Question

1. Explain how a vaccine can induce a secondary response to a viral infection.

Answer 1

Vaccination is very important for protection of our body from infection caused by pathogens like bacteria,viruses.. etc. As we know our body has a defence system for fighting against these pathogen called Immune system.It can provides two level of immunity to the body such as innate immunity and adaptive immunity.Innate immunity is present in our body by birth and it gives first line of defence such as from skin barrier,mucus, lysozyme etc.. Adaptive immunity gives immune response by second line of defence which includes Vaccination...

Our immune system has ability to differentiate between own cell and foreign cells or body ( antigen) called Antigen differntiating ability.As we know each pathogen has their own unique composition ( antigen) and when enters into the body, immune response were shown...this response is called primary response as our body first time producing antibody against this antigen.

The primary response shows slow response because our immune system is not aware of antigenic reaction ability of the pathogen,it will take time to produce antibody which results into production of disease in the body but after sometime when the same pathogen enters into our body , immune response is very quick because they are familier with the properties of antigen, as they detect pathogen by memory cells in the immune system..and able to destroy the pathogen by producing antibodies against antigen and protect the body from infection/ disease.This property of immune system is comes under adaptive immunity. The vaccine has same effects as secondary response.

Vaccine also works as secondary response because in vaccination the composition of antigen were provided, in which vaccinated cells has memory cells for that antigen and when the live pathogen will enter into the body with same antigenic composition ,vaccinated cells able to recognise them with there memory cells and produce antibodies rapidly ,to destroy the pathogen before pathogenic reproduction and infection / disease.

Vaccine secondary response will protect the cells from pathogens ,as they detect the antigen(from memory cells production ),attacked them by producing antibodies and finally destroy them before causing disease. The main function of vaccines is to produce memory cells against pathogen which automatically results into production of antibodies very rapidly before pathogenic reproduction.

(There are normally two types of vaccine used... active vaccination and passive vaccination .In active immunization body itself produce antibodies as stimulated by vaccine after exposure of pathogen ,it is slow but provides protection to body long term..only one dose is sufficient for immunity On the contrary in passive immunization ,the antibodies were injected through vaccine ,body will not produce it .It has short term effect and various doses were required for protection against disease .eg.vaccines for rabies, tetanus etc. )

In viral infections,vaccinated cells first detect the virus by their memory cell response ,after that they produce antibodies against that virus and finally destroy them before virus reproduce and cause disease.Due to secondary response of vaccines,viral infections not caused because antibiodies production is as faster as viruses reproduction and immune cells able to destroy viruses very quickly...