Immunological preparations in Immunotherapy& Immunoprophylaxis

Immunological preparations: antigen-independent

Immunological preparations: antigen dependent
-Vaccines (antigens)
-Immune sera or Immunoglobulins

Immunization is the method of controlling infections
Immune responses to immunization or immuno-therapy can block the spread of a bacterium, bacterial toxin, or virus to the target organ.
The immunization of population stops the spread of the infectious agent among a community by reducing the number of susceptible to this infection individuals. Such immunization develops herd immunity (national and international levels).
Immunization has succeeded in protecting of popu-lation from the symptoms of pertussis, diphtheria, tetanus; in controlling the spread of measles, mumps, rubella, and in eliminating smallpox in the whole world and poliomyelitis in the Western Hemisphere.

Types of immunization

Active and Passive immunization
Vaccines

Active and Passive immunization
Antibodies
Vaccines
Homologous serum
Heterologous
serum

Artificial passive immunization (API)
API may be used:
To prevent disease after a known exposure (needle stick injury with HBV-contaminated blood);
(2) To protect immunosuppressed patients;
(3) To ameliorate the symptoms of an ongoing disease (chicken pox or measles);
(4) To block the action of bacterial toxins and pre-vent the disease they cause (tetanus, diphtheria).
Sources of antibodies:
Seropositive individuals – donors (homologous);
Animals, hyperimmunised with antigens (heterologous).

Heterologous (animal) serum: Complications
-Hypersensitivity reactions (type I or type III) To prevent these reactions the serum can be given:
(1) by portions with 10-15 minutes intervals
(2) i/m (not i/v) to prevent platelets aggregation and complement activation.

Passive immunization: The preparations

Passive immunization: The preparations (1)

Passive immunization: The preparations (3)

Evolution of Immunoglobulin therapy
Prior to 2014, only convalescent blood products from EHF survivors had been administered to newly infected individuals as a form of treatment.

Evolution of Immunoglobulin therapy
The 2014-2016 Ebola virus outbreak in West Africa was the deadliest in history, prompting the evaluation of various drug candidates, including McAb-based therapeutics for the treatment of Ebola hemorrhagic fever (EHF).

Evolution of Immunoglobulin therapy
the genes encoding for the antibodies were extracted from the hybridomas, genetically engineered to replace mouse components with human components, and transfected into tobacco plants.

Schematic overview of antibody humanization
a The murine McAb
b The chimeric McAb : variable regions are of murine origin, and the rest of the chains are of human origin.
c Humanized McAb : only includes the hypervariable segments of murine origin.
d Human monoclonal.

Schematic overview of antibody humanization
a The murine McAb
b The chimeric McAb : variable regions are of murine origin, and the rest of the chains are of human origin.
c Humanized McAb : only includes the hypervariable segments of murine origin.
d Human monoclonal.

Types of monoclonal antibodies
Naked mAbs are antibodies are the most common type of mAbs used to treat cancer.
Examples:
- Alemtuzumab - chronic lymphocytic leukemia(CLL). They binds
to the CD52 antigen, which is found on lymphocytes (which include the leukemia cells). The antibody cause a first-dose cytokine release syndrome (TNF-α, IL-6 and interferon-γ) and ADCC

Types of monoclonal antibodies
endothelial growth factor
Bevacizumab (Avastin®) is an mAb that targets a protein called Vascular EGF that affects tumor blood vessel growth. It can cause side effects such as high blood pressure, bleeding, poor wound healing, blood clots, and kidney damage.
Cetuximab targets a cell protein EpidermalGFR, which is found on normal skin cells (as well as some types of cancer cells and cause serious rashes.

Monoclonal antibodies in cancer therapy

Conjugated Mabs (Immunotoxins)
Mabs that have been attached to a specific toxic agent.
Ibritumomab tiuxetan (Zevalin®) is an example of a radiolabeled mAb. This is an antibody against the CD20 antigen, which is found on B lymphocytes. The antibody delivers radioactivity directly to cancerous B cells and can be used to treat some types of Non-Hodgkin’s lymphoma.

