Submitted to: International Virtual Conference on Infectious Diseases of Animals
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 1997
Publication Date: N/A
Technical Abstract: A polymerase chain reaction (PCR)-based diagnostic test for Leptospira interrogans (sensu lato) serovars was developed based on the multi-copy insertion sequence IS1533. Sequences related to IS1533 are found throughout the different genetic groups of L. interrogans (sensu lato). This element can range in number from zero to approximately 60 copies per genome. The PCR assay amplified DNA from 62 of 180 pathogenic leptospiral serovars. No amplification was detected with DNA from non-pathogenic leptospires or spirochetes belonging to the genera Borrelia, Serpulina, or Treponema. Using the PCR assay, leptospiral DNA was detected in the urine of both non-vaccinated and vaccinated cattle experimentally infected with L. interrogans (sensu lato) serovar hardjo type hardjobovis. Analysis of serial ten-fold dilutions of processed (concentrated) urine samples yielded detectable product using the equivalent of about 1.5 ul to 150 ul of unconcentrated urine. This is the equivalent to detection of between 1 an 10 cells, or about 40 to 400 copies of the target sequence. The intensity and ability to detect product varied among different infected animals during a ten-week infection, suggesting that urinary shedding of leptospires may be episodic.