Bacteria Genomes - BRUCELLA MELITENSIS

Comparison of the closely related Brucella suis and Brucella melitensis genomes has defined a finite set of differences that could be responsible for the differences in virulence and host preference between these organisms. Based on the genomic and functional similarities between Brucella suis and organisms from the Rhizobium/Agrobacterium group it seems likely that the Brucella evolved from a soil/plant-associated ancestral bacteria.

Brucella are the etiological agents of brucellosis, a zoonotic disease endemic in many areas of the world, characterised by chronic infections in animals leading to abortion and infertility, and a systemic, febrile illness in humans. Human infection frequently occurs via direct contact with tissues and fluids from infected animals, but can also be contracted by consumption of contaminated foods or by inhalation.

Brucella melitensis is a Gram-negative, aerobic, facultative intracellular bacterial pathogen that causes abortion in goats and sheep and Malta fever in humans. Sir David Bruce, a British army surgeon, discovered the organism in 1887 as the causative agent of Malta fever. It now bears his name coupled with melitensis, which is Latin for Malta The most prominent symptoms are weakness and intermittent fever. The disease persists for months if left untreated but is seldom fatal in humans. Infection is normally by inhalation and via abraded skin, and transmission between species occurs readily. Humans usually become infected by ingestion of affected milk.

B. melitensis is prevalent in Mediterranean and Middle Eastern countries through Central Asia to China and southern areas of the former Soviet Union. Some areas of Africa and India, as well as Central and South America are affected. In the UK, Brucella melitensis was originally made notifiable by the Brucella Melitinsis Order of 1940 (as amended).

Brucella melitensis is considered a potential agent for biological warfare by the US Center for Disease Control and Prevention and rated 'B' on the list of potential bioterrorist weapons. Although brucellosis is rarely fatal for humans, it is highly contagious, difficult to treat, and spreads easily. So far, a vaccine has not yet been discovered to fight the disease in humans, and animal vaccines are pathogenic to humans.

The genome of B. melitensis strain 16M was sequenced and found to contain 3,294,935 bp distributed over two circular chromosomes Sequence analysis has confirmed that Brucella melitensis has the ability to survive and grow in aerobic, microaerophilic, or anaerobic conditions.

References:

Proc Natl Acad Sci U S A 99(1):443-448(2002)
http://gnn.tigr.org/articles/01_02/Brucella.shtml
www.medinfo.ufl.edu/year2/mmid/ bms5300/bugs/brucella.html
http://www.defra.gov.uk/animalh/diseases/notifiable/disease/brucella_melitensis.htm