Recent advances in rhinovirus therapeutics.

Human rhinoviruses are the major causative agents of the common cold. Because there are greater than 100 viral serotypes, little immunological protection is afforded to humans by prior rhinovirus exposure, which accounts for the high incidence of infection. In most cases, rhinovirus leads to a short self-limiting illness. However, for asthmatics, the elderly and immunocompromised patients, rhinovirus infection can lead to life-threatening complications. This has spurred a consistent effort over recent decades to identify effective treatments and preventions for rhinovirus infection. While some work has focused on alleviating the symptoms induced as a result of inflammatory pathways stimulated by rhinoviruses, the majority of the research has been focused on limiting or preventing viral infection altogether. Various approaches have been taken to halt rhinovirus infection. Prevention of virus-cell interaction has been the aim of research on viral capsid binders and cell receptor blockers. Interference with correct viral protein processing is the goal of the design and testing of protease inhibitors. Current work is attempting to interfere with viral RNA replication by testing silencing RNA molecules. In this review, we will discuss recent advances in the development and testing of human rhinovirus therapeutics.

Humanization of an anti-ICAM-1 antibody with over 50-fold affinity and functional improvement.

The monoclonal antibody 1A6 binds to human intercellular adhesion molecule 1 (ICAM-1, CD54) and inhibits infection by 90% of human rhinovirus (HRV) serotypes. To make a therapeutic molecule for preventing and treating HRV infection, we humanized a single chain antibody (scFv), 1A6, by a structure-guided complementarity-determining region (CDR) grafting procedure. Our final humanized 1A6 scFv does not retain any mouse back mutations in the framework. Without changing the CDR sequences, the humanized 1A6 scFv demonstrates over 50-fold improvement in both affinity for ICAM-1 and protection efficacy against HRV infection in vitro.

Prevention of human rhinovirus infection by multivalent fab molecules directed against ICAM-1.

We have developed a technology for improving avidity by making bivalent, trivalent, or tetravalent recombinant polypeptides. We designed tripartite proteins consisting of the Fab fragment of an antibody fused with a hinge derived from human immunoglobulin D that was further linked to polymerization domains derived from human coiled-coil proteins. We report here on the application of this method with a Fab domain directed against the major human rhinovirus receptor, intercellular adhesion molecule 1 (ICAM-1). Multivalent anti-ICAM-1 molecules were produced in bacteria and purified as soluble preassembled homogeneous proteins at high yield. These proteins successfully blocked rhinovirus infection in vitro, with the efficiency increasing from monomer to dimer, trimer, and tetramer. The diminished dissociation rate of these multivalent antibodies and their improved efficacy in preventing rhinovirus infection provide a foundation for producing prophylactic and therapeutic molecules against human rhinovirus, the causative agent of the majority of common colds.