Immunotoxins
are monoclonal antibodies that have been attached to a specific toxic agent.
The antibody binds specifi-
cally to a target
(tumor) cell and the
attached toxin
affects the target
cell, but not other cells.
This is a promising approach in the treatment of certain types of cancer.

The use of the Artificial Passive Immunization

The use of the Artificial Passive Immunization

The use of the Artificial Passive Immunization

Active immunization
is the induction of an
(1) immune response and (2) immunological memory
in response to a challenge with
an antigen (immunogen).
Immunization occurs after exposure to:
(1) microbes or their antigens in vaccines to prevent the disease (artificial active immunization) or
(2) an infectious agent (natural active immunization) .

The term ‘vaccine’ (Latin ‘vacca’, cow)
This term comes from the first successful immunization against smallpox by cowpox pustule’s material performed by Edward Jenner in 1798 .
Caricature in a British magazine

Smallpox

Vaccination is the artificial active immunization
Louis Pasteur introduced this term recognizing the relevance of Jenner’s research work for his own experiments and for vaccinology as a field of knowledge.

An immunizing agent derived from microorganism is called vaccine
A vaccine consists either of whole organism or microbial extracts and products.
Broadly, vaccines can be subdivided into two groups on the base
(1) whether they infect the
person (live vaccines) or
(2) whether they do not
(inactivated vaccines).

- Conventional vaccines - usually contain inactivated disease-causing organisms or proteins made by the pathogen (antigens), which work by mimicking the infectious agent. They stimulate the body’s immune response, so it is primed to respond more rapidly and effectively if exposed to the infectious agent in the future;

- Advanced vaccines - RNA vaccines use a different : RNA vaccine consists of an mRNA strand that codes for a disease-specific antigen. Once the mRNA strand in the vaccine is inside the body’s cells, the cells use the genetic information to produce the antigen. This antigen is then displayed on the cell surface, where it is recognized by the immune system.

Types of Live Vaccines (LVNs)
LVNs are prepared with organisms limited in the ability to cause disease (avirulent or attenuated).
These organism mimic the natural behavior of the ‘wild’ microbe without causing severe disease.
LVNs may consist of the following types of organisms:
(1) Attenuated (weakened) wild type bacteria or viruses.
(2) Virulent microorganisms from other species that share antigens with human pathogens (Divergent VNs).
(3) Hybrid vaccines that can be used for those pathogens that cannot be properly attenuated.

Live vaccines (1):Attenuated vaccines
They are the wild type bacteria or viruses weakened by modifying conditions under which the organisms grow or by other approaches:
(1) Growing under Nonphysiological Temperature.
(2) Passage in Non-Susceptible Hosts. The mutant organisms do not replicate well in any human cells (host range mutant of rabies virus), or can replicate at a benign site but do not replicate in the target tissues characteristically affected by the disease (polio virus replicates in the GIT but does not reach or infect the brain, as wild type does).
(3) Genetically modified vaccines may be created by genetically engineering mutations that inactivate or delete a virulent gene instead of randomly attenuating the virus through passages.

Live vaccines (2):Attenuated vaccines
Generally attenuation can be achieved by modify-ing conditions under which the organism grows.
The organism can be grown at nonphysiological temperature:
Higher temperature (and anaerobic conditions) - chicken cholera bacillus and anthrax bacil-lus (42,5°С) were cultured by Louis Pasteur ;
(2) Low temperature (320-340C) selects for the growth in embryonated chicken eggs or tissue culture cells of less virulent mutant strains that grow poorly at 370C, and fail to replicate in low respiratory tract (measles, influenza vaccines).

Live viral vaccines (LVVNs):
Immune responses
Immunization with a LVVNs resembles natural infection and elicits both humoral and cell-mediated immune responses.
Most LVVNs designed to protect people against viral diseases, for which the cellular immune response is required for the infection to resolve. These are measles, mumps, polio, rubella, chickenpox, adenovirus, yellow fever.

