Poster Presentation International Pasteurellaceae Conference 2014

Bovine lactoferrin effects against Mannheimia haemolytica A1 (#67)

Maria Luisa Samaniego Barron 1 , S. Luna-Castro 1 , F. Suarez Gaemes 2 , G.M. De la Garza Amaya 1
  1. Cell Biology, Research Centre and Advanced Studies (CINVESTAV-IPN), Mexico City, Mexico
  2. Microbiology, National Autonomous University of Mexico (UNAM), Mexico City, Mexico

Mannheimia haemolytica (Mh) is the principal bacterial species in the bovine respiratory disease complex. This disease causes losses of almost 1 billion dollars in the USA2 3 4 . Mh is an opportunistic pathogen, thus the bacteria are always in contact with bovine defenses, like lactoferrin. Lactoferrin (Lf) is a glycoprotein present in milk, colostrum, and mucosal secretions and is secreted by neutrophils in infection sites5 . Bovine apo-Lf (BapoLf) (iron-free) possesses bacteriostatic and bactericidal properties. Interestingly, BapoLf is able to synergize with antibiotics1 .

Mh strain used was obtained from a bovine pneumonic lung. Firstly, we probed whether Mh uses the iron-saturated bovine Lf (BholoLf) as an iron source, and then BapoLf was tested for bactericidal property. Also, overlay assays were made to identify Mh Lf-binding proteins in outer membrane.

Mh was not able to grow in BholoLf as a sole iron source, even to an iron concentration of 60 µM, when 300 µM 2´2 dipyridyl was used to chelate the iron; FeSO4 or FeCl3 (25 and 20 µM) were added as positive controls of growth. BapoLf inhibited the Mh growth since a concentration of 3.5 µM and with 13 µM BapoLf the viability was reduced approximately 90%. In addition, bactericidal effect of BapoLf increased when combined with oxitetraciclin; other antibiotics are being tested. We purified an OMP of 40 kDa as a Mh BapoLf binding protein; the identification by MALDI-TOF will be used. The results encourage us to study the BapoLf bactericidal mechanism affecting the Mh outer membrane and its use in the treatment of bovine mannheimiosis. Probably, early weaning of animals does not allow their defense against this bacterium. When an infection by Mh is established, BapoLf could be used to improve the treatment with antibiotics.

The first author is a doctorate student at Cinvestav-IPN, scholarship no. 207444 Conacyt, Mexico.

  1. Beddek, A. J. and A. B. Schryvers (2010) "The lactoferrin receptor complex in Gram negative bacteria." Biometals 23(3): 377-86.
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  3. Whiteley, L. O., S. K. Maheswaran, et al., (1992). "Pasteurella haemolytica A1 and bovine respiratory disease: pathogenesis." J Vet Intern Med 6(1): 11-22.
  4. Rice, J. A., L. Carrasco-Medina, et al., (2007). "Mannheimia haemolytica and bovine respiratory disease." Anim Health Res Rev 8(2): 117-28.
  5. Adlerova, L., A. Bartoskova, et al., (2008). "Lactoferrin: a review." Veterinarni Medicina 53(9): 457-468.