Classical Vaccines

Vaccines can eradicate pathogens and save lives

Vaccines have been made for 36 of >400 human pathogens

Immunological Bioinformatics, The MIT press.

+HPV & Rotavirus

DodoPathogenic Viruses

Data derived from /www.cbs.dtu.dk/databases/Dodo.

1st column: log10 of the number of deaths caused by the pathogen per year

2nd column: DNA Advisory Committee (RAC) classificationDNA Advisory Committee guidelines [RAC, 2002] which includes those biological agents known to infect humans, as well as selected animal agents that may pose theoretical risks if inoculated into humans. RAC divides pathogens intofour classes.Risk group 1 (RG1). Agents that are not associated with disease in healthy adult humans

Risk group 2 (RG2). Agents that are associated with human disease which is rarely serious and for which preventive or therapeutic interventions are often available

Risk group 3 (RG3). Agents that are associated with serious or lethal human disease for which preventive or therapeutic interventions may be available (high individual risk but low community risk)

Risk group 4 (RG4). Agents that are likely to cause serious or lethal human disease for which preventive or therapeutic interventions are not usually available (high individual risk and high community risk)

3rd column: CDC/NIAID bioterror classificationclassification of the pathogens according to the Centers for Disease Control and Prevention (CDC) bioterror categories A–C, where category A pathogens are considered the worst bioterror threats

4th column: Vaccines available A letter indicating the type of vaccine if one is available (A: acellular/adsorbet; C: conjugate; I: inactivated; L: live; P: polysaccharide; R: recombinant; S staphage lysate; T: toxoid). Lower case indicates that the vaccine is released as an investigational new drug (IND)).

5th column: G: Complete genome is sequenced

Vaccines work by preparing the immune system so it can respond faster and stronger when challenged

The addaptive Immune system

Figures by Eric A.J. Reits

Vaccination

•Vaccination

•Administration of a substance to a person with the purpose of preventing a disease

•Traditionally composed of a killed or weakened micro organism

•Vaccination works by creating a type of immune response that enables the memory cells to later respond to a similar organism before it can cause disease

Early History of Vaccination

•Pioneered India and China in the 17th century

•The tradition of vaccination may have originated in India in AD 1000

•Powdered scabs from people infected with smallpox was used to protect against the disease

•Smallpox was responsible for 8 to 20% of all deaths in several European countries in the 18th century

•In 1721 Lady Mary Wortley Montagu brought the knowledge of these techniques from Constantinople (now Istanbul) to England

•Two to three percent of the smallpox vaccinees, however, died from the vaccination itself

•Benjamin Jesty and, later, Edward Jenner could show that vaccination with the less dangerous cowpox could protect against infection with smallpox

•The word vaccination, which is derived from vacca, the Latin word for cow.

Early History of Vaccination II

•In 1879 Louis Pasteur showed that chicken cholera weakened by growing it in the laboratory could protect against infection with more virulent strains

•1881 he showed in a public experiment at Pouilly-Le-Fort that his anthrax vaccine was efficient in protecting sheep, a goat, and cows.

•In 1885 Pasteur developed a vaccine against rabies based on a live attenuated virus

•A year later Edmund Salmon and Theobald Smith developed a (heat) killed cholera vaccine.

•Over the next 20 years killed typhoid and plague vaccines were developed

•In 1927 the bacille Calmette-Guérin (BCG vaccine) against tuberculosis vere developed

Vaccination since WW II

•Cell cultures

•Ability to grow cells from higher organisms such as vertebrates in the laboratory

•Easier to develop new vaccines

•The number of pathogens for which vaccines can be made have almost doubled.

•Many vaccines were grown in chicken embryo cells (from eggs), and even today many vaccines such as the influenza vaccine, are still produced in eggs

•Alternatives are being investigated

Vaccination Today

•Vaccines have been made for only 36 of the more than 400 known pathogens that are harmful to man.

