Why we use serum for viral detection?

Because EDTA or Heparin which added to Violet or Green capped tubes (which gives plasma) affects the viral load, while extraction viral DNA or RNA from Red capped tubes which contain nothing, would give high viral load.

we use serum for viral detection because antigen and antibodies are found on serum not on redblood cells.

the reason use serum for viral is presint antibody free in serum .....

because serum contains antibodies , Antigens & Microorganisms as viruses & bacteria & this  is what we need to search  (Virus it self or its Ab or Ag) & serum not contains RBCs , WBCs  & coagulation factors we not need for them.