Multiple Ehrlichia chaffeensis genes critical for persistent infection in a vertebrate host are identified as nonessential for its growth in the tick vector; Amblyomma americanum

Ehrlichia chaffeensis is a tick-transmitted monocytic ehrlichiosis agent primarily causing the disease in people and dogs. We recently described development characterization of 55 random mutations E. , which aided defining critical nature many bacterial genes for its growth physiologically relevant canine infection model. In current study, we tested 45 mutants their infectivity ability to pathogen’s tick vector; Amblyomma americanum . Four resulted replication deficiency tick, similar vertebrate host. Mutations defects both hosts included coding predicted alpha/beta hydrolase, putative dicarboxylate amino acid:cation symporter, T4SS protein, membrane-bound proteins. Three caused defective only vector, represented membrane Ten no defect host similarly grew well vector. 28 genes/genomic locations attenuation were recognized as non-essential The metabolic pathway- outer membrane-associated This study documents novel vector- host-specific differences functional gene requirements.