Bovine Myeloid Antimicrobial Peptide (BMAP) 28, a synthetic peptide derived from bovine cathelicidin-5 (amino acids 132-158), exhibits antimicrobial activity against E. coli, S. aureus, MRSA, S. epidermidis, and the fungus C. albicans, with minimum inhibitory concentrations (MICs) of 2, 2, 4, 1, and 8 µM respectively. At a concentration of 200 nM, BMAP 28 permeabilizes the inner membrane of E. coli, and at 5 µM, it inhibits herpes simplex virus 1 (HSV-1) replication in Vero 76 cells. Furthermore, at 30 µM, it causes hemolysis in human erythrocytes and cytotoxicity in human neutrophils. In vivo, a dose of 0.8 mg/kg enhances survival in mice infected with E. coli or MRSA, but not P. aeruginosa.