|Abstract||Bacillus anthracis must avoid an array of antibacterial defenses by the host during infection. Although anthrax toxin and capsule, located on extra-chromosomal plasmids, play important roles in the pathogenesis of this disease, evidence indicates chromosomal genes also contribute. A random chromosomal mutant library of B. anthracis Sterne was employed to identify novel chromosomal virulence factors. Mutants were screened for loss of virulence in Caenorhabditis elegans. Those unable to infect C. elegans were selected for and the site of transposon insertion was identified. The most highly attenuated mutant had a disruption in an operon containing multiple tellurium resistance genes, leading to an increased susceptibility to potassium tellurite as well as host defenses (ROS and AMPs). In addition, the mutant displays attenuated virulence in whole blood and macrophage survival in comparison to WT. We conclude the tellurium resistance operon of B. anthracis has a novel role in resistance to critical host defenses.