# Identifying Wolbachia effectors that facilitate host infection

> **NIH NIH R01** · TRUSTEES OF INDIANA UNIVERSITY · 2020 · $386,485

## Abstract

PROJECT SUMMARY/ABSTRACT
Wolbachia pipientis is an obligate intracellular alpha-proteobacterium that infects 40-60% of insect species on
the planet. Wolbachia infection inhibits RNA virus replication in insects, a phenomenon known as pathogen
blocking. Therefore, Wolbachia infected mosquitos are being released in many parts of the world to control the
spread of human diseases. Importantly, although the mechanism behind Wolbachia’s virus inhibition is not
known, Wolbachia must colonize the host and be efficiently maternally transmitted in order for pathogen
blocking to work. Our long-term goals are to identify the mechanisms used by Wolbachia to establish infection.
To that end, we focus on the type IV secretion system (T4SS), a molecular nanomachine used by Wolbachia to
inject proteins, termed effectors, into the host cellular environment. Via these secreted effectors, the host cell is
modified, allowing Wolbachia to invade and persist.
Our previous work identified and characterized the first secreted effector in Wolbachia (WalE1) and established
an important correlation between T4SS gene expression and expression of secreted effectors. Wolbachia
effectors and the T4SS are upregulated during host pupation. Strikingly, overexpression of WalE1 in
Wolbachia-infected flies facilitated colonization of the developing oocyte and maternal transmission. These
results led to our central hypothesis that Wolbachia uses secreted effectors to establish and maintain host
colonization. Towards this hypothesis, we have identified Wolbachia effectors across the genus, and used a
large-scale growth screen to further identify Wolbachia effectors. We have discovered that many Wolbachia
effectors are clade specific, but many are shared between the insect associated strains. In collaboration with
Peter Christie (UTH), we developed a heterologous secretion assay for Wolbachia effectors, allowing us to
confirm interactions between the type IV coupling protein VirD4 and candidate Wolbachia effectors. Guided by
strong preliminary data, we propose to pursue three Specific Aims to identify and characterize Wolbachia
effectors, and their host targets, using the power of the Drosophila system. We will (1) determine the
Wolbachia secretome, (2) predict effectors and their conservation across Wolbachia infecting insects, and (3)
identify host targets and effectors that facilitate infection by Wolbachia.
Studies of Wolbachia - host interactions are still in their infancy despite the recognized contributions of
endosymbiotic associations to insect reproduction and evolution, and the ability to alter vector competence.
These proposed studies will significantly advance our understanding of how Wolbachia employs its T4SS to
establish infection, a necessary prerequisite to pathogen blocking.

## Key facts

- **NIH application ID:** 9927992
- **Project number:** 5R01AI144430-02
- **Recipient organization:** TRUSTEES OF INDIANA UNIVERSITY
- **Principal Investigator:** Irene Newton
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $386,485
- **Award type:** 5
- **Project period:** 2019-05-10 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9927992

## Citation

> US National Institutes of Health, RePORTER application 9927992, Identifying Wolbachia effectors that facilitate host infection (5R01AI144430-02). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/9927992. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*