Chapter 13, Problem 1Q

Summary Introduction

(a)

To write:

About serotype-specific immunity.

Introduction:

Immunity can be defined as a condition or state in which body is able to resist any particular infection or disease by counteracting the development of pathogens and preventing them from penetrating the body. Immunity has many weapons that fight against the pathogens.

Explanation of Solution

Some of the pathogens like Streptococcus pneumonia prevail in many antigenically distinct strains called serotypes. The memory B cells and the antibodies produced at the time of infection with one serotype will safeguard the host from reinfection with the similar serotype, however, will not protect against a first infection with a distinct serotype of the similar pathogen, as various epitopes are expressed. Thus, the immunity generated is known as serotype-specific.

Conclusion

In serotype-specific immunity protection is done from reinfection with the same serotype, however, it does not provide protection against the infection with a distinct serotype of the similar pathogen.

Summary Introduction

(b)

To write:

How Streptococcus pneumoniae use serotype-specific immunity to escape detection?

Introduction:

A serovar or serotype refers to a different variation within a species of virus, or bacteria, or between the immune cells of various individuals. These viruses, microbes, or cells are categorized together on the basis of their cell surface receptors, permitting the epidemiologic classification of organisms to the sub-species level.

Explanation of Solution

The Streptococcus pneumoniae has developed about 90 distinct serotypes, which vary in their capsular polysaccharide antigens. A novel infection with a distinct serotype stimulates a new primary response in spite of the more efficient secondary immune response. This is beneficial to the pathogen as it increases the duration of survival in the host, and hence, enhances the chances of transmission to a new host.

Conclusion

Due to the evolution of about 90 kinds of serotypes in Streptococcus pneumoniae, a new infection with a distinct serotype does not instigate efficient secondary immune response, this increases the survival duration of the bacteria, and also increases the probability of transmission to a new host.