•Immunization saves the lives of 3 million children each year, but that 2 million more lives could be saved if existing vaccines were applied on a full-scale worldwide

Categories of Vaccines

•Live vaccines

•Are able to replicate in the host

•Attenuated (weakened) so they do not cause disease

•Subunit vaccines

•Part of organism

•Genetic Vaccines

•Part of genes from organism

Vaccines have been made for 36 of >400 human pathogens

Immunological Bioinformatics, The MIT press.

+HPV & Rotavirus

Vaccines under IND in the US•Venezuelan equine encephalomyelitisvirus

•Live

•Western equine encephalomyelitis virus

•Inactivated

•Estern equine encephalomyelitis virus

•Inactivated

•Coxiella burnetii

•Inactivated, Available in South Amerika; Lisenced vaccine in Australia

•Francisella tularensis

•Live

•Hantaan virus

•Live

•Rift Valley fever virus

•Inactivated, live

•Junin Virus

•Live, Available in South America

Live Vaccines

•Characteristics

•Able to replicate in the host

•Attenuated (weakened) so they do not cause disease

•Advantages

•Induce a broad immune response (cellular and humoral)

•Low doses of vaccine are normally sufficient

•Long-lasting protection are often induced

•Disadvantages

•May cause adverse reactions

•May be transmitted from person to person

Subunit Vaccines

•Relatively easy to produce (not live)

•Induce little CTL

•Viral and bacterial proteins are not produced within cells

•Classically produced by inactivating a whole virus or bacterium

•Heat

•Chemicals

•The vaccine may be purified

•Selecting one or a few proteins which confer protection

•Bordetella pertussis (whooping cough)

•Create a better-tolerated vaccine that is free from whole microorganism cells

Subunit Vaccines: Polysaccharides

•Polysaccharides

•Many bacteria have polysaccharides in their outer membrane

•Polysaccharide based vaccines

•Neisseria meningitidis

•Streptococcus pneumoniae

•Generate a T cell-independent response

•Inefficient in children younger than 2 years old

•Overcome by conjugating the polysaccharides to peptides

•Used in vaccines against Streptococcus pneumoniae and Haemophilus influenzae.

Subunit Vaccines: Toxoids

•Toxins

•Responsible for the pathogenesis of many bacteria

•Toxoids

•Inactivated toxins

•Toxoid based vaccines

•Bordetella pertussis

•Clostridium tetani

•Corynebacterium diphtheriae

•Inactivation

•Traditionally done by chemical means

•Altering the DNA sequences important to toxicity

Subunit Vaccines: Recombinant

•The hepatitis B virus (HBV) vaccine

•Originally based on the surface antigen purified from the blood of chronically infected individuals.

•Due to safety concerns, the HBV vaccine became the first to be produced using recombinant DNA technology (1986)

•Produced in bakers’ yeast (Saccharomyces cerevisiae)

•Virus-like particles (VLPs)

•Viral proteins that self-assemble to particles with the same size as the native virus.

•VLP is the basis of a new vaccine against human papilloma virus (HPV)

For more information se: http://www.nci.nih.gov/ncicancerbulletin/NCI_Cancer_Bulletin_041205/page5

Genetic Vaccines

•Introduce DNA or RNA into the host

•Injected (Naked)

•Coated on gold particles

•Advantages

•Easy to produce

•Induce cellular response

•Disadvantages

•Low response in 1st generation

•Genes can also be carried by genetically modifies viruses or bacteria

Epitope based vaccines

•Advantages (Ishioka et al. [1999]): Epitope based vaccines

•Can be more potent

•Can be controlled better

•Can induce subdominant epitopes (e.g. against tumor antigens where there is tolerance against dominant epitopes)

•Can be designed to break tolerance

•Can target multiple conserved epitopes in rapidly mutating pathogens like HIV and Hepatitis C virus (HCV)

•Can overcome safety concerns associated with entire organisms or proteins

•Epitope-based vaccines have been shown to confer protection in animal models ([Snyder et al., 2004], Rodriguez et al. [1998] and Sette and Sidney [1999])

