Investigating the allelic determinants of immunological natural variation in Drosophila melanogaster. Alejandra Guzman, David Schneider. Microbiology and Immunology, Stanford University, Stanford, CA.

   Immunity consists of at least two branches: resistance, the hosts ability to control pathogen number, and tolerance, the hosts ability to neutralize the infections pathology. Immune natural variation increases the fitness of a population because, as a whole, the population can better respond to a wider range of pathogens and environmental conditions. In 2004, Lazzaro et. al showed that in D. melanogaster there are polymorphisms in the regions surrounding previously described immunity genes. Our work used an unbiased approach to discover alleles responsible for the natural variation in D. melanogaster immunity. Here, we screened 115 of the 192 fully sequenced inbred D. melanogaster lines derived from a single population in North Carolina called the Drosophila Genetic Reference Panel (DGRP). We infected these homozygous lines with Listeria monocytogenes and measured changes in fly survival and bacterial growth. Using ANOVAs we found polymorphisms that significantly (p <10-6) correlated with changes in immunocompetence. These polymorphisms were in close proximity to 153 genes. Roughly 10% of these genes are ion channels; we are currently investigating the role ion-channels during infection.