Effect of vaccination

Effect of vaccination

The Anti-vaccination Movement: A Regression in Modern Medicine

The Anti-vaccination Movement: A Regression in Modern Medicine
There have been recent trends of parents in Western countries refusing to vaccinate their children due to numerous reasons and fears. While opposition to vaccines is as old as the vaccines themselves, there has been a recent surge in the opposition to vaccines in general, specifically against the MMR (measles, mumps, and rubella) vaccine.

The Anti-vaccination Movement: A Regression in Modern Medicine
Almost incredibly, the trigger for what would become a worldwide controversy over vaccine safety was a single scientific research paper published in a medical journal – the Lancet – in February 1998, written by a then-41-year-old academic researcher, Andrew Wakefield, and co-authored by a dozen associates.

The Anti-vaccination Movement: A Regression in Modern Medicine
It reported on the cases of 12 anonymous children with apparent brain disorders who had been admitted to a paediatric bowel unit at the Royal Free hospital in Hampstead, north London, between July 1996 and February 1997. The prime cause of the alarm was findings in the paper claiming that the parents of two thirds of the 12 children blamed MMR for the sudden onset of what was described as a combination of both an inflammatory bowel disease and what Wakefield called “regressive autism”.

Live divergent vaccines: (2) Virulent micro-organisms from other species
that share antigens with human pathogens:
(1) cowpox virus – first vaccine developed against smallpox.
(2) vaccines consisting of bovine or simian rotavirus have shown the initial success in protecting infants against human rotavirus in clinical trials.
(3) Adenovirus vaccines may consist a virulent strains used for oral/GIT administra-tion to induce immunity in respiratory tract.

Newborn baby Rotaviruses vaccine immunization
Rotavirus is a virus that causes diarrhea, mostly in babies and young children. The diarrhea can be severe, and lead to dehydration. Vomiting and fever are also common in babies with rotavirus.
Two rotavirus vaccines are currently licensed for use in infants in the United States:
RotaTeq® (RV5) is given in 3 doses at ages 2 months, 4 months, and 6 months
Rotarix® (RV1) is given in 2 doses at ages 2 months and 4 months

Live vector vaccines:(3)Hybrid vaccines
These VNs can be used for those pathogens that cannot be properly attenuated.
Genes from them can be inserted into safe virus (vaccinia) to form a polyvalent vaccine to many agents in a single, safe, inexpensive, and reliable vector.
On infection, the hybrid virus exp-resses and initiates immune res-ponse to itself and the inserted antigens.
The vaccinia, herpes simplex virus, and adenoviruses have been used in several experimental vaccines.
Nucleoid

Poliomyelitis: Effect of vaccination

Poliomyelitis: Effect of vaccination

Live bacterial vaccines (LBVNs):
Immune responses
LBVNs include attenuated strains Salmonella typhi (typhoid fever), BCG for tuberculosis made from attenuated strain of Mycobacte-rium bovis, and attenuated tularemia vaccine.
A LBVN may be required to elicit protection against infections such as these because both humoral and cellular responses are important to confer protection against intracellular parasites.

Live vaccines: The advantages
(1) The immunity is long live, and mimics the normal immune responses.
(2) When vaccine is administrated orally, SIgA is secreted in the gut and oropharynx to protect the mucous (oral polio vaccine, OPV).
This prevents the establishing of carrier state and facilitates the near eradication of the wild type virus from the community.
(3) Live vaccines are administrated in low doses. Basically one single administration is enough for protection because organisms multiply in a body.

Live vaccines: The disadvantages
(1) they may cause disease
in immunosuppressed
individuals and should be
replaced by the other type
of vaccine (OPV can be
replaced by IPV);
(2) the vaccine may revert to
virulent form.

Inactivated vaccines (IVNs)
IVNs provide safe antigen for immunization and are used to confer protection against most bacteria and viruses that may be too virulent to be attenuated or may be oncogenic.
IVNs can be produced by chemical modification with formalin, by heating of the organism or its products (bacterial toxins), by purification of the bacterial or viral components.
IVNs can be of tree major types:
(1) whole killed (for bacteria) or inactivated (for viruses);
(2) capsule (for bacteria) or subunit (for viruses);
(3) toxoid (for bacterial toxins).

