Ethel's Literacy Blog: Two:Immunisation: Immune System and Vaccines.

Immunisation
Immunisation against disease is a natural process as the human immune system adapts biologically to protect hosts against infections but has limitations in its defence against deadly viruses and infections.

Immunisation vaccines are developed by medical science in strictly regulated methods through the manufacturing process of creating vaccines against disease.
Human Immune System (Biological)

Knowing how the immune system or biological aspect works in the human body is how medical science created vaccines.The immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. Protection is built up through the immune system in two ways, it creates natural/native and adaptive immunisation against disease by breaking into two arms:

Viruses and other foreign substances can evolve rapidly, and adapt to avoid the immune system and allows them to successfully infect their hosts.
Innate immunity is the first line of defense against infections. Innate immunity is specifically against microbes, while adaptive immunity is against any "foreign" substance (including cancer cells, auto antigens, etc.).
Innate immunity is the oldest mechanism of defence.

The human immune system adapts over time to recognize viruses and specific foreign substances more efficiently. This adaptation process is referred to as "adaptive immunity" or "acquired immunity" and creates immunological memory.
Adaptive immunity (T and B lymphocytes) is superimposed on innate immunity to improve host defence. In a sense, adaptive immunity is an "add-on" to innate immunity.
1:INNATE
Innate immunity (natural or native immunity)
Instant
Immediate
Initial response
Induces adaptive immunity
Integrates with adaptive immunity

2:ADAPTIVE
Adaptive immune system
Acquired
Await days = no immediate response
Accurate = specific
Auto regulation
Autoimmunity

Immunological memory, created from a innate response to a specific virus or foreign substance, provides an enhanced response to secondary encounters with that same, infection.

This process of acquired immunity this is where vaccinations are useful, the innate response can take 2 days and up to 2 weeks to develop. After the body gains immunity towards a certain virus or foreign substance, when infection by that virus occurs again, the immune response is called the secondary response.
Immunisation Vaccines (How does it work)

HOW IMMUNIZATIONS WORK

Immunizations teach your body how to defend itself when germs such as viruses or bacteria invade it.

They expose you to a very small, very safe amount of a virus or bacteria that has been weakened or killed.
Your immune system then learns to recognize and attack the infection if you are exposed to it later in life.
As a result, you will either not become ill or have a milder infection. This is a natural way to deal with infectious diseases.

Four different types of vaccines are currently available:

LIVE VIRUS VACCINES use the weakened (or attenuated) form of the virus. The measles, mumps, and rubella (MMR) vaccine and the varicella (chickenpox) vaccine are examples of this type.

KILLED (Inactivated) VACCINES are made from a protein or other small pieces taken from a virus or bacteria. Influenza shots are an example of this type of vaccine.

TOXOID VACCINES contain a toxin or chemical made by the bacteria or virus. They make you immune to the harmful effects of the infection, instead of to the infection itself. Examples are the diphtheria and tetanus vaccines.

BIOSYNTHETIC VACCINES contain human-made substances are very similar to pieces of the virus or bacteria. The Hib (Haemophilus influenzae type B) conjugate vaccine is one example.

The Manufacturing Process

Manufacturing an anti-virus vaccine today is a complicated process created with in the sterile laboratory environment.
There are SEVEN Steps taken in producing immunisation vaccines

1: Manufacturing begins the Seed Small amounts of a specific virus (or seed).

The virus must be free of impurities, including other similar viruses and even variations of the same type of virus. The seed must be kept under "ideal" conditions, usually frozen, that prevent the virus from becoming either stronger or weaker than desired. Stored in small glass or plastic containers, amounts as small as only 5 or 10 cubic centimeters, but containing thousands if not millions of viruses, will eventually lead to several hundred liters of vaccine. Freezers are maintained at specified temperatures; charts and/or dials outside of the freezer keep a continuous record of the temperature. Sensors will set off audible alarm signals and/or computer alarms if the freezer temperature goes out of range.

2: Growing the virus ( After defrosting and warming).

Warming the seed virus under carefully specified conditions (i.e., at room temperature or in a water bath), the small amount of virus cells is placed into a "cell factory," a small machine that, with the addition of an appropriate medium, allows the virus cells to multiply. Each type of virus grows best in a medium specific to it, established in pre-manufacturing laboratory procedures, but all contain proteins from mammals in one form or another, such as purified protein from cow blood. The medium also contains other proteins and organic compounds that encourage the reproduction of the virus cells. As far as the virus is concerned, the medium in a cell factory is a host for reproduction. Mixed with the appropriate medium, at appropriate temperature, and with a predetermined amount of time, viruses will multiply

3: Other Factors

In addition to temperature, other factors must be monitored, including the pH of the mixture. pH is a measure of acidity or basicity, measured on a scale from 0 to 14, and the viruses must be kept at a defined pH within the cell factory. Plain water, which is neither acidic or basic (neutral) has a pH of 7. Although the container in which the cells are growing is not very large (perhaps the size of a 4-8 quart pot), there are an impressive number of valves, tubes, and sensors connected to it. Sensors monitor pH and temperature, and there are various connections for adding media or chemicals such as oxygen to maintain the pH, places to withdraw samples for microscopic analysis, and sterile arrangements for adding the components of the cell factory and withdrawing the intermediate product when it is ready.

