Rhinovirus diversity and virulence factors

The rhinovirus (RV) genus is highly diverse, consisting of three species and more than 167 subtypes, utilizing three different receptors for cell entry. This diversity has been an obstacle to the development of effective cross-reactive antiviral treatments or vaccine strategies. Accumulating research suggests a possible association of virus species/subtypes with illness severity presenting the possibility for antiviral approaches targeting specific subtypes instead of all RVs. To facilitate such an approach, identification of the underlying molecular mechanism and the viral factor/s that mediate disease is required. Recent literature shows a clear species/subtype associated divergence in the host cell directed activity of RV proteases. Whether these differences correlate with the subtype-specific differences in illness severity remains to be confirmed. In this chapter, we bring together current knowledge of the association of RV species/subtypes with illness and explore the possible role of RV proteases as the main virulence factors associated with illness severity.