Exam 1 Flashcards
(132 cards)
1
Q
What detects viral nucleic acids?
A
Polymerase chain reaction
2
Q
What are the tests used in diagnosis of viral diseases?
A
- Virus isolated in tissue culture cells (detect infectious virus)
- ELISA/Immunocytochemistry (detects viral antigens/proteins)
- PCR/Sequencing (detects viral nucleic acids)
- Serology (detects antibody to virus)
3
Q
What is the most common cause of vaccination failure in puppies?
A
Interfering levels of maternal antibodies block the development if an immune response
4
Q
T/F: The modified live vaccines are NOT susceptible to inactivation
A
False
–> They are very susceptible and proper handling and storage is critical
5
Q
When are modified live vaccines preferred?
A
Modified live vaccines produce a higher level immune response and are the choice for situations where multiple injections are not feasible like during disease outbreak, for shelter and feral animals
6
Q
What is primary viremia?
A
When there is virus present in the blood
7
Q
T/F: Vaccines do NOT prevent infection
A
True
–> They reduce replication of the virus and prevent/mitigate disease
8
Q
What does a positive laboratory result generally mean?
A
- -> It confirms the presence of either a specific virus or antibody to a virus
- -> A positive virus result also means the animal was infected at the time of sampling.
9
Q
What is direct contact transmission?
A
Transmission between cohabitating animals
–> Respiratory route including aerosol droplets
10
Q
What are the different types of entries for a virus?
A
- Membrane fusion or Hemifusion state
- Endocytosis
- Pore mediated penetration
- Phagocytosis
11
Q
What remains the most definitive diagnostic test?
A
Microscopic Examination
12
Q
If viremia (virus in blood) occurs what happens in the body?
A
Serum IgG can bind the virus and block entry of the virus into the cells
13
Q
The ______ from which the specimen is collected will be influenced by the clinical signs and knowledge of the pathogenesis of the suspected virus
A
site
14
Q
T/F: The purpose of vaccinating animals (administrating a killed or weakened virus or its genes, subunit components, DNA/RNA) is to prevent infection with the target virus
A
False
15
Q
What is a recombinant vector vaccine?
A
Engineered by incorporation if genes for a pathogen’s antigenic proteins into a harmless carrier virus.
- -> It can induce a robust immune response in the host (Ab and cell mediated)
- -> It cannot revert to virulence/cause disease
16
Q
What is a virion?
A
Vehicle for transmission
17
Q
What could a positive antibody result mean?
A
That the animal was previously infected, vaccinated, or the animal still has maternally-derived antibodies
18
Q
Most routine tests are _____ specific
A
virus
–> They are designed to detect a specific virus and will give a negative test result if the target virus is not present in the sample, even if other viruses are present in the sample … most times
19
Q
Vaccination with high titer vaccines could result in …
A
Positive PCR tests for 7-10 days with no wild type virus or disease (parvovirus)
–> Can also result in a positive ELISA
20
Q
If you are unsure which samples to test and which test to use, who should you call?
A
VMDL or other diagnostic labs and discuss
21
Q
Determination of antibody status is relevant for the assessment of what conditions?
A
If the animal has unknown vaccination history, are overdue for vaccines, those undergoing chemotherapy, those receiving immunosuppressive drugs, as well as those with a history of vaccine adverse reactions
22
Q
Describe a non-enveloped virus
A
- -> Fomite transmission (long survival in environment)
- -> Retains infectivity on drying and can survive on surfaces
- -> Released via lysis of infected cell
23
Q
Examples of viruses that transferred between hosts to gain new host ranges
A
Influenza –> Birds –> Pigs/Equine/Human
Canine Parvovirus –> Cats –> Dogs
Canine Influenza –> Equine/Avian –> Dogs
24
Q
What are important factors for respiratory transmission of a virus?
A
Titer of the virus in the infected animal, distance between animals and air movement
25
What is contained in vaccines that can enhance vaccine response by modulating innate and adaptive immunity?
Adjuvants
26
T/F: Detection of a virus is NOT dependent on appropriate collection of samples
False
| -> It is appropriate (the site, animal, and time)
27
Unfixed samples for virus detection assays such as ..
PCR (viral nucleic acids)
| ELISA (viral antigen or isolation of virus)
28
T/F: Mutation of viral genes occur to greater or lesser extent with all viruses
True
| --> Many of these mutations do not make obvious or dramatic changes in disease or host range
29
Describe a virus envelope
- Sensitive to heat, drying, detergents, acid
- Must stay moist to be transmitted to new host
- Transmitted in droplets, secretions, feces
- Does not need to kill cells in order to spread (budding)
- Do not survive long in the environment like non-enveloped viruses
30
What is the AVMA definition of core vaccines?
