Question

One of the reasons for inability to produce an effective vaccine for colds may be

• A. It cannot be handled in laboratory conditions
• B. It constantly changes its surface antigen
• C. The chemical nature of virus is such that no substance can act against it
• D. It has novel nitrogenous bases in its sequence

Answer 1

The correct option is B It constantly changes its surface antigen

A number of viruses escape immune attack by constantly
changing their surface antigens. The rhinovirus virus is a
prime example. Antigenic variations among rhinovirus is one of the reasons why effective vaccine against all strains has not been developed. Other types of cold can also be caused by at least 200 different viruses including adenoviruses, coronaviruses, parainfluenza, and rhinoviruses, etc. Rhinoviruses account for up to 75 percent of colds in adults. There are at least 160 different strains, or serotypes, of rhinoviruses alone.