Described herein are peptides having antimicrobial activity (antimicrobial peptides). The antimicrobial peptides, designated LBU, WLBU and WR, are analogs of the Lentivirus Lytic Peptide 1 (LLP1) amino acid sequence. The antimicrobial peptides are monomers or multimers of peptides referred to as the Lytic Base Unit (LBU) peptides, derived from the LLP1 analogs and also having antimicrobial activity. Also described herein are using the peptides in a variety of contexts, including the treatment or prevention of infectious diseases. Methods of killing fungi, such as Candida and Cryptococcus species, and bacteria, such as B. anthracis, are provided herein. Methods of neutralizing enveloped viruses, such as poxvirus, herpesvirus, rhabdovirus, hepadnavirus, baculovirus, orthomyxovirus, paramyxovirus, retrovirus, togavirus, bunyavirus and flavivirus, including influenza virus and HIV-1 also are provided herein. Solid phase substrates and peptide-cargo complexes comprising the peptides also are provided.