Chapter 18, Problem 1R

Which could cause the disease it is supposed to prevent?

1. a. attenuated measles virus
2. b. dead Rickettsia prowazekii
3. c. Vibrio cholerae toxoid
4. d. hepatitis B antigen produced in yeast cells
5. e. purified polysaccharides from Streptococcus pyogenes
6. f. Haemophilus influenzae polysaccharide bound to diphtheria toxoid
7. g. a plasmid containing genes for influenza A protein

Summary Introduction

Introduction:

Vaccine is used to prevent the disease. Vaccine are classified into following types: live attenuated vaccine, inactivated vaccine, toxoids, subunit vaccine, and conjugated vaccine. It can also be produced by the recombinant technology.

Explanation of Solution

1. a. Live attenuated vaccine: The antigenicity of the pathogen is minimized and the live microbes are injected into humans. Antibodies are produced by the host against microbes. These antibodies prevent the infection caused by that specific virus in the host. For example, live attenuated measles virus. However, the attenuated strain of microbe in this type of vaccine may regain pathogenicity through mutations. In such cases, it may cause the disease for which this vaccine is used to prevent.
2. b. Inactivated vaccine: In this type of vaccine, killed pathogen is into the patient and it is less effective. However, using this type of pathogen in live attenuated form, it may cause serious problems. It often needs a booster dose. For example, dead Rickettsia prowazekii.
3. c. Subunit inactivated toxoid vaccine: Inactivated toxin are used to prevent disease that are known to be caused by toxins. In this type, the cells of microbes are not introduced into the human body. They need a booster dose after some period of time. For example, Vibrio cholera toxoid.
4. d. Subunit vaccine: Antigenic portions of an antigen are injected into the patients, which cannot undergo replication. It is also termed as recombinant vaccine and it undergo better stimulation of the immune response. For example, Hepatitis B antigen produced in yeast cells and purified polysaccharides from Streptococcus pyogenes.
5. e. Conjugated vaccine: Proteins combined with polysaccharides to fight against antigens of pathogenic microbes. It is used in children to give a strong immune response. For example, Haemophilus influenzae polysaccharides bound to diphtheria toxoid.
6. f. DNA Vaccine: It is otherwise known as nucleic acid vaccine. It is still carried out in the experimental phase and not in practice. Here, the recombinant plasmid is isolated and injected into humans. This undergo gene expression and synthesize antigens that are specific in preventing the disease. For example, a plasmid containing influenza A protein.

Conclusion

Disease is prevented by gaining the antibodies by administering the attenuated live microbe, dead pathogens, or toxoids. Such vaccines could prevent the infection that occurs for the next time.