14. Immunodiagnosis, Immunotherapy & Vaccination

王 家 鑫，MD

College of Veterinary Medicine

14.1 Immunodiagnosis

• ELISA for animal disease diagnosis

Enzyme-linked immunosorbent assay(ELISA)

— detection of antigen

— detection of antibody• Immunological colloidal gold signature

(Immunochromatography),

(Colloidal gold immunoassay， GIA) • Immunofluorescence diagnosis

Detection of CSFV antibody in swine serum, plasma or whole blood

Immunochromatography

Detection of microbal antigens by immunofluorescence staining

Rabies virus in salivary gland herpes simplex virus

14.2 Immunotherapy

• IFN-α/IFN-βare used for virus infection.

• IFN-γis better than IFN-α/IFN-β.

• GM-CSF and IL-2 for the treatment of bovine mastitis.

• Anti-TNF-αtherapy

Cytokine therapy

Immunomodulating agents

• Biological response modifiers

• Immunosuppressors

• Traditional Chinese veterinary medicine

• Antibody therapy

14.3 Vaccination

1. Active Immunization

vaccines

2. Passive Immunization

Antibody

Passive Immunization

• Vaccines

♥ The generation of a controlled adaptive immune response that will protect an individual from pathogenic infection/

disease.

♥ Induction of immunological memory.

Types of vaccine approaches to common pathogens

• Attenuated organism: live, but non-pathogenic Give good CD8 T cell responses because they lead

to intracellular protein synthesis. Some risk of reversion or pathogenesis in immunodeficient animals.

• Killed whole organism: heat, chemical fixation. Does not elicit as good CD8 response. Inactivated

whole bacteria can cause unwanted inflammation.• Subunit vaccine: specific protein of microorganism Safe, can be effective. Problems of poor CD8 respo

nses and low natural adjuvancy.

• Conjugate vaccine: Specific portion of microorganism (Often carbohydrate) linked to carrier protein.

This is the basis of recent vaccines for infants for Haemophilus influenzae (bacterial menigitis) and pneumococci.

• DNA vaccines: introduce plasmid DNA directly into host cells.

Relatively cheap, specific, and targets CD8 cells. Technical problem of getting DNA into host cells (Gene gun). Some safety concerns.

• Recombinant vectored vaccines: putting new genes in attenuated organism (such as vaccinia)

Still experimental, but works well in animals. Safety concerns.

• Modern adjuvants (TLR agonists), cytokines

CpG DNA (TLR9 agonist). Cytokines that boost growth or numbers of dendritic cells (GM-CSF), T cell responses (IL-2). Target best APCs.

14.3.1 Live, Attenuated Vaccines

14.3.2 Inactivated or “Killed” Vaccines

• Pathogens are inactivated by heat or chemical means.

• Killed vaccines often require repeated boosters to maintain the immune status of host.

• Killed vaccines induce a predominantly humoral immune response; they are less effective than attenuated vaccines in inducing cell-mediated immunity and in eliciting IgA response.

14.3.3 Subunit Vaccines

• Inactivated exotoxins(Toxoids)

• Capsular polysaccharides

• Recombinant protein antigens

Conjugate vaccines provide a peptide

that stimulates CD4 T cells to antigens

that lack good determinants, such

as bacterial capsular polysaccharides.

Stimulates a good IgG antibody response to t

he carbohydrate

14.3.4 Conjugate vaccines

Immune stimulatory complexes(ISCOMs) delivery system

ISCOMs are lipid carriers that act as adjuvants but have minimal toxicity. They seem to load peptides and proteins into the cell cytoplasm, allowing MHCclass I-restricted T-cell response to peptides todevelop.

Lipid + Peptides

Epitopes on VP1 protein of foot-and-mouth disease virus (FMDV)

14.3.5 DNA vaccine

• The DNA vaccine is a plasmid that contains one or more genes of the pathogen that is being immunized against behind a strong eukaryotic promoter. Transcription and translation occur from the vaccine plasmids that find their way into the nucleus of the muscle cells, to make the pathogen-derived protein.

Gene gun

14.3.6 Recombinant Vector Vaccines

Mammalian cells

独特型疫苗

Swine flu goes global

The genetics of the virus are so novel that humans are unlikely to have much immunity to it, scientists say. The current seasonal flu vaccine, which targets a different H1N1 strain, also isn't likely to offer any protection. Discussions are under way as to whether a new vaccine for the swine flu strain should be produced. The WHO has recommended that vaccine makers continue to manufacture the seasonal flu strain but begin thinking about how to manufacture large doses of a vaccine that incorporates a weakened version of the current swine flu strain. For now, the virus is treatable with the influenza drugs oseltamivir (Tamiflu) and zanamivir (Relenza).

Thank You