Proteins are the important constituents of our body. They are required for various metabolic and vital functions. However, their deficiency causes several diseases. In recent years various protein- based products have been commercialised and many are under trials. Some of the recombinant products and described herewith.

1. Blood Products :

Blood consists of various cells and plasma proteins. Traditionally volunteers have been donating blood to patients, e.g. blood donation by volunteers to patients of a-thalasemia.

Since decades, blood banks have been established at many centres at commercial level. Besides, blood plasma is also available commercially, for example antivenum given against snake-bite.

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In recent years, many blood products have been produced through recombinant DNA technology, for example blood clotting factor VIII for treatment of haemophilia A, factor IX for treatment of haemophilia B, Christmas disease, erythropoietin in anaemia of chronic renal failure, etc.

2. Synthetic and Recombinant Vaccines :

Vaccines are the proteins produced by B-lymphocytes which combat and inactivate the antigens including viruses. Traditionally attenuated (inactivated) viral preparations have been in use as vaccine. In recent years, synthetic and recombinant vaccines have been commercialised.

India’s first genetically engineered vaccine (Hepatitis B vaccine) against Hepatitis B virus was developed by Shantha Biotechnics P Ltd (Hyderabad) in 1997. These vaccines are cheaper and safer as compared to inactivated vaccines. The other vaccines are:

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(i) The vaccine for Foot and Mouth Disease Virus (in animals)

(ii) MMR vaccine for Mums, Measles and Rubella (MMR), etc.

(iii) The GnRH (gonadotropin releasing hormone) vaccine is a semi-synthetic vaccine for treatment of carcinoma of the prostrate

(iv) The hCG (human chorionic gonadotropin) vaccine used in birth control

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(v) The HSD (heterospecific dimer)- hCG vaccine is used as fertility control vaccine.

3. Therapeutic Antibodies and Enzymes

Our blood contains mixture of antibodies called polyclonal antibodies. Since centuries, polyclonal antibodies have been used in therapy of many diseases.

In 1984, Kohler and Milstein along with Neil Jerne were awarded with Nobel Prize for the discovery of production of monoclonal anibodies (MoAb).

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Now, monoclonal antibodies are being produced through ‘hybridoma technology’. The MoAb is being used therapeutically in various conditions and diseases as given below:

(i) OKT3 is used to prevent acute kidney transplantation

(ii) OKT3 is also used to purge donor bone marrow prior to its use in marrow transplantation so as to reduce host rejection

(iii) ReoPro for prevention of blood clots

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(iv) Anti-CEA for treatment of colorectal carcinoma

(v) CAMPATH-1H (chimeric) is given for treatment of certain lymphomas

More than 100 MoAb-based preparations are under clinical trials and in near future these will be available in market.

In addition, there are several enzymes produced through recombinant DNA technology. These are used in therapy of many diseases. Examples are given below:

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i. DNase for treatment of cystic fibrosis

ii. Tyrosine hydroxylase for treatment of Parkinson’s disease

iii. Tissue plasminogen activator (t-PA) for acute myocardial infarction

iv. Asparaginase for treatment of some types of cancers

v. Gluco-cerebrosidase for Gaucher’s disease i.e. glucocerebrosidase deficiency.

4. Enzymes Used in Diagnostic Assays :

The components to be determined (analytes) are used as substrate in an enzyme-catalysed reaction with a detectable signal i.e. a positive or negative charge in absorption. This assay system depends on substrate specificity of enzymes.

5. Therapeutic Growth-factors and Hormones :

Human growth factors and hormones are required by human body for various functions related to growth. For example, traditionally insulin was prepared from the pancreas of cows and pigs.

Thereafter, chemical approach was made to synthesise insulin. The first genetically engineered human insulin (Humulin) was produced in 1980 by E. Lilly & Co. (U.S.A). by using genetically engineered E. coli. Human insulin gene was transferred into E. coli cells which produced insulin.

Humulin acts within 15 minutes as compared to pig insulin which acts after 3 hours. The other therapeutic growth hormones produced commercially are as below:

i. Somatotropin used against Turner’s syndrome in girls

ii. Platelet-derived growth factors for diabetic and skin ulcers

6. Regulatory Factors :

Proteins which are not hormones but associated with regulation of cell growth have also been produced commercially, for example interferons, interleukins, colony stimulating factors, tumour necrosis factors, etc.

Interferon’s are the proteins which are produced after viral infection to interfere the multiplication of viral particles. There are three types of interferon in humans:

(i) Alpha interferon (INF-a) or leukocyte interferon (produced by leukocyte of blood).

(ii) Beta interferon (INF-p) or fibroblast interferon (produced by fibroblast of connective tissues).

(iii) Gamma interferon (INF-y) or immune interferons (produced by blood lymphocytes).

In 1980, INF-a and INF-(3 were successfully produced from genetically engineered E. coli cells, and INF-y later on.

These interferon’s have wide therapeutic application. INF-a is applied for the cure of Hepatitis C, INF-(3 for multiple sclerosis, and INF-y for chronic granuloma.