4: Begin Virus Separation from the Medium

The virus from the cell factory is then separated from the medium, and placed in a second medium for additional growth. Early methods of 40 or 50 years ago used a bottle to hold the mixture, and the resulting growth was a single layer of viruses floating on the medium. It was soon discovered that if the bottle was turned while the viruses were growing, even more virus could be produced because a layer of virus grew on all inside surfaces of the bottle. An important discovery in the 1940s was that cell growth is greatly stimulated by the addition of enzymes to a medium, the most commonly used of which is trypsin. An enzyme is a protein that also functions as a catalyst in the feeding and growth of cells.In current practice, bottles are not used at all. The growing virus is kept in a container larger than but similar to the cell factory, and mixed with "beads," near microscopic particles to which the viruses can attach themselves. The use of the beads provides the virus with a much greater area to attach themselves to, and consequently, a much greater growth of virus. As in the cell factory, temperature and pH are strictly controlled. Time spent in growing virus varies according to the type of virus being produced, and is, in each case, a closely guarded secret of the manufacturer.

5: Separation

When there is a sufficient number of viruses, they are separated from the beads in one or more ways. The broth might be forced through a filter with openings large enough to allow the viruses to pass through, but small enough to prevent the beads from passing. The mixture might be centrifuged several times to separate the virus from the beads in a container from which they can then be drawn off. Still another alternative might be to flood the bead mixture with another medium which washes the virus off the beads.

and selecting the strain

The eventual vaccine will be either made of attenuated (weakened) virus, or a killed virus. The choice of one or the other depends on a number of factors including the efficacy of the resulting vaccine, and its secondary effects. Ru vaccine, which is developed almost every year in response to new variants of the causative virus, is always an attenuated vaccine. The virulence of a virus can dictate the choice; rabies vaccine, for example, is always a killed vaccine.

6: If the vaccine is attenuated (Weakened)

The virus is usually attenuated ( to make less complex or to weaken) before it goes through the production process. Carefully selected strains are cultured (grown) repeatedly in various media. There are strains of viruses that actually become stronger as they grow. These strains are clearly unusable for an attenuated vaccine. Other strains become too weak as they are cultured repeatedly, and these too are unacceptable for vaccine use. Only some viruses are "just right," reaching a level of attenuation that makes them acceptable for vaccine use, and not changing in strength. Recent molecular technology has made possible the attenuation of live virus by molecular manipulation, but this method is still rare.

7: Virus is then Separated from the Medium

The virus is then separated from the medium in which it has been grown. Vaccines which are of several types (as most are) are combined before packaging. The actual amount of vaccine given to a patient will be relatively small compared with the medium in which it is given. Decisions about whether to use water, alcohol, or some other solution for an injectable vaccine, for example, are made after repeated tests for safety, sterility, and stability.

Quality Control

To protect both the purity of the vaccine and the safety of the workers who make and package the vaccine, conditions of laboratory cleanliness are observed throughout the procedure. All transfers of virus and media are conducted under sterile conditions, and all instruments used are sterilized in an autoclave (a machine that kills organisms by heat, and which may be as small as a jewel box or as large as an elevator) before and after use. Workers performing the procedures wear protective clothing which includes disposable tyvek gowns, gloves, booties, hair nets, and face masks. The manufacturing rooms themselves are specially air conditioned so that there is a minimal number of particles in the air.

The Approval Process

In order for immunisation vaccines to be distributed a drug manufacturer must meet strict licensing requirements established by law.All prescription drugs must undergo THREE phases of testing, although data from the second phase can sometimes be used to meet third phase requirements.
Phase 1 testing must prove that a medicine is safe. If a medicine passes will go onto phase II.
Phase II testing, it must next be tested for efficacy—it must do what it is supposed to do; vaccines cannot be distributed unless it does exactly what it advertises.
Phase III testing is designed to quantify the effectiveness of the vaccine.Immunisation vaccines are expected to have effectiveness close to 100%.
The entire manufacturing process is reviewed carefully by the examination of records involving procedures as well as government representatives visiting the manufacturing site itself.
Each step in the manufacturing process must be documented, and the manufacturer must demonstrate a "state of control" for the manufacturing process.
This means that records must be kept for every step in the process, and there must be written instructions for each step of the process.