: 1 week
- sneezing, nasal discharge, sore throat, cough, headache
25
Viral pharyngitis infectious agents...
Multiple!!... Coronavirus
26
Viral pharyngitis signs and symptoms...
- Headache, malaise, +/- fever, sore throat
| - Nasal congestion, coryza, hoarseness, sinus discomfort/tenderness, ear pain, cough
27
Influenza infectious agents...
- Influenza A, B, C: Orthomyxovirus family
- Enveloped (–) RNA
- 2 glycoproteins
- Hemagglutinin (H1, H2, H3)
- Neuraminidase (N1, N2)
28
Describe antigenic shift vs drift
Drift: mutations
Shift: animal --> human… causes re-assortment of genome segments (big change!!) (H1N1)
29
Influenza transmission...
- Host: Humans
- Influenza A: mammals and birds
- Influenza B: seals
- Influenza C: pigs, dogs
- Entry point: respiratory tract
- Direct droplet spread
- Peak: winter months
30
Influenza signs and symptoms...
- Incubation: 2 days
- Duration: acute phase 3-5 days. Normal in 2-6 weeks
- Abrupt onset: FACTS
- F - fever
- A - aches (aka myalgias)
- C - chills
- T - tiredness
- S - sudden onset
- 6-12 hrs later respiratory signs (dry, nonproductive cough)
31
Influenza prevention...
Antivirals
- Neuraminidase inhibitors: block the enzyme so it can’t release/spread/infect
- Viral protein M2 inhibitor: block uncoating/assembly
Vaccines
- Killed (inactivated): virions/split subunits made of hemagglutinin antigens
- Live attenuated: antibodies form 2 weeks after vaccination
32
Influenza complications...
- Pneumonia
- Bacterial superinfection
- Reye’s syndrome
33
What are the Exanthem viruses?
- Varicella (Chickenpox)
- Herpes zoster (Shingles)
- Measles
- Roseola
- Rubella
- Fifth disease
34
Varicella (Chickenpox) infectious agents...
- Varicella zoster virus: Herpesvirus family
- Enveloped DNA
- Single serotype
35
Varicella (Chickenpox) transmission...
- Host: humans
- Respiratory droplets and direct contact w/lesions
- Mucosa of URT
- blood --> skin
- Sensory neurons: travels to dorsal root ganglia then becomes latent
36
Varicella (Chickenpox) signs and symptoms...
- Incubation: 14-21 days
- Prodrome: fever & malaise
- Papulovesicular rash in trunk and spreads to head/extremities
- Pruritis (itchy skin): Papule, Blister, Ulser
37
Varicella (Chickenpox) Prevent/Control...
- Diagnosed with Tzanck smear
- Antivirals: acyclovir, Foscarnet, Famciclovir, Valacyclovir
- Live, attenuated vaccines
- Varicella
- Zoster (14x more virus)
- varicella-zoster immune globulin
38
Varicella (Chickenpox) complications...
- Varicella pneumonia
- Encephalitis
- Reye’s syndrome
- Postherpetic neuralgia(Shigls)
39
Herpes Zoster (Shingles) signs and symptoms...
-Painful vesicles along course of sensory nerve of the head or trunk
40
Measles Infectious agents
- Morbillivirus: paramyxovirus fam.
- Enveloped (–) RNA
- 2 envelope spikes
- Hemagglutinin
- Cell fusing & hemolytic activity
- single serotype
41
Measles Transmission
- Host: humans
- Person-to-person contact through respiratory droplets
- URT --> Mucosal epithelium
- Epidemics: winter & spring as well as unimmunized/ partially immunized
42
Measles Signs and symptoms
Incubat: 7-18 days (usually 9-11)
- Fever, cough, coryza, conjunctivis
- 1-3 days later: KOPLIK SPOTS lasting 1-2 days
- 1 day later: rash (head trunk/extremities) lasting 3-5 days
43
Measles prevention/control
- Live attenuated vaccine
| - Immune serum globulin
44
Measles complications
- Varicella pneumonia
- Encephalitis
- Reye’s syndrome
45
Roseola infectious agents
- Hum. herpesvirus 6 or 7: Herpesvirus family
| - Enveloped DNA
46
Roseola transmission
-Mainly through saliva
47
Roseola signs and symptoms
- Fever x3 days
| - Faint maculopapular rash spreading from trunk --> extremities
48
Mumps infectious agents
- Mumps virus: Paramyxovirus fam.
