Scientists Discover Why Plague Is So Lethal
Pastor Dale Morgan
Scientists Discover Why Plague Is So Lethal*
Bubonic plague has killed over 200 million people.
by Staff Writers
London, UK (SPX) May 05, 2008
Bacteria that cause the bubonic plague may be more virulent than their
close relatives because of a single genetic mutation, according to
research published in the May issue of the journal Microbiology.
"The plague bacterium Yersinia pestis needs calcium in order to grow at
body temperature. When there is no calcium available, it produces a
large amount of an amino acid called aspartic acid," said Professor
Brubaker from the University of Chicago, USA. "We found that this is
because Y. pestis is missing an important enzyme."
Bubonic plague has killed over 200 million people during the course of
history and is thus the most devastating acute infectious disease known
to man. Despite this, we are still uncertain about the molecular basis
of its extraordinary virulence.
"Y. pestis evolved from its ancestor Y. pseudotuberculosis within the
last 20,000 years, suggesting its high lethality reflects only a few
genetic changes. We discovered that a single mutation in the genome of
Y. pestis means the enzyme aspartase is not produced," said Professor
Brubaker.
Aspartase is present in almost all bacteria but it is curiously absent
in many pathogenic types. These include mycobacteria that are pathogenic
to man, Francisella tularensis and rickettsiae (both of which cause
diseases transmitted to humans via insects). "This suggests that the
absence of aspartase may contribute to serious disease," said Professor
Brubaker.
Aspartase digests aspartic acid. Because Y. pestis doesn't have the
enzyme, it produces much more aspartic acid than is required by the
person infected. This may cause an imbalance to the host amino acid
pools. "If this is the case then we might be able to reduce the death
rates of these diseases by developing a treatment that removes some of
the extra aspartic acid," said Professor Brubaker.