Abstract: The present application relates to compositions for preventing or treating viral and other microbial infections. In some embodiments, the present application provides chimeric proteins comprising a target-binding moiety that specifically binds to a pathogen that infects through a mucosa, and a positively charged mucoadhesive peptide fragment. Also provided are antibodies and constructs thereof that specifically binds to an S1 subunit of a spike protein of SARS-CoV-2. Compositions comprising the chimeric proteins, antibodies, or constructs described herein are useful for preventing or treating a microbial infection in an individual, such as a coronavirus infection.