- Enveloped (–) RNA
- 2 envelope spikes
- single serotype
49
Mumps transmission
- Host: humans
- Droplets or DC w/ fomites
- URT: blood --> saliv. glands (testes, ovaries, pancreas, meninges)
50
Mumps signs and symptoms
- Incubation: 18-21 days
- Duration: 1 week
- Prodrome: fever, malaise, anorexia
- Tender salivary gland swelling
- Peak: late winter, early spring
51
Mumps control/prevention
Live, attenuated vaccine
52
Mumps complications
- Orchitis in post-pubertal males
| - Meningitis
53
Rubella - “german” measles infectious agent
- Rubella virus: Togavirus family
- Enveloped (+) RNA
- 2 envelope glycoproteins
- single serotype
54
Rubella - “german” measles transmission
Host: humans
- Respiratory droplets
- URT: Blood lymph tissue, skin, organs
- Transplacental spread to fetus = congenital rubella
55
Rubella - “german” measles signs and symptoms
- Incubation: 14-21 days
- Duration: 1-3 days
- Low grade fever, upper respiratory sxs, lymphadenopathy
- W/in 24 hours faint, macular rash to head, neck and trunk as well as petechial lesions over soft palate
56
Rubella - “german” measles control/prevention
-Live, attenuated vaccine
57
Rubella - “german” measles complications
- Arthritis (days – 3 weeks)
- Thrombocytopenic purpura
- Encephalitis
58
Fifth disease – erythema infectiosum infectious agent
- Parovirus B19: Parvovirus family
| - Naked single strand DNA
59
Fifth disease – erythema infectiosum transmission
- Host: humans
- Respiratory or DC w/fomite
- Blood or blood products
- Vertical transmission
- Winter to early summer
60
Fifth disease – erythema infectiosum signs and symptoms
Incubation: 4-12 days
- Duration: 1-2 weeks
- Fever, malaise, headache, myalgias, pruritis
- CHARACTERISTIC 'BLUSH' RASH: confluent, indurated rash to face
- 1-2 days later macular, reticular rash to arms and legs
- Lymphadenopathy, splenomegaly, mild leukopenia, anemia
61
Fifth disease – erythema infectiosum control/prevention
Immunogloblin may be useful (immunodeficiency)
62
Fifth disease – erythema infectiosum complications
- Hepatitis
- Thrombocytopenia
- Nephritis
- Encephalitis
- In pregnancy: profound anemia of fetus
63
What are the gastrointestinal virus infections?
- Rotavirus
- Norwalk virus
- Hepatitis A, B, C, D, E
64
Rotavirus infectious agents
- Rotavirus: Reoviridae family
| - Naked double strand RNA
65
Rotavirus transmission
- Host: humans, animals (calves, mice, piglets, foals) but no interspecies spread
- Fecal-oral route
- Localize in duodenum and proximal jejunum
- cooler months
66
Rotavirus signs and symptoms
- Incubation: 1-3 days
- Duration: vomiting 1-3 days; diarrhea 4-8 days
- Abrupt onset of vomiting, then hours later watery/brown stools
- Low grade fever
67
Rotavirus control/prevention
- live, oral rotavirus vaccine
| - rigorous hygiene measures
68
Rotavirus complications
Dehydration
69
Norwalk virus infectious agents
- Norovirus: Calciviridae family
- Naked (+) RNA
- 4 serotypes
70
Norwalk virus transmission
- Fecal-oral
| - Consumption of contaminated food, water, uncooked shellfish & other foods
71
Norwalk virus signs and symptoms
- Incubation: 10-51 hours
- Abrupt onset vomiting & diarrhea
- Duration: 1-2 days
72
Norwalk virus control/prevention
Hygiene
73
Norwalk virus complications
Dehydration
74
Hepatitis A infectious agent
- Hepatitis A: Picornaviridae family
| - Naked (+) RNA
75
Hepatitis A transmission
- Host: humans, primates
| - Fecal-oral (contaminated food, water)
76
Hepatitis A signs and symptoms
- Incubation: 15-45 days
- Duration: days-weeks
- Fever, anorexia, nausea, RUQ pain, jaundice, dark urine, clay-colored stools, hepatomegaly
77
Hepatitis A control/prevention
- Avoidance of exposure
- Passive immunity- immune serum globulin
- Active immunization – killed HAV vaccine
78
Hepatitis B infectious agent
- Hepadnaviridae agent
- Enveloped, DNA (partially double stranded)
- 4 serotypes
79
Hepatitis B transmission
- Host- humans
| - Vertical, parenterally, sexual contact
80
Hepatitis B signs and symptoms
- Incubation: 30-180 days (avg 10 wks)
- Duration: several months
- Fatigue, anorexia, nausea, RUQ pain/fullness, +/- arthralgias, rash, clay colored stools, dark urine, jaundice
81
Hepatitis B control/prevention
- Interferon and nucleoside and nucleotide analogs
- Hep B immune globulin
- Recombinant vaccine
82
Hepatitis B complications
-Fulminant hepatitis leading to liver necrosis & death; chronic hepatitis associated with cirrhosis, liver failure, HCC
83
