NEET BIOLOGY

Detailed explanation-1: -In humans, any cell that a pathogenic organism can invade is a host cell, e.g., human immune cells like CD4+ cells and macrophages are the host cell for HIV. It is essential to understand that only certain species of hosts or certain cells can serve as hosts for viruses or bacteria.

Detailed explanation-2: -Viral Structure. In the simpler viruses the virion consists of a single molecule of nucleic acid surrounded by a protein coat, the capsid; the capsid and its enclosed nucleic acid together constitute the nucleocapsid. In some of the more complex viruses the capsid surrounds a protein core (Fig.

Detailed explanation-3: -Based on their host, viruses can be classified into three types, namely, animal viruses, plant viruses, and bacteriophages.