NEET BIOLOGY

Detailed explanation-1: -An acute viral infection is characterized by sudden or rapid onset of disease, which can be resolved quickly by robust innate immune responses exerted by the host or, instead, may kill the host.

Detailed explanation-2: -Humans have three types of immunity-innate, adaptive, and passive: Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. For example, the skin acts as a barrier to block germs from entering the body.

Detailed explanation-3: -There are four characteristics of adaptive immunity: antigenic specificity, diversity, immunologic memory and ability to distinguish between self and non-self. An immune response involves Lymphocytes (B-cells and T-cells) and antigen presenting cells (macrophages, B-cells, and dendritic cells).

Detailed explanation-4: -pathogen recognition by cells of the innate immune system, with cytokine release, complement activation and phagocytosis of antigens. the innate immune system triggers an acute inflammatory response to contain the infection. meanwhile, antigen presentation takes place with the activation of specific T helper cells.