Hepatitis D infectious agents
-Enveloped RNA
84
Hepatitis D transmission
-Requires Hep B surface antigen for transmission
85
Hepatitis D signs and symptoms
- Simultaneous D & B infection – looks like HAV or HBV
| - Chronic HBV with superimposed hep D – jaundice relapse & high risk chronic cirrhosis
86
Hepatitis D control/prevention
- Interferon and nucleoside and nucleotide analogs
- Hep B immune globulin
- Recombinant vaccine
87
Hepatitis D complications
-Progressive liver disease, chronic cirrhosi
88
Hepatitis C infectious agents
- Flaviviridae family
- Enveloped (+) RNA
- 11 genotypes, multiple subtypes
89
Hepatitis C transmission
- Hosts: humans
| - Parenterally, may be sexually transmitted
90
Hepatitis C signs and symptoms
- Incubation: 6-12 weeks
- Asymptomatic
- Chronic carrier state in 85%
- 10-18 years to develop chronic hepatitis
91
Hepatitis C control/prevention
- Interferon-α , ribavirin, HCV protease inhibitors
| - No active or passive immunity
92
Hepatitis C complications
-Cirrhosis, increased HCC risk
93
Hepatitis E infectious agent
Naked (+) RNA
94
Hepatitis E transmission
- Host: humans
| - Fecal-oral route
95
Hepatitis E signs and symptoms
- Incubation: 40 days
- Duration: 1-2 weeks
- Often subclinical
- Jaundice, anorexia, hepatomegaly, N/V, fever
96
Hepatitis E control/prevention
No active or passive immunity
97
Hepatitis E complications
When symptomatic can be fatal (esp. in pregnancy)
98
What are the Central Nervous System virus Diseases?
- Enterovirus
- Arboviruses: Meningitis & Encephalitis
- Rabies encephalitis
99
Enterovirus specific groups
- Poliovirus
- Coxsackievirus Group A
- Coxsackievirus Group B
- Echovirus, parechovirus & enterovirus
100
Enterovirus infectious agents
- Picornaviridae family
| - Naked (+) RNA
101
Enterovirus transmission
- Fecal-oral route
- Infects GI & upper respiratory tract
- Spreads to target organs: CNS, heart, vascular endothelium, liver, pancreas, lungs, gonads, skeletal, muscles, synovial tissues, skin
- Increased prevalence – summer, fall
102
Enterovirus signs and symptoms
Incubation varies: 2-10 days
103
Enterovirus control/prevention
Inactivated poliovirus vaccine
104
Arboviruses – arthropod borne infectious agents
- Togavirus: enveloped (+) RNA: Alphaviruses & rubivruses
- Flavivirus: enveloped (+) RNA
- Bunyavirus: enveloped (–) RNA
105
Arboviruses – arthropod borne transmission
- Infected blood-sucking insects (mosquitoes, ticks, sandflies)
- Primarily occur in tropics
106
Arboviruses – arthropod borne signs and symptoms
- Acute febrile illness
- Encephalitis
- Meningitis
107
Arboviruses – arthropod borne control/prevention
-Immunizations for yellow fever, tick-borne, and Japanese B encephalitis
108
Rabies encephalitis infectious agent
- Rhabdoviridae family
| - Enveloped (–) RNA
109
Rabies encephalitis transmission
- Host: All mammals
- Infected secretions (usually bite)
- Site of entry: multiplies in muscle cells then travels to CNS to replicate in brain cells
110
Rabies encephalitis signs and symptoms
-Incubation: 10 days – 1 yr
-Median survival after becoming symptomatic: 4 days, maximum 20 days
... then you are fucked
111
Rabies encephalitis control/prevention
- Pre-exposure: inactivated vaccine
| - Post-exposure: human hyperimmune antirabies globulin plus rabies vaccine
112
Human Immunodeficiency Virus (HIV-1) infectious agent
```
Retrovirus family: Lentivirus genome
-2 copies of enveloped (+) RNA
-3 enzymes essential for viral replication
1. Reverse transcriptase: RNA --> double stranded DNA copy --> integrated into host chromosome
2. Protease
3. Integrase
-Envelope contains 2 viral glycoproteins
gp120 + gp41
```
113
Human Immunodeficiency Virus (HIV-1) transmission
Requires intimate contact with infecting source (bodily fluid, blood)
- Majority from sexual contact
- Perinatal transmission
- Virus has been detected in saliva, tears, urine but not shown to be infectious sources
- Primarily infects and kills helper (CD4) T lymphocytes
114
Human Immunodeficiency Virus (HIV-1) Infectious Cycle
Acute stage: 2-4 weeks after infection
- Fever, lethargy, sore throat, generalized lymphadenopathy, maculopapular rash (trunks, extremities), leukopenia
Latent stage: 7-11 years
- Asymptomatic
- Virus produced and sequestered in lymph nodes
Immunodeficiency stage (AIDS)
- Decline in CD4 cells
115
Human Immunodeficiency Virus (HIV-1) control/prevent
Appropriate screening
- Avoid exposure
- Antiretrovirals
- Pre- and post-exposure prophylaxis