Whole killed & Inactivated viral vaccines

Capsule vaccines for bacteria and subunit vacines for viruses
They can be developed after identification of the microbial components, that elicit a protec-tive immune response–protective antigens.
Immunogenic component may be isolated from bacterium or viruses:
(1) by biochemical means (chemical vaccines) or
(2) by genetic engineering (recombinant vaccines) involving the expression of cloned viral genes in bacteria or eukariotic cell.

Capsule & Subunit vaccines (VNs)

Mucosal Synthetic Conjugated Vaccine (Peptides)
Nanoemulsion droplet (200 nm) with antigen
Fusion with dendritic
cells deliveres antigen
Nasal
epithelium

Influenza vacccines

Toxoids (TDs)
TDs are exotoxins converted to non-toxigenic but still immunogenic form. Immunization with the TD provokes the formation of protective antibodies which neutralize the toxin and facilitate the toxin removal by phagocytosis.
TDs are poor immunogenic and should be adminis-trated with adjuvants (alum - Al(OH)3 or Al(PO4) or can be covalently attached to a protein antigen.
TDs need booster shots to conform protection.
Vaccines that contain toxoids are for tetanus, diphtheria, cholera, botulism.
Composite vaccine DPT contains 2 toxoids absor-bed on alum – diphtheria and tetanus – and whole killed pertussis cells.

Toxoids: Induction of antitoxins

Adjuvants
The target site of vaccine adjuvants. Most of the recently developed specific adjuvants, such as pattern recognition receptor (PRR) ligands act on signal 0 (antigen recognition and antigen-presenting cells [APCs] activation), and indirectly on signal 2 (co-stimulation). In addition, PRR ligands can act on signal 1 (efficient presentation of the co-administered antigen).

Recombinant/DNA approaches in vaccines

DNA vaccines
DNA vaccines consist of naked DNA code for a gene for vaccinal protective antigen. This construct is produced
by cloning gene, code for
protective antigen, into
a bacterial plasmid.
The use of DNA vaccines makes possible developing vaccines against infectious agents such as HIV, herpes virus, malaria, and others, which require not only humoral but also cellular immune responses for protection.

Plasmid DNA for gene vaccination
has two major units:
(1) A transcription unit comprising promoter, an antigen cDNA, and poly-adenylation (A) addition sequence, which together direct protein synthesis.
(2) A plasmid backbone deli-vers adjuvant and mitoge-nic activity via immuno-stimulatory sequences (ISS ). ISS are located within the ampicillin antibiotic resistance gene (ampR). ISS are the noncoding region of the plasmid.

Immune responses elicited by DNA vaccines
The DNA plasmid is injected into the muscle cell or skin of the vaccine recipient.
The plasmid can be uptaken by both muscle cell and antigen-presenting cell (APC).
The gene for the antigen (Ag) will be expressed in muscle cell and this antigen will be produced by the recipient muscle cells in large amounts.
(1) When uptaken by APC, the Ag can be presented on the APC together with class MHC-II to activate T helper cells to mediate humoral immunity.
(2) When the Ag is produced and presented as
endogenous Ag together with class MHC-I on the surface of the muscle cell, it can elicit TH1
cell-mediated immune response.

Transfection of host cells with plasmid DNA
Plasmid (O) is taken up by host cells (actively or passively).
Antigen (Ag) produced by transfected myocytes is taken up by bone mar-row (BM)–derived antigen presenting cells (APCs).
BM-APCs can be trans-fected directly also.
Ag-bearing APC then can process and present anti-genic peptides com-plexed with MHC-molecu-les to the immune system after migration to lymphoid tissue.

DNA Vaccines
At present, several different DNA- based vaccines are on clinical trails against malaria, HIV, influenza, hepatitis B, and others. There is a special device for delivery – the gene gun.

Recommended Immunization Schedule for