Vaccines:
Vaccines are made using several different processes. They may contain live viruses that have been attenuated, inactivated, or killed organisms or viruses, inactivated toxins where toxins generated by the bacteria and not the bacteria themselves, cause illness or merely segments of the pathogen.
Types of Vaccines:
There are mainly six types of vaccines in use. These represent different strategies used to try to reduce the risk of illness while retaining the ability to induce a beneficial immune response.
1. Killed: Some vaccines contain killed, but previously virulent, microorganisms that have been destroyed with chemicals, heat, radioactivity, or antibiotics.
Example: Influenza vaccine, cholera vaccine, polio vaccine, hepatitis vaccine, and rabies vaccine.
2. Attenuated: Some vaccines contain live, attenuated microorganisms. Many of these are live viruses that have been cultivated under conditions that disable their virulent properties, or which use closely
3. Toxoid: Toxoid vaccines are made from inactivated toxic compounds that cause illness rather than the microorganism. Toxoid vaccines are known for their efficacy. All toxoids aren’t for microorganisms.
Example: Croto/usotrox toxoid is used to vaccinate dogs against rattlesnake bites.
4. Subunit: Protein subunit rather than introducing an inactivated or attenuated micro-organism to an immune system, a fragment of it can create an immune response. Subunit vaccine is being used for plague immunization.
Example: Hemagglutinin and neuraminidase subunits of the influenza virus.
5. Conjugate: Certain bacteria have polysaccharide outer coats that are poorly immunogenic. By linking these outer coats to proteins, the immune system can be led to recognize the polysaccharide as if it were a protein antigen. This approach is used in the Haemophilus influenzae type B vaccine.
6. Experimental: A number of innovative vaccines are also in development and in use:
i. Dendrite cell vaccines combine dendritic cells with antigens in order to present the antigens to the body’s white blood cells, thus stimulating an immune reaction. These vaccines have shown some positive preliminary results for treating brain tumors.
ii.. Recombinant vector: It combines the physiology of one microorganism and the DNA of the other, immunity can be created against diseases that have complex infection processes.
iii. DNA vaccine: In recent years, a new type of vaccine called DNA vaccine, created from an infectious agent’s DNA has been developed. It works by insertion of viral or bacterial DNA into human or animal cells.
iv. T-cell receptor peptide vaccines are under development for several diseases using models of Valley fever, stomatitis, and atopic dermatitis. These peptides have been shown to modulate cytokine production and improve cell-mediated immunity.