In conclusion, while the rapid progression of plague infections and the severity of the osseous changes observed on the skeleton of EDI064, which are consistent with prolonged illness and multiple infection foci, suggest that the H. influenzae infection was a pre-existing condition, a mechanism such as the pla-mediated inactivation of PAI-1 through Y. pestis could have further contributed to the progression of the H. influenzae infection through interference with the innate immune response and might have led to the rapid perimortem spread of Hib to additional infection foci. This evidence concerns the gene SERPINE1 and infection.