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  • Author or Editor: Dante S. Zarlenga x
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Abstract

Objective—To evaluate antimicrobial activity of bovine bactericidal permeability–increasing protein (bBPI)–derived synthetic peptides against mastitis-causing gram-negative bacteria.

Sample Population—Bacterial isolates from the milk of cows with clinical mastitis.

Procedures—3 peptides were synthesized with sequences corresponding to amino acids 65 to 99 (bBPI65–99) or 142 to 169 (bBPI142–169) or the combination of amino acids 90 to 99 and 148 to 161 (bBPI90–99,148–161) of bBPI. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these peptides against bacterial isolates from cows with mastitis were determined by use of a standardized broth microdilution assay. The ability of these peptides to retain their antimicrobial activity in serum and milk was also evaluated. Finally, bacterial lipopolysaccharide (LPS)-neutralizing activity of these peptides was assayed with the Limulus amebocyte lysate test.

Results—Of the 3 peptides tested, bBPI90–99,148–161 had the widest spectrum of antimicrobial activity, with MIC and MBC values ranging from 16 to 64 Mg/mL against Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp and from 64 to 128 Mg/mL against Pseudomonas aeruginosa. None of the peptides had any growth-inhibitory effect on Serratia marcescens. The antimicrobial activity of bBPI90–99,148–161 was inhibited in milk, but preserved in serum. Finally, bBPI142–169 and bBPI90–99,148–161 completely neutralized LPS.

Conclusions and Clinical Relevance—bBPI90–99,148–161 is a potent neutralizer of the highly proinflammatory molecule bacterial LPS and has antimicrobial activity against a variety of gram-negative bacteria. The ability of bBPI90–99,148–161 to retain antimicrobial activity in serum suggests a potential therapeutic application for this peptide in the management of gram-negative septicemia.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize cytokine messenger RNA (mRNA) expression in intranasally vaccinated calves after bovine respiratory syncytial virus (BRSV) challenge.

Animals—Twelve 8- to 12-week-old calves.

Procedures—Calves received modified-live BRSV vaccine (vaccinated) or spent tissue culture medium (mock-vaccinated) intranasally, followed by challenge 30 days later with BRSV, or mock challenge with spent tissue culture medium (mock-challenge controls). Interleukin-4 (IL-4) and interferon-γ (IFN-γ) mRNA was measured in lungs, bronchoalveolar lavage (BAL) fluid cells, pharyngeal tonsils, and tracheobronchial lymph nodes, and tumor necrosis factor-α (TNF-α) mRNA was measured in lungs and BAL fluid cells by reverse transcriptase-competitive polymerase chain reaction assay.

Results—Resistance to clinical signs of disease was conferred in vaccinated calves. Expression of TNF-α mRNA in lungs and BAL fluid cells was higher in mock-vaccinated calves than control or vaccinated calves. In the lung, IL-4 mRNA expression was higher in vaccinated calves than control or mock-vaccinated calves. In pharyngeal tonsils, expression of mRNA for IL-4 and IFN-γ was higher in mock-vaccinated calves than control calves. In tracheobronchial lymph nodes, IFN-γ mRNA expression was higher in mock-vaccinated calves than vaccinated calves.

Conclusions and Clinical Relevance—Although vaccinated calves had decreased clinical signs of disease after BRSV challenge, compared with mock-vaccinated calves, this difference was not related to a T helper type 1 bias, as determined by increased expression of interferon-γ mRNA relative to interleukin-4 mRNA in lungs, BAL fluid cells, or tracheobronchial lymph nodes of vaccinated calves. Pulmonary inflammation was decreased in vaccinated calves as determined by decreased expression of TNF-α mRNA. (Am J Vet Res 2004;65:725–733)

Full access
in American Journal of Veterinary Research