Vaccination (6) Flashcards
What are some viral mechanisms to avoid the immune response?
latency in protected sites
growth in immune cells
antigenic drift and shift
suppression of class I MHC molecules to prevent CTL mediated killing of infected cells
production of proteins that block signaling of cytoikkine and antiviral pathways for interferon
What are the 3 main approaches to making a vaccine?
using a whole virus or bacterium
parts that trigger the immune system
just the genetic material
T/F: All vaccines should satisfy requirements of efficacy, purity, potency, and safety
TRUE
What is the “historical vaccines”?
Jennerian (use of closely related less virulent viruses)
What are “work horse vaccines”?
live attenuated (slowed) vaccines
inactivated vaccines
What are “new generation vaccines”?
recombinant and genetically engineered vaccines
nucleic acid vaccines (DNA & mRNA)
Most vaccines on the market are either inactivated or live ______, but _____ are now in use
attenuated
recombinant vaccines
What’s an example of a live attenuated vaccine?
canine distemper
What are live attenuated vaccines?
the modified live virus replicates in the host
produces longer-lasting immunity similar to that of natural infection
generally better immunogens
usually most successful
What are the advantages of attenuated vaccines?
single dose may be effective
can be given by a natural route, stimulating local and systemic immunity
produces long-lived immunity
inexpensive
What are the disadvantages of attenuated vaccines?
possible reversion to virulence
possible spread to in contact animals and fetus
possible contaminating viruses or mycoplasmas
may not be attenuated for all species
What are the advantages of inactivated vaccines?
stability
no danger of spread
no problem with viral interference
fatal viruses can be controlled
What are the disadvantages of inactivated vaccines?
multiple doses often required to protect
no local immunity or interferon produced
high concentration of antigen causes them to be expensive
immunity often short-lived
any non-inactivated virus can cause disease
What are adjuvants?
agents used to enhance the immunologic response to inactivated vaccines
What do adjuvants cause?
a slower release and degradation of antigens and stimulate phagocytosis
_____ is one widely used adjuvant but other products such as iscoms are used
Aluminum hydroxide
Who researched the human genome project?
Craig Venter
What are gene deleted vaccines?
virulent genes are removed or modified - so not virulent
attenuated
Which vaccine type is not virulent?
gene deleted vaccines
The first field test of a genetically altered virus vaccine took place in _____ in the US
1985
Who genetically altered the first virus for vaccines?
Saul Kit
What are marker vaccines?
an important advance for disease control
pioneered with pseudorabies (herpesvirus)
______ gene-deleted vaccines led the way in the 1980s in the USA
Pseudorabies
How is the marker vaccine created?
removing genes not essential for virus replication
attenuating the vaccine by removing the thymidine kinase
so, two genes are deleted
animal still produced protective antibodies but animal doesn’t go sick and virus doesn’t become latent
________ is a disease people are working on application of gene-deleted marker vaccines
Infectious bovine rhinotracheitis
Early vaccines were based on ____ virus
vaccinia (the virus used to control smallpox)
What are recombinant pox vaccines?
insert gene
able to be transcribed and mRNA translated, yielding sufficient immunogenic protein to confer immunity
Since only the genes coding for the major immunogenic proteins are selected for expression in the vector, such vaccines can also be adapted to be _______ compatible
DIVA
_____ (company) produced vectored vaccines based on canarypox virus rather than ______.
Merial
fowlpox
T/F: A vaccine attenuated for one species may not be attenuated to another
TRUE
Why can you use canarypox or fowlpox to make a gene-based recombinant vaccine?
it does not replicate in mammals, so there is no danger of CDV viral particles
What is an insect baulcovirus?
commonly used to produce protein; gene-coding for the antigenic protein has been inserted into the virus
- protein is produced in vitro and purified before injection into the target species
- adjavents often used to potentiate the immune response
What vaccine method has the greatest efficacy?
live attenuated virus
Which vaccine has the least efficacy but is the safest?
nucleic acid vaccines (DNA and mRNA vaccines)
Which vaccine was the first licensed DNA vaccine in 2005?
a vaccine that protects horses from West Nile Virus
How do mRNA vaccines work?
virus uses messenger RNA which is synthesized from a template which then instructs them to make proteins
mRNA inside an oily shell made of lipid nanoparticles to not be degraded by enzymes
What are characteristics of an ideal vaccine?
provides broad-spectrum protection
long-lasting and effective
inexpensive to manufacture
simple to administer
avoiding reversion to virulence
long shelf life and heat stable
allows discrimination between infected and vaccinated animals
used in dam to protect newborn
can overcome colostral immunity
if adjuvanted, does not induce cancer
Why do some vaccines fail to protect?
improper use
genetic differences between animals
antigenic differences
blocking by maternal antibodies
administration following infection
_______ antibodies can interfere with vaccination but also be insufficient to block infection
Maternal
What are the AAFP core vaccines?
panleukopenia, herpes, calci, rabies
intranasal vs. parenteral
age of vaccination
What are AAFP noncore vaccines?
FeLV, FIP, chlamydia, bordetella
What does acyclovir and famciclovir block?
herpesvirus DNA polymerase
can be used for therapy against feline herpes virus 1 ocular infections
What is paxlovid?
inhibits a key enzyme that the COVID virus requires in order to make functional virus particles
What is Remdesivir and GS441524?
nucleotide analogue antiviral drug; used for FIP
_____ vaccines have allowed for an epidemiological approach to controlling viral diseases
gene-deleted vaccines
Viruses with large ___ _____, such as poxviruses, can be manipulated - inserting only the gene encoding a surface glycoprotein allows for expression of the most antigenic part to the host’s immune system
DNA genome
