This invention pertains to biocatalysts that are specifically targeted to bind pathogens, such as viruses, and to degrade components of pathogens in order to abrogate their pathogenicity, and to methods of preventing or treating infection by pathogenic organisms. The biocatalysts comprise a binding agent which specifically binds a surface component of a pathogen, for instance the gp120 viral coat protein of the Human Immunodeficiency Virus, and a catalytic moiety which degrades a component of the pathogen so that its pathogenicity is abrogated. The binding agent and the catalytic moiety are linked by chemical linkers or genetic engineering techniques.