The WHO classifies plague as a “re-emerging disease” because the bacillus Yersinia pestis has resurfaced in certain parts of the world, particularly in Africa and in countries of the former USSR. The Democratic Republic of the Congo and Madagascar are among the list of new outbreaks. In addition, two cases were detected in the United States in June 2012, two cases in Algeria in 2003 and 2008, and several cases were reported in Libya in 2009. The principal modes of transmission of plague are rodents and fleas. Moreover, plague is classified by the CDC [1] as a category A agent, in its list of agents that could be used as bioterrorism weapons.

For these reasons, it is important to have available rapid tests for environmental detection of Yersinia pestis. To meet this objective, anitbodies must be developed that can detect a protein fulfilling different criteria. This protein must be specific to Yersinia pestis, exposed at the surface of the bacteria, expressed well at 20° C, and involved in the virulence of the bacteria. Monoclonal antibodies directed against the protein PLA (Plasminogen Activator), which meet these specifications, were produced and characterized. Two types of tests were then developed: a rapid detection test with dipsticks for quick and easy use in the field (PLA-dipstick), and an enzyme immunoassay test used in the laboratory (PLA-EIA). Both tests showed a very good specificity (no recognition of strains close to Yersinia pestis), and a good sensitivity [2]. These tests could also be used to evaluate the infectivity of fleas (the vector of plague), and for diagnosis in humans.

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[1] Centers for Disease Control and prevention
[2] The detection limit is 2.105 cfu/ml for the PLA-EIA test, and 106 cfu/dipstick for the PLA-dipstick test, for Yersinia pestis grown at 20° C