The treatment of snake-bite by antivenom is an example of

The secretion of interferon is inhibited by . . . . . . .

In which of the following organs do immature lymphocytes differentiate into antigen-sensitive lymphocytes?

$A$ substance (low molecular weight protein) produced by host cells in response to viral infection that protects other cells against further viral infection is:

Which of the following statements are correct regarding the structure and types of antibodies in humans?
$i$. Antibodies are also called Immunoglobulins that are produced as an immune response to antigenic stimulation.
$ii$. They are produced by all types of $T$-lymphocytes and $B$-lymphocytes.
$iii$. An antibody is a $Y$-shaped molecule formed of four polypeptide chains. Antibodies present in plasma determine many blood group systems like $ABO$,$Rh$,$P$,$MNS$ etc.
$iv$. An antibody molecule consists of two antigen-binding sites called paratopes.

In which type of acquired immunity are microbes or infectious organisms deliberately introduced into the host?