Bacterial Vaccines Flashcards
Most common type of vac
Inactivated
Bacterins- where the whole culture or bacterial cells are enriched with pathogenic determinants or pars of a bacterial cell
Contain sufficient antigen to stimulate antibody production- generally requires 2 doses in order to generate sufficient response for protection
Formaldehyde inactivates/denatures pro (may modify surface antigens)
Preserved with phenol
Mixed with adjuvant
Antigens preserved in inactivated vac
Fimbrae Capsules Outer membrane pros Cell wall lipopolysaccharides Iron binding proteins and heat shock proteins Prototoxins and toxins/toxoids Other secreted antigens
Use of inactivated vaccines
Im 2 or more injections IgM and IgG Poor mucosal and cellular immunity Poor duration of immunity Passive immunity for offspring
Toxoids
Stimulate the formation of toxin neutralizing antibodies
Usually contain adjuvants
Good for clostridial bc they rely on toxins for infection
Adjuvants
Inactivated vac contain to enhance the immune response
Induce inflammation at the site of vaccination, may cause local irritation at inj site
AlOH, Aluminum phosphate, mineral oil/liquid paraffin
Component vaccines
one or more protective antigens - toxoid secreted antigen and/or structural proteins
Use is becoming more common
Require a moderate amount of antigen, so cost decreases and decreased side effects
Administer with adjuvant
Live
Not many at the present, many have been withdrawn. Control of attenuation is difficult, and may revery to virulence in vivo. Give via natural route
Live microorganisms that have lost the ability to cause disease/non -pathogenic forms of infecting organism. Allows them to retain many/all surface antigens. Replicate in host, but dont cause disease
Stimulate CMI and antibody both locally and systemically- colonize and replicate on the surface of appropriate mucosa
Immunity long lasting, but generally less than that of a natural infection
Canine bordatella, Cattle bacillus anthracis (no capsule, but still has toxin), Salmonella enteritidis for poultry (oral), and fungal for ring worm in cattle
Passive immunity
Provided by the dam
Requires first administration and boost, given before parturition
Hyperimmune antisera
Commercially available preparations of antisera produced by immunizing horses/cattle
Sera contain the appropriate antibodies or antitoxins- provide passive protection when unimmunised and exposed
May produce hypersensitivity in recipient of sera
Subunit vac
Critical epitope(s) destroyed by inactivation
Poorly immunogenic
May still be toxic if insufficiently treated
Target genes for attenuating bac
Genes coding for virulence factors
Regulatory genes
Metabolic pathway genes
Stress-response genes
Rational attenuation of bacterial pathogens
Clone target gene
Inactivated gene (deleted portion of gene)
Introduce mutated gene into bacteria
Homologous recombination replaces wild type with mutates
Check genotype and phenotype of mutant bacteria
Check attenuation and immunogenicity
Pre chorismate (aro) pathway
Required for synthesis of aromatic compounds in bacteria, fungi, and plants
Precursors- phosphoenol pyruvate + erythrose-4-PO4
Chorismate, branch point for the biosynthesis of aromatic amino acids, PABA (not produced by vert, must obtain from diet but bac cant use exogenous folate), DHBA, vitamins, and modified nucleosides (tRNA)
Mutation in one or more aro gene is highly attenuation
Potentially virulent in immunocompromised individuals
Salmonella aro mutants
Mutation in one or more aro genes are highly attenuated, and under go limited replication in vivo
S. typhi aro mutants are safe and immunogenic in humans, as S.typhimurium aro mutants are in many animals
Oral vac of calves with live recombinant salmonella vac
S. typhinimurium aroA and aroD, give orally at 7 days, 3 weeks later they were challenged and all vac were fully protected
