In mammals, histamine is secreted by

Except skin, other physical barriers which also helps to prevent the entry of the microorganisms are

$I.$ mucus coating of the epithelium lining the respiratory

$II.$ gastrointestinal tracts

$III.$ urogenital tracts

Choose the correct option

AIDS related complex $(ARC)$ is a disease which leads to fever, swollen lymph nodes, night sweats, loss in weight etc. represents

Nobel Prize for medicine was given for confirming the role of Helicobacter pylori in causing

‘Tuberculosis' is caused by

Infectious proteins are present in