Vaccines that protect from diseases that are endemic to a region, those with public health significance, required by law, caused by viruses that are virulent/highly infectious and/or those posing a severe risk of disease
31
Why are new viruses emerging?
Mutation of viral genes occur to greater or lesser extent with all viruses and these can result in infection/disease in new host species
32
Where there is an acute virus infection when should a sample be taken?
ASAP after the individual develops clinical signs, or sample multiple animals
33
Different transmissions by virus shedding animals
- Respiratory route = aerosol
- Oral route = saliva
- Fecal route = enteric viruses
- Milk, Skin, Urogenital tract
34
T/F: Virus replication and shedding occurs before and during fever (clinical signs)
True
35
Avian influenza virus is carried by
Migratory birds
| - Ducks, geese, and others
36
What does a negative laboratory result generally mean?
The specific virus or antibody tested for was not detected and it is often assumed that the animal was not infected with the virus
37
What type of antibody is produced on first exposure to an antigen?
IgM
38
What type of antibody is induced by contact of antigen with a mucosal surface?
IgA
39
What is the best test to confirm for FIPV?
Immunocytochemistry
40
The high titers in modified live vaccines may produce ...
A higher level immune response (Ab and cell mediated immunity) and may be more likely to overcome low levels of maternal Ab
41
What are some exceptions to why a laboratory result can come back negative?
1. Wrong timing of sample (animal was infected but the target virus is no longer present)
2. Wrong choice of sample (target virus does not replicate and is not shed in a tissue that the sample is from)
3. Wrong animal (in herd sample is from an animal that is not infected with the target virus but another animal in the herd is)
42
Sample the _____ or the ______ that is most likely to contain the virus (hunt where quarry is most likely to be found)
tissue or the location
43
What is vertical transmission?
A virus that is transmitted from parent to offspring
- Germplasm (genetic material of an organism that may be transmitted from one generation to the next)
- Through the egg
- Across the placenta
- - Milk
44
What is antigenic drift?
Mutation of viral genes which is directed by requirement to retain function and escape detection by existing antibodies
***May be responsible for the large number of serologically distinct strains of many viruses***
45
How do viruses acquire new host range?
Contact between the virus and host, infection of an initial individual leading to amplification and an outbreak, and the generation within the original or new host of viral variants (mutations in original virus) that have the ability to spread efficiently between individuals in populations of the new host
46
What 2 things are important in conferring protection from a viral pathogen?
Antibodies and cell mediated immunity
47
What are the objectives of vaccination?
Disease prevention or mitigations
- -> Protect individual animals from disease, decrease shedding and transmission to other animals
- -> Protection of the unvaccinated population (herd protection, public health in the case of rabies)
48
IgM response can be detected as early as ..
4 days after vaccination and 6 days after inoculation
49
What is not a good sample for virus detection?
Blood
50
Feline infectious peritonitis virus is an example of ....
a) virus induced immune mediated inflammatory disease
b) latent infection in trigeminal ganglia
c) induction of immunologic tolerance
d) integration of viral genome into DNA host
a
51
T/F: Rabies vaccines (killed or subunit) offer excellent and long-lasting immunity (protection)
True
52
What are modified live vaccines derived from?
Naturally occurring pathogen and are produced by generation of non-virulent virus by attenuation in cell culture
53
T/F: Animals infected with virus may or may not have disease when shedding virus
True
| --> Some virus infected animals replicate virus and shed without any clinical signs
54
Increased severity of disease can occur by mutations that result in infection of ...
New cell type and different effects upon infected cells
55
Why is it important for us to try to diagnosis disease?
To manage the disease in the animal and/or herd
56
What is important in recovery from established virus infections?
Cell mediated immunity
57
T/F: The PCR test (diagnostic test for viral nucleic acids) detects specific virus and will give a negative test result of the target virus of not present in the sample even if other viruses are present in the sample
True
58
The antibody that is produced upon repeated exposure to Ab and that offers systemic protection
IgG
59
What is herd immunity?
When the vast majority of animals are vaccinated (70-90% depending on how contagious) it is more difficult for an outbreak of disease to occur/spread
60
What 3 groups are animal viruses divided into?
