Immune assays – Department of Biology - University of Copenhagen

Immune assays provide ways of measuring the innate immune response of insects to pathogens and other antigens. From samples of haemolymph, we can measure:

  • Number of haemocytes (blood cells)
  • Activity against specific bacteria via zone-of-inhibition assays
  • Amount of the key enzyme phenoloxidase and its precursor pro-phenoloxidase, that is used by the insect immune system

We can also estimate encapsulation response, which measures melanin deposition on an alien body (typically a piece of nylon inserted into the insect to mimic a real endoparasite) as a proxy of immune response.

The extent to which the expression of antimicrobial peptides such as abaecin and defensin are up-regulated, either after infection with pathogenic fungi, or prophylactically, can also be used to investigate immune responses and trade-offs between immunocompetence and other life-history traits.

What are they used for?

We use immune assays to answer questions such as:

  • How and why do individual ants differ in their immune responses?
  • Does immune defence vary according to sex and task within the colony?
  • Do mating and sperm storage carry a cost for the immune system of queens?
  • Do social parasites also exploit the immune systems of their hosts, and down-regulate their own immune systems?
  • How behaviours, antibiotics produced by symbionts and chemical defences within social insect colonies can provide alternatives to individual immune systems.

Organisms

Fungus-growing antsHoney beesLycaenid butterfliesMyrmica ants; Pathogenic fungiGarden ants