Commonly implicated agents include rhinoviruses, coronaviruses, influenza virus, respiratory syncytial virus (RSV), adenovirus, and parainfluenza. At least 99 serotypes of human rhinoviruses affecting humans have been sequenced. Those most affected by rhinoviruses are infants, the elderly, and immunocompromised people. On the other hand, rhinoviruses infect primarily the nose and the throat. Human rhinoviruses (HRVs) contain four structural proteins labeled VP1-VP4. Picornain 3C is encoded by enteroviruses, rhinoviruses, aphtoviruses and cardioviruses. Rhinoviruses belong to the genus Enterovirus in the family Picornaviridae. Rhinoviruses are known to be the most important common cold viruses. Rhinoviruses are spread worldwide and are the primary cause of the common cold. Rhinoviruses have single-stranded positive sense RNA genomes of between 7200 and 8500 nt in length.