Human rhinoviruses (HRV) are tiny, highly variable viruses that are one of the main causes of the common cold.   Stephen Liggett’s group has analyzed all 99 human rhinovirus genomes in the ATCC and come up with all kinds of fascinating insights. 1

How diverse are HRV? What maintains diversity or  lack of diversity?

The lack of broader diversity suggests all HRVs are in a stable status for maintaining selection for certain traits, yet still have mutational flexibility for escape from immune responses.

Have we found most of the HRV out there?

… the sequence space occupied by the available samples suggest that there may be many additional HRV-C strains awaiting discovery. Distance extrapolations relative to the new full reference cohort, predict the HRV-C may have an even broader range of serotypes than the original 99, of which each confers only limited immunologic cross-protection to another.

Where do new HRV come from?

Co-infection with multiple HRVs is known to occur, and we now know this can lead to unique strains that may have distinct biologic properties and clinical characteristics.

Here’s the big picture (click for a larger version).

Liggett human rhinoviruses

Update: Vincent Racaniello of This Week in Virology and The Virology Blog notes in the comments that the ATCC sequences this paper relies on understate rhinovirus diversity, at least partly because an unknown number of rhinoviruses can’t be cultured for classical identification, and points out a paper from last year2 that identified other pathogenic human rhinovirus by a sequencing approach.

  1. Palmenberg, A., Spiro, D., Kuzmickas, R., Wang, S., Djikeng, A., Rathe, J., Fraser-Liggett, C., & Liggett, S. (2009). Sequencing and Analyses of All Known Human Rhinovirus Genomes Reveals Structure and Evolution Science DOI: 10.1126/science.1165557 []
  2. DOMINGUEZ, S., BRIESE, T., PALACIOS, G., HUI, J., VILLARI, J., KAPOOR, V., TOKARZ, R., GLODE, M., ANDERSON, M., & ROBINSON, C. (2008). Multiplex MassTag-PCR for respiratory pathogens in pediatric nasopharyngeal washes negative by conventional diagnostic testing shows a high prevalence of viruses belonging to a newly recognized rhinovirus clade Journal of Clinical Virology, 43 (2), 219-222 DOI: 10.1016/j.jcv.2008.06.007[]