title: Immunity in heifers 12 months after vaccination with a multivalent vaccine containing a United States Leptospira borgpetersenii serovar Hardjo isolate.
abstract: OBJECTIVE
  To evaluate immunity induced by a multivalent vaccine containing a US Leptospira borgpetersenii serovar Hardjo type hardjo bovis (LHB) isolate in heifers challenged 12 months after vaccination.
  
  
  METHODS
  Prospective vaccine challenge study.
  
  
  METHODS
  36 one-month old Holstein heifers.
  
  
  METHODS
  18 heifers were vaccinated at 4 and 8 weeks of age with an inactivated vaccine containing Leptospira fractions. Additionally, 18 heifers were vaccinated at the same age with the same vaccine without any Leptospira fractions. All heifers were challenged with a US-origin LHB 12 months following booster vaccination. Urine samples were collected weekly for 8 weeks after challenge, and serum was collected at -1, 28, and 56 days after challenge for serologic testing. At 8 weeks after challenge, all heifers were necropsied, and kidney and reproductive system samples were collected for bacteriologic culture.
  
  
  RESULTS
  4 of 18 vaccinates had positive results of bacteriologic culture of urine samples, but only at 1 time point. All control heifers had positive results of bacteriologic culture of urine samples for at least 5 time points. Vaccinates had negative results of bacteriologic culture of kidney and reproductive system samples following necropsy, whereas all control heifers had positive results of bacteriologic culture of kidney samples and 5 of 18 had positive results of bacteriologic culture of reproductive system samples.
  
  
  CONCLUSIONS
  The vaccine administered to calves at 1 month of age prevented leptospire colonization of kidney and reproductive system tissue and significantly reduced urine shedding following challenge 12 months after vaccination. This vaccine provides an opportunity to protect calves at an early age from becoming infected and ultimately from becoming an LHB reservoir.
authors.affiliation: Rural Technologies Inc, 1008 32nd Ave, Brookings, SD 57006, USA. azimmerman@ruraltechinc.com
authors.forename: Alicia D
authors.initials: AD
authors.lastname: Zimmerman
authors.forename: Eric W
authors.initials: EW
authors.lastname: Springer
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Barling
authors.forename: Robin E
authors.initials: RE
authors.lastname: Buterbaugh
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Pooley
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Scholz
authors.forename: James R
authors.initials: JR
authors.lastname: Rhoades
authors.forename: Christopher C L
authors.initials: CC
authors.lastname: Chase
mesh_terms: D000818:Animals; D057138:Bacterial Shedding; D001428:Bacterial Vaccines / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D006801:Humans; D007919:Leptospira / Q000276:immunology*; D007922:Leptospirosis / Q000517:prevention & control / Q000662:veterinary*; D014551:Urinary Tract / Q000382:microbiology
chemical_list: D001428:Bacterial Vaccines