A Tractable Drosophila Cell System Enables Rapid Identification of Acinetobacter baumannii Host Factors.

Qing-Ming Qin,Allison Rice-Ficht,Gabriel Gomez,Paul De Figueiredo,Jianwu Pei,Thomas A Ficht

doi:10.3389/fcimb.2020.00240

Abstract

Acinetobacter baumannii is an important causative agent of nosocomial infections worldwide. The pathogen also readily acquires resistance to antibiotics, and pan-resistant strains have been reported. A. baumannii is widely regarded as an extracellular bacterial pathogen. However, accumulating evidence demonstrates that the pathogen can invade, survive or persist in infected mammalian cells. Unfortunately, the molecular mechanisms controlling these processes remain poorly understood. Here, we show that Drosophila S2 cells provide several attractive advantages as a model system for investigating the intracellular lifestyle of the pathogen, including susceptibility to bacterial intracellular replication and limited infection-induced host cell death. We also show that the Drosophila system can be used to rapidly identify host factors, including MAP kinase proteins, which confer susceptibility to intracellular parasitism. Finally, analysis of the Drosophila system suggested that host proteins that regulate organelle biogenesis and membrane trafficking contribute to regulating the intracellular lifestyle of the pathogen. Taken together, these findings establish a novel model system for elucidating interactions between A. baumannii and host cells, define new factors that regulate bacterial invasion or intracellular persistence, and identify subcellular compartments in host cells that interact with the pathogen.

Highlights

Acinetobacter baumannii is a clinically important pathogen that can survive on hospital equipment and can cause serious nosocomial infections
We previously demonstrated that mammalian orthologs of hits, e.g., IRE1a, a key unfolded protein response (UPR) sensor of endoplasmic reticulum (ER) stress, and autophagy related proteins, identified in RNAi (RNA interference) screens of the Drosophila S2 cells for host factors mediating pathogen infection are important for bacterial and fungal infection of mammalian cells, thereby validating the utility and convenience of this insect cell model for host-pathogen interaction studies (Qin et al, 2008, 2011; Pandey et al, 2018)
The levels of bacterial invasion was significantly lower in these cells compared to J774 cells, a murine macrophage-like line that has been previously shown to be susceptible to invasion by A. baumannii (Asplund et al, 2013; May et al, 2019)

Summary

Introduction

Acinetobacter baumannii is a clinically important pathogen that can survive on hospital equipment and can cause serious nosocomial infections. In the past two decades, progress has been made in identifying and characterizing host factors that regulate the intracellular lifestyle of diverse pathogens, including A. baumannii (Choi et al, 2008; Smani et al, 2012; Rumbo et al, 2014; Wang et al, 2016; Parra-Millan et al, 2018; An et al, 2019). This aspect of the infection process remains poorly understood

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