vaccines and vaccinations Flashcards
vaccine
a preparation of an immunogenic material used to induce immunity against pathogenic organisms (product you use)
vaccination
intentional administration of a harmless or less harmful form of a pathogen to induce specific immune response that protects the individual against later exposure to the pathogen
the way we take advantage of the body’s normal immune response to PROTECT animals fr. disease
vaccinated or not?
- consider costs/risks and benefits (economic decision)
What is main objective of vaccination?
- passive transfer of immunity => vaccinated breeder, progeny come w/ immunity
- active immunity => own immune system protects us
- immunity against disease & infection
- sterile immunity: elimination of pathogen before it replicates
- vaccination in face of infection/disease
non-infectious application of vaccination
- vaccines to induce self tolerance => expose to different levels of antigen and person gets used to it
- anti-cancer vaccines (Marek’s in poultry)
- vaccines against drug addiction
- contraceptive vaccines
the ideal vaccine
- safe: vaccine itself must not cause illness or death
- protective: must protect against illness resulting fr. exposure to live pathogen
- gives sustained protection: must last several years
- induces neutralizing antibody: some pathogens like poliovirus infect cells that cannot be replaced
- neutralizing antibody essential to prevent infection of such cells
- induces protective T cells: some pathogens, particularly intracellular, are more effectively dealt w/ by cell mediated responses
- practical considerations: low cost per dose, biological stability, ease of administration, few side-effects
immunity
2 types
- innate: non-specific, already present at birth
- acquired: resistance that individual develops after exposure (like vaccine)
- initial cell mediated response to antigen
- macrophages, neutrophils, NK cells
- T & B cells: acquired (generate memory)
- cell mediated response (T cells)
- humoral or antibody response from B cells
Primary and secondary
primary immunogenic stimulus
- latent period -> exponential phase (IGM) -> primary response where first antibody shows up (at steady state)
- IgM turns into IgG as it declines
secondary immunogenic stimulus
- faster time in response
- IgM -> IgG (secondary response is memory response that causes high IgG and longer in time)
what do we look on vaccines?
- safety
- do limited harm to recipient
- stimulate protective immune response against pathogens
- maximize return on investment (food animal)
what is in a vaccine vial
- micro-organisms: live, attenutated, inactivated or parts of microorganisms)
- certain parts of bacteria
- adjuvant, immunological agent that increases the antigenic response (mostly in inactivated vaccines)
- something put into vaccine to stimulate the antigenic response
- preservatives, formaldehyde, gentamycin, dyes etc.
vaccines available in poultry medicine
live virus transformed into modifided live virus, inactivated virus, or recombinant product
modified live virus: isolate from wildtype, let it grow, do it many times => when put in chicken, can have secondary effects
- will cause full immune response => innate, adapted, great immune response and memory
inactivated virus: get virus and mix it w/ formalin which kills virus and fixes product (keep structure of protein in good shape) which allows virus to generate good immune response
- problem: doesn’t replicate so not constantly stimulating immune response
- need adjuvants to stimulate more than one
recombinant: inserting gene of interest into vector that will generate protein that induces in immunity that’s protected
- generates antibodies in host that’s protective against disease
live virus -> purified subunits
isoalte portions of virus => can use that as vaccine
strategies explored as vaccines (CoV)
inactivated: sinovac => approved abroad
mRNA: moderna and pfitzer/BioNTech => emergency use approved
virus vectored: J&J => emergency use approved
virus-like particles: Novavax => waiting for ER use approval
- largest amount of vaccine candidates in clinical and pre-clinical stages
- aim for 95% protection
types of vaccines
side note: primary infection can get infected by bacteria
ex: clear -> green snot
live or modified live vaccines (MLV)
- live attenuated product
- replicate in the animal and shed to others
- stimulate cell mediated and humoral immunity (complete immunity)
- long lasting immunity
-vaccinated population => if not, have rolling infection
killed vaccines
- inactivated
- don’t replicate in animals
- stimulates humoral immunity (Ab’s), requires priming (w/ live vx)
- short lived systemic immunity (1-2 yrs)
- stimulate primarily B-cells Ab but no SMI
- safer, no reversion to virulence
- good for producing antibodies
-good first response = better 2nd response (at least 2 doses)- may require revaccination throughout animal’s life = jey to immunologic memory
- adjuvants: stimulate greater response
- maybe cause adverse reactions
- injection site granulomas
- pathogen isn’t causing flu, the agulents are => can cause severe secondary effect
recombinant vaccines
- a live vector carries gene (fr. pathogen) encoding a protein of immunogenic interest
- long lived immunity thanks to live vector b/c vector constantly replicating => generates lots of antibodies
- generates immunity to the gene of interest (GOI) and vector
- make sure there is no previous immunity to the vector (neutralizes the vaccine)
- very safe
- require liquid nitrogen storage
safety of the vaccines
MLV
- can induce disease (reversion to virulence) => b/c didn’t vaccinate whole population, virus jumps to other chickens and is getting adopted again
- may cause abortion in mammals
- requires refrigeration to keep it alive
killed vaccine
- safer, no reversion to virulence
- adjuvant often irritating (granuloma formation)
- difficult to apply (parenteral)
- expensive: the encapsulation, not mRNA
recombinants
- safe, no reversion to virulence
- applied in ovo, IM or SC (poultry)
- expensive
routes of administration
- parenteral: intramuscular (IM), subcutaneous (SC), intradermal (ID)
- mucosal: oral, nasal, rectal, ocular, and vaginal (spray, drinking water, gel)
- epidermal and transcutaneous delivery
- in-ovo immunization (chickens)
- fetal immunization (mammals)
