**5. Markers of infectious diseases**

In the recent decades extensive research has been conducted to understand the regulation of immune system in *Drosophila melanogaster*. Using techniques like genome wide screens, *Drosophila* S2 cell line in-vitro models and tissue specific loss of function mutation in transgenic GAL4/UAS fly allows studying selective pathways of immune response [56]. Up-regulation of antimicrobial peptides (AMP) in flies during bacterial and fungal infection was frequently observed, these six AMP genes expression level could be analyzed in flies [42, 57]. ROS level in flies trigger several pathways responsible for tolerance (cell survival) and apoptosis (cell death) could be assayed in virally infected flies [49, 50]. Rescue of diseased transgenic flies upon feeding of desired drug could reveal drug efficacy [56]. Survival of flies would further reveal the effect of drugs during an ongoing pathogenesis [58].
