Host proteins

The term "Host proteins" refers to the entire complement of proteins produced by a host organism, such as a human, rather than a single specific therapeutic target (1.1.1). In the context of drug discovery, it is most frequently used to describe "host factors" that are hijacked by pathogens (e.g., viruses, bacteria) to facilitate their life cycle, leading to the development of host-directed therapies (HDTs) (1.1.2, 1.2.3). By targeting these stable host proteins instead of highly mutable viral proteins, researchers aim to create broad-spectrum antivirals with a higher barrier to resistance (1.1.4, 1.4.4). Examples of host proteins targeted by approved or investigational drugs include the CCR5 receptor for HIV treatment and the TMPRSS2 protease for COVID-19 (1.2.1, 1.4.1). Additionally, in the field of biologics manufacturing, "host cell proteins" (HCPs) refer to endogenous protein impurities from the production cell line (e.g., CHO cells) that must be rigorously removed from the final drug product to prevent adverse immune reactions in patients (1.4.2, 1.4.5). Because the term encompasses thousands of distinct molecules with diverse functions, it is considered a broad category rather than a specific, actionable drug target (1.3.2).

Other names

Host factorsCellular factorsHost cell proteinsHCPsHost dependency factors

Inhibition of host factors essential for pathogen life cycles; modulation of host immune responses; removal of protein impurities in drug manufacturing.