DNA
RNA
RT (reverse transcribing)
61
What is the vaccine type that is most likely to induce sarcomas in cats and may be associated with adjuvants in rabies?
Inactivated vaccines
62
T/F: Infection with both strains (H3N2, H3N8) has been reported in nearly all states
True
63
T/F: The percentage of dogs infected with canine influenza that die is very large
False
| --> Very small percentage of dogs die from canine influenza
64
T/F: Modified live vaccines have decreased potential for allergic reactions
True
65
T/F: Vaccination always results in protective immunity
False -- Not necessarily
| --> Level of protection and length of time protection lasts varies with individual vaccines and animals
66
What is the definition of non-core vaccines?
These are vaccines that are based on risk-assessment, they are not recommended for every animal
67
Clinical signs may be helpful when deciding when to take a sample, but exceptions are... and what should be done to help?
Virus replication may not coincide with the observed clinical signs and some animals shed viruses without observable clinical signs
- -> Multiple samples in a herd
- -> Multiple samples from the same animal
- -> Samples for virus and Ab can also be helpful
68
What are fixed samples for?
Microscopic examination and immunocytochemistry assays for viral antigen in lesions
69
What test detects viral proteins of Ab to a virus?
ELISA
70
What canine strain emerged in Asia and likely rose through the direct transfer of an avian influenza virus?
H3N2
71
What is the reason for DVM to study viral pathogenesis?
Knowledge of how these viruses infect animals and cause disease is required for diagnosis, management, and prevention of viral diseases
72
What type of vaccine is safe for pregnant and immune-suppressed animals?
Inactivated Vaccines
73
Inactivated vaccines are _____ and require _____
stable and require adjuvants
74
CIV was first identified as a factor in canine respiratory disease. What is this virus a genetic variant of?
H3N8 equine influenza virus that gained the ability to infect dogs
74
CIV was first identified as a factor in canine respiratory disease. What is this virus a genetic variant of?
H3N8 equine influenza virus that gained the ability to infect dogs
75
Where does lentivirus persist?
Lymphocytes or macrophages
76
Which is not an example of vertical transmission?
a) retrovirus is integrated into the germplasm
b) a horse is bitten by an arthropod infected with the west Nile virus
c) a pestivirus crosses the placenta and infects the fetus
d) a lentivirus is secreted into milk ingested by a neonate
b
77
What is the basis for vaccine protection?
In a vaccinated animal the responses occur faster and reach higher levels
78
What are the most common local reactions to vaccines?
Pain, pruritis, alopecia, lameness - transient common
79
In veterinary medicine, vaccines are used to ...
prevent and manage viral disease they DO NOT PREVENT INFECTION
80
Why are antibodies necessary?
They prevent initial entry of a virus and decreases the initial load of virus in the blood
81
Describe virus structure
1. Nucleic acid core (DNA or RNA)
2. Capsid no envelope (DNA or RNA)
3. Envelope (DNA or RNA)
--> Some viruses have an envelope and others do not
82
What are inactivated vaccines?
They are not infectious (virus replication does not occur in the host) there is no reversion to virulence, and there is no shedding of virus after immunization
- -> They generally induce less robust immune response than modified live vaccines
- -> Require a higher antigen mass, adjuvant, multiple doses, and more frequent boosters
83
What is endocytosis?
The host cell takes in a viral particle through the process of receptor-mediated endocytosis (canine parvovirus)
84
What is the certification of freedom from specific infections?
Diseases in which there is persistent infection (sometimes life-long) such as bovine leukemia, bovine diarrhea, equine infectious anemia, equine herpes
--> So a negative test is required for these certain diseases - a negative test certificate - for sale, movement, exhibitions, or competitions
85
What are mutations of viral genes used in?
Epidemiological studies to track spread of virus in host population
86
What antibodies are commonly produced following viral infection?
IgG, IgA and IgM
87
Define elimination
Locally without total eradication of the causative virus
88
What is the frequency of vaccination determined by?
Characteristics of each viral pathogen in its host species
89
Modified live vaccines usually contain _____ titers and _____ passage strain of the target virus
High
| Low
90
What are viral inclusion bodies?
Nuclear or cytoplasmic aggregates of viral substances, usually capsid proteins. They typically represent sites of viral multiplication in a cell (enveloped/non-enveloped and DNA/RNA may for inclusions)
91
What is a monovalent vaccine?
Designed to immunize against a single antigen or single microorganism
92
Where do most canine influenza outbreaks commonly occur?