Passive Immunization

•Antibodies harvested from infected patients or animals are then used to protect against disease [Marshall et al., 2003]

•Used in special cases against many pathogens:

•Cytomegalovirus

•Hepatitis A and B viruses

•Measles

•Varicella

•Rubella

•Respiratory syncytial virus

•Rabies

•Clostridium tetani

•Varicella-zoster virus

•Vaccinia

•Clostridium botulinum

•Corynebacterium diphtheriae

Therapeutic vaccines

• Vaccines to treat the patients that already have a disease

• Targets

• Tumors

• AIDS

• Allergies

• Autoimmune diseases

• Hepatitis B

• Tuberculosis

• Malaria

• Helicobacter pylori

• Concept

• suppress/boost existing immunity or induce immune responses.

Cancer vaccines

• Strategies

• Induce immune response (break tolerence) against overexpressed self antigens

• Target mutated proteins

• Therapeutic cancer vaccines can induce antitumor immune responses in humans with cancer

• Antigenic variation is a major problem that therapeutic vaccines against cancer face

• Tools from genomics and bioinformatics may circumvent these problems

Se also: http://cis.nci.nih.gov/fact/7_2.htm

Allergy vaccines

• Increasing occurrence of allergies in industrialized countries

• The traditional approach is to vaccinate with small doses of purified allergen

• Second-generation vaccines are under development based on recombinant technology

• Genetically engineered Bet v 1 vaccine can reduce pollen-specific IgE memory response significantly

• Example of switching a “wrong” immune response to a less harmful one.

Figure by Thomas Blicher.

Therapeutic Vaccines against Persistent Infections• For example for preventing HIV-related disease progression

• Most of the first candidate HIV-1 vaccines were based entirely or partially on envelope proteins to boost neutralizing antibodies

• Envelope proteins are the most variable parts of the HIV genome Vaccines composed of monomeric gp120 molecules induce antibodies that do not bind to trimeric gp120 on the surface of virions

• A number of recent vaccines are also designed to induce strong cell-mediated responses.

• Escapes from CTL responses are associated with disease progression and high viral loads

• Some CTL epitopes escape recognition quickly because they are not functionally constrained, others might need several compensatory mutations because they are in functionally or structurally constrained regions of HIV-1

Vaccines Against Autoimmune Diseases• Multiple sclerosis

• T cells specific for mylein basic protein (MBP) can cause inflammation of the central nervous system.

• The vaccine uses copolymer 1 (cop 1), a protein that highly resembles MBP. Cop 1 competes with MBP in binding to MHC class II molecules, but it is not effective in inducing a T cell response

• On the contrary, cop 1 can induce a suppressor T cell response specific for MBP, and this response helps diminish the symptoms of multiple sclerosis

• A vaccine based on the same mechanisms is developed for myasthenia gravis

More information: http://www.ninds.nih.gov/disorders/multiple_sclerosis/detail_multiple_sclerosis.htm,

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12667659&query_hl=4

Vaccines Market

• The vaccine market has increased fivefold from 1990 to 2000

• Annual sales of 6 billion euros

• Less than 2% of the total pharma market

• Major producers (85% of the market)

• GlaxoSmithKline (GSK), Merck, Aventis Pasteur, Wyeth, Chiron

• Main products (>50% of the market)

• Hepatitis B, flu, MMR (measles, mumps, and rubella) and DTP (diphtheria, tetanus, pertussis)

• 40% are produced in the United States and the rest is evenly split between Europe and the rest of the world [Gréco, 2002]

• It currently costs between 200 and 500 million US dollars to bring a new vaccine from the concept stage to market [André, 2002]

More information:Gréco, 2002André, 2002

Trends

• From

• Whole live and killed organisms

• Problems

• Adverse effects

• Production

• To

• Subunit vaccines

• Genetic vaccines

• Challenges

• Enhance immunogenecity