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ARS Home » Research » Publications at this Location » Publication #179817
Title: ANTIBACTERIAL EFFECT OF BACTERICIDAL/PERMEABILITY-INCREASING PROTEIN (BPI)-DERIVED SYNTHETIC PEPTIDE AGAINST MAJOR GRAM-NEGATIVE MASTITIS PATHOGENS.

Author
item CHOCKALINGAM, ANNAPOORANI - PENN STATE UNIVERSITY
item Paape, Max
item Bannerman, Douglas

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2005
Publication Date: 5/12/2005
Citation: Chockalingam, A., Paape, M.J., Bannerman, D.D. 2005. Antibacterial effect of bactericidal/permeability-increasing protein (bpi)-derived synthetic peptide against major gram-negative mastitis pathogens [abstract]. BARC Poster Day.

Interpretive Summary:

Technical Abstract: Incidence of clinical mastitis due to Gram-negative bacteria such as Escherichia coli (E.coli) and Klebsiella spp, are high in dairy cows during early lactation. Gram-negative bacteria account for nearly 40% of clinical mastitis cases and the estimated loss to the U.S. dairy industry is $800 million per year. Endotoxin, an integral component of the cell wall of all Gram-negative bacteria, activates host innate immunity and induces production of pro-inflammatory mediators. However, prolonged or excessive inflammatory responses are detrimental to host mammary tissue. Death resulting from acute mastitis is most often associated with Gram-negative bacteria intramammary infection and the subsequent development of septic shock. Despite advances in management practices, the incidence of mastitis due to E.coli remains unchanged. Further, current antimicrobial therapy remains suboptimal for the treatment of these infections. The goal of our research is to develop novel endogenous therapeutics that have potential antimicrobial and anti-inflammatory effects against Gram-negative intramammary infections. BPI.30, a synthetic fusion peptide of two different domains of BPI protein, was evaluated for its bactericidal activity against various strains of clinical isolates of Gram-negative mastitis pathogens. It exhibited complete bactericidal activity against E.coli P4 strain at 10ug/ml in serum and broth and was shown to have significant growth inhibitory effects at 1ug/ml. The biological activity of the peptide was also tested in milk and whey, two important biological fluids in mastitis. In whey, the peptide exhibited bactericidal activity at 100 ug/ml and significant growth inhibition at 10 and 1 ug/ml. However, in milk it was found to have only an inhibitory effect, not a bactericidal effect, against the growth of E.coli. We hypothesized that cations in milk like Ca++ and Mg++ could have an inhibitory effect against the biological activity of BPI. In the presence of EDTA (16mM), a metal chelator, BPI.30 had bactericidal activity at 10 ug/ml in milk. Further studies will test its potency as an anti-inflammatory molecule by determining its LPS binding/neutralization activity. These data suggest that the BPI.30 synthetic peptide may be an effective antimicrobial for the treatment of Gram-negative infections in cattle. Supported by USDA ARS CRIS Project No. 1265-32000-065.