lecture7 Flashcards
What are the types of vaccines??
Live attenuated
-virulent in a diff species—> like cox pow, caused disease in cows but did not cause in human but still replicated
-infectious but not disease
-loss of virulence mutants
-adapted to the cold
-genitcally manipulated
Inactivated
What is the goal of vaccination?
What is sterilizing immunity?
Establish protective immune response without causing disease
-effective provide disease protection
Rendered someone functionally resistant to infection—- some vaccines do this and some do not
What is the duration of immunity, thermostability, breath of immunity, reversion to virulence, cost between live and inactivated
Live:
Long term
Low temps
Good
Occasional
Low
Inactivated:
Shorter
Higher
Poor
None
Low
What is the IPV vaccine ?
What did it give?
What does it protect against?
Inactivated polio vaccine
Trivalent—> given via injection
Serological immunity
Protects against disease, not infection
What is the OPV vaccine?
What immunity did it give?
Protects against?
Oral polio vaccine—> live attenuated
Trivalent
Mucosal immunity
Protects against infection
What are problems with vaccine use??
What is an example of this?
What is difficult to control with vaccines?
-Live vaccine can revert to virulent form
-Vaccines in immunocompromised person can be threatening
-side effects
-expensive
Live polio vaccine no longer used in US bc strains can cause vaccine reversion
-organisms with many serotypes are diff to control w vaccine
-don’t know what responses are required for immunity
What are subunit vaccines?
Ex?
What are recombinant viruse vaccines, HPV & J&J Covid ?
Immune response to single protein confers immunity
-hep B surface antigen
HPV—virus like particles , viral protein coat but not genomes
Covid vaccine—chimeric
-includes gene for Cov2 spike, delivers DNA but does not replicated
What are nucleic acid vector vaccines?
DNA, RNA Vaccine
Covid- stabilized spike protein
What are viral vectors ?
Adv and dis?
Harmless virus which is altered to contain part of COVID-19 genetic code
Adv: less expensive, more stable than RNA
dis: immunity to vaccine virus, may limit repeated used
What are mRNA vaccines ?
Advantages?
Dis??
Improvements ?
Contains synthetic version of part of COVID19 genetic code
Adv:
translated in cells so can stimulate production of antibodies and T cell responses
-easy to change sequence
Dis: expensive
Needs cold
Improvements:
Lipid nanoparticles for RNA devliery
Generation of modified RNA that do not trigger innate immune response —>pseudouridine mod
What is herd immunity?
What vaccines are less effective or at causing herdimmunity?
Lack of susceptibility / possession of immunity in most people in a population greatly reduces the probability that individuals will be infected
This is why even if small set of the population is
Those that do not cause sterilizing immunity —> COVID
what are 8 factors that contribute to success or failure of vaccination campaigns?
1) human as sole reservoir — small pox
2) rate of asymptotic infection
3) modes of transmission
4) number of strains:
-few for polio so only have to add a few serotypes
-rate of evolution for flue is really high
5) virus replication properties
6) immune reponse to viral antigens that do not achieve goals of vaccination—ex: RSV
7: economics of vaccine development
8: immune compliance
why can people be successfully vaccinated after contact with rabies?
–rabies is slow replicating,
–people that get vaccine initiated acquired immune responses can develop rapidly enough to prevent disease even when immunization is after infection
why would smallpox be easier to eliminate vaccination than influenza?
–smallpox replicates only in humans and has a low inapparnt/ asymptomatic rate
–influenze has a lot serotypes
what is a confounding factor?
how do they complicate the dengue infection?
what is ADE mechanism?
other factors than appear to be incommon between groups and appear to cause something, but actually don’t
-dengue people who get infected again get the disease worse the second time
-appears to be due to ADE
-antibody binding to virions allows target cell binding via antibodies constant region
&
- the virus initiations replication cycles more efficiently in presence of the antibodies
why isn’t ART good enough?
viral suppression does not cure
can lead to CMV/ EBV tumors
neurological effects— HAND happens in about half of patients (HIV associated neurocognitive disorders)
what are 2 proposed HIV cure strategies:
transplanting
and shock and kill, what are they?
HIV-resistant cell transplantation or gene editing:
-Based on patients cured using CCR5-Δ32 mutant bone marrow transplants.
-Promising but not broadly applicable due to the risks and complexity of bone marrow transplants.
“Shock and kill” strategy:
-Use of latency-reversing agents to reactivate hidden virus so immune system can destroy infected cells.
-Experimental, still being tested in trials.
what is the difference between herpes latency, untreated HIV latency and latent reservoirs of HIV?
-Herpesvirus latency: No active replication; virus remains as unintegrated DNA in long-lived cells with minimal/no gene expression.
-Untreated HIV clinical latency: Misleading term—it’s a chronic phase with ongoing active replication, but at low levels due to immune suppression.
HIV latent reservoirs: In patients on ART, HIV persists as integrated, transcriptionally silent proviruses in a small number of cells, capable of reactivation.
what is the likelihood of developing AIDS after stopping HAART?
Very high: Virus replication almost always resumes after stopping HAART.
HIV is not eradicated by HAART, so stopping treatment typically leads to progression toward AIDS
what are 2 components to HIV persistence?
Chronic replication (in untreated individuals): Active replication with continuous cell death.
Latent infection (in ART-treated individuals): Silent, integrated proviruses remain in some cells. These can reactivate and reignite infection, requiring lifelong treatment.
what is PrEP ( pre exposure prophylaxis?
-preventative using low does antivirals in high risk HIV negative individuals
-effective when consistent
-Lenacapvir show great promise
