HTRA1 and anthrax infection: Disruption of the htrA gene in toxinogenic B. anthracis Vollum (pXO1+; pXO2+) or Sterne (pXO1+; pXO2-) strains resulted in a dramatic attenuation in the guinea pig, murine and rabbit models of anthrax (Chitlaru et al., 2011b, 2016).