Chapter 16, Problem 1Q

Summary Introduction

Introduction:

A virus is a small infectious agent that cannot be seen through the naked eyes. Viruses are made up of protein coat in which their genetic material is present. The viruses contain either double stranded or single stranded DNA or RNA as their genetic material. Based on their genetic material David Baltimore classified viruses into seven different classes.

Answer to Problem 1Q

Correct answer:

Herpes virus is the infectious agent that has evolved to maintain a persistent state in its host.

Therefore, option (b) is correct.

Option (b) is given as “herpes virus”.

Explanation of Solution

Justify the reason for the correct statement:

Human herpes virus 3 is the causative agent of chickenpox. Herpes virus enters into the respiratory mucosa, and from there it enters the bloodstream. This condition is called as viremia. From the blood, the virus can enter into the skin, and produce its characteristics lesion. Through blood, the virus can enter into the sensory nervous system and the dorsal root of ganglia. In ganglia of the host cell, the virus can persist there for a long time and escape from host cell immunity.

Hence, option (b) is correct.

Justify the reasons for the incorrect statements:

Option (a) is given as “Variola virus”.

Variola virus does not have the ability to persist in a host cell. Hence, it is a wrong answer.

Option (c) is given as “vaccinia virus”.

Vaccinia virus does not have the ability to persist in a host cell. Hence, it is a wrong answer.

Option (d) is given as “Staphylococcus aureus”.

S. aureus does not have the ability to persist in a host cell. Hence, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.

Conclusion

Human herpes virus has an ability to remain latent in a host cell.