ALDH7A1 and susceptibility to pneumonia measurement: Additionally, both high and low levels of intracellular c-di-AMP have been shown to be detrimental for bacterial survival in vivo, as deleting both PDE genes in S. pneumoniae attenuates bacterial virulence in a mouse pneumonia model of infection (52), although low levels of c-di-AMP attenuate the virulence of L. monocytogenes in both bone marrow-derived macrophages and in a mouse model (23).