Type II secretion system (T2SS) plays an important role in pathogenesis of bacterial infections. In this multiprotein machinery, the outer-membrane secretin protein PulD, is a channel by which effectors are secreted into host environment. We found there is a difference in the death rate of macrophages challenged by PulD knocked out strains compared to the wild type Klebsiella pneumoniae. In the proposed study, we are preparing to explore whether PulA, the only identified secreted protein of T2SS in K. pneumoniae, is the reason for this observed difference in the PulD knockout. Furthermore, to identify potential novel T2SS effectors which may be playing a role in macrophage killing, we will also use a machine learning approach to generate a trained model predicting and validating new effectors of the T2SS in K pneumoniae.