In facilities where dogs are housed together and there is the frequent introduction of new dogs
- shelters, kennels, boarding
93
What test detects Ab to a virus?
Serology
94
Viral mutations can lead to increased _____ of disease in a host
severity
95
Where do retroviruses persist?
Lymphocytes
96
T/F: A virus may or may not cause disease
True
97
What site to sample for viral respiratory infection
Nasal, throat swabs, lung tissue from dead animals
98
Viruses can undergo mutations which can result in all of the following EXCEPT
a) change in host range
b) altered disease-causing properties
c) multiple serological strains of virus
d) make epidemiological studies track spread of virus not possible
d
99
What are some reasons why vaccines may not be as effective?
- Incorrect storage
- Past expiration date
- Incorrectly administered
- Genetic differences
- Immunosuppression
- Concomitant disease
100
T/F: Persistently infected animals are the least important source of infection of other animals
False
101
If the virus has already infected cells (intracellular) or has established a persistent or latent infection, what is more, important than a systemic antibody for protecting this animal?
Cell-mediated immunity
102
What is disease surveillance?
Detection of foreign animal disease, detection of new and emerging viruses that cause disease of animals
103
What is the duration of immunity to canine distemper virus following vaccination?
3 years
104
T/F: Canine parvovirus is a result of a host range change in feline panleukemia virus
True
105
How fast can immunity against a virus or vaccine begin to develop?
4-6 days IgM
106
What is a major histocompatibility complex?
Proteins found on the surface of cells that help the immune system recognize foreign substances including viruses
107
Primary IgM response can be detected as early as..
4 days after vaccination and 6 days after inoculation with a virulent strain of CDV
108
T/F: Vaccination results in positive Ab tests for many common viral diseases
True
| --> Ab levels vary enough between animals that interpretation can be inconclusive from a single sample
109
Most commercially available vaccines protect against all the ...
relevant strains in circulations
110
What is membrane fusion/hemifusion state?
The cell membrane is punctured and made to further contact with the unfolding viral envelope of the receptor-mediated endocytosis (herpes, influenza, retroviruses)
111
Where does the herpes virus persist?
Neurons of sensory ganglia
112
Method of control of virus infections
Prohibition or restriction on the movement or importation of animals and animal products from areas where exotic disease occurs.
113
What day can viral shedding occur by?
7 post-infection and it can persist for 60-90 days
114
T/F: Viruses cannot persist in a wide variety of cells of the host
False -- they can
115
Serum IgG levels do not correlate well with the protection in ...
Persistent or latent infections
116
Define eradication
Ideal goal but few viruses have been eradicated by immunization (smallpox)
117
What type of vaccine is rabies?
Inactivated or recombinant vectored vaccine
**NO modified live rabies vaccine**
118
What is a multivalent/polyvalent vaccine?
Designed to immunize against two or more strains of the same microorganism, or against two or more microorganisms
119
T/F: It is easy to differentiate between Ab response to a vaccine and response to WT CDV in a single sample
False -- it is difficult
| --> Shows overlap in values following vaccine and WT virus, need to know vaccine history
120
Define disease prevention
Efficacious vaccines protect individual animals from disease caused by the virus that is the target of the vaccine if administered before exposure
* Goal of most animal vaccines
121
Cats can be infected with the _____ strain and show signs of upper respiratory disease
H3N2
122
What is antigenic shift?
Exploits the segmented nature of influenza and Bluetongue virus genome and therefore, not used in a wide variety of viruses
** Most likely responsible for the most severe influenza epidemics
123
What may be possible for many serologically distinct strains of many viruses?
Mutation of viral genes for surface proteins (Antigenic Drift)
124
What are serum IgM positive titer resuls for canine distemper virus
1:40 positive
125
What are puppy vaccines?
Grouped together (core vaccines) include multivalent or combination vaccine administration as modified live virus
126
T/F: Mutations can result in infection and disease in new host species
True
127
What type of vaccine may revert to virulence?
Modified live vaccine -- rare
128
What test detects viral proteins?
Immunohistochemistry
129
Increased transmission and severity of disease can occur by mutations that result in ..
increased viral replication (disease causing property of virulence of many viruses is related to increased ability to replicate in cells of hosts)
130
What site to smaple for routine enteric cases
Feces or small intestine
131
What is secondary viremia?
The spleen is a site of massive viral replication which can lead to secondary viremia
--> At the time of viremia peaks and begins to decline systemic clinical signs are likely to occur
