As common as the common cold is, scientists have so far been unable to develop a viable vaccine against it, largely due to the fact that there are over 100 strains of rhinoviruses, the most common cause of the infection. Now, a team at Emory University has used a surprisingly simple technique, mixing multiple types of rhinovirus into one vaccine, and found it stimulated the immune system against all of the included types.

Vaccinating against individual serotypes of rhinovirus is possible, but not very effective since there's very little cross-protection between strains. To combat this, the Emory team simply combined dozens of different serotypes of inactivated rhinovirus into one mixture, and tested the treatment on mice and macaques.

The mice were vaccinated with 25 types, and the macaques with 50. In both cases, the treatment stimulated neutralizing antibodies in the animals' immune systems against all types in each mixture.

"It's surprising that nobody tried such a simple solution over the last 50 years," says Martin Moore, one of the researchers. "We just took 50 types of rhinovirus and mixed them together into our vaccine, and made sure we had enough of each one. If we make a vaccine with 50 or 100 variants, it's the same amount of total protein in a single dose of vaccine. The variants are like a bunch of slightly different Christmas ornaments, not really like 50 totally different vaccines mixed."

The antibodies released by the animals in response to the virus were tested on cultured human cells for their effectiveness in preventing infection, but not for their ability to prevent sickness in animals. Clinical trials on humans are on the way, to help determine if the discovery could lead to a viable vaccine.

"There are no good animal models of rhinovirus replication," says Moore. "The next step would be human challenge models with volunteers, which are feasible because the virus is not very pathogenic."

The research was published in the journal Nature Communications.