Answer:
To gather relevant knowledge about their origin and to determine if the strain has been genetically modified.
Explanation:
A researcher researching with the anti-bioterrorism working group, they are required to assess certain blood specimens only for existence of Yersinia pestis, the organisms which causes the disease.
Since verifying that perhaps the varieties showed Y. Pestis, they are instructing their group to start sequence alignment the strains. So, this is to collect specific knowledge about their origin and to assess if the strain has also been genetically modified.