# Insect immune specificity in a host-parasite model

## TL;DR

This study explores how bumblebees respond genetically to a trypanosome infection, revealing immune pathways and gene interactions.

## Contribution

The study identifies Dscam gene differential expression linked to host-parasite genotype interactions in bumblebees.

## Key findings

- Many immune-related genes are differentially regulated in infected bumblebees.
- An interaction between the peritrophic membrane and immune system is suggested.
- Dscam gene expression varies based on host-parasite genotype interactions.

## Abstract

Ecological studies routinely show host-parasite genotype-genotype interactions in insect systems. The mechanisms behind these interactions are not clearly understood. Using the bumblebee Bombus terrestris / trypanosome Crithidia bombi model system, we have carried out a transcriptome-wide analysis of gene expression in bees during C. bombi infection. We have performed three analyses, 1) comparing expression in infected and non-infected bees 24 hours after infection by Crithidia bombi, 2) comparing expression at 24 and 48 hours after C.bombi infection and 3) most importantly searching for differential gene expression associated with the host-parasite genotype-genotype interaction at 24 hours after infection. We found a large number of genes differentially regulated related to numerous canonical immune pathways. These genes include receptors, signaling pathways and effectors. We discovered a possible interaction between the peritrophic membrane and the insect immune system in defense against Crithidia. Most interestingly we found differential expression of Dscam related transcripts depends on the genotype-genotype interactions of the given bumblebee colony and Crithidia strain.