Draft genome

Here is the latest paper on bubonic plague and the Black Death, from just a few months ago:
A draft genome of Yersinia pestis from victims of the Black Death
Although the study confirmed the basic story from last year - that the bacteria that caused the Black Death was the ancestor of all modern bubonic plague strains - it did not find any obvious change in virulence genes that might account for the huge mortality that the Black Death caused.

'(W)e posit that molecular changes in pathogens are but one component of a constellation of factors contributing to changing infectious disease prevalence and severity, where genetics of the host population, climate, vector dynamics, social conditions and synergistic interactions with concurrent diseases should be foremost in discussions of population susceptibility to infectious disease and host–pathogen relationships with reference to Y. pestis infections.'