Tiny gold particles coated with sugar molecules could be the perfect vehicle for delivering new vaccines that help humans build immunity against dangerous viruses. Pediatricians at Vanderbilt University used gold nanoparticles to build a possible vaccine for respiratory syncytial virus, one of the most prevalent infections observed in infants. Details of their vaccine candidate were published today in Nanotechnology.

Respiratory syncytial virus (RSV) is so common in babies, that it is assumed all newborns contract the disease before they are two years old. Most recover without any serious issues, but between 25 to 40 percent require hospitalization for pneumonia or bronchiolitis — inflammation of the lungs' smallest air passages, the bronchioles. In addition, adults who are immunocompromised and those over the age of 65 have an increased risk of severe consequences after RSV infection.

In order to prevent the 1 million worldwide deaths caused by RSV, a vaccine is needed. Gold nanoparticles are an attractive option because their tiny size mimics that of naturally occurring viruses.

"A vaccine for RSV, which is the major cause of viral pneumonia in children, is sorely needed," said lead author Dr. James Crowe.

The theory is that the gold nanoparticles can be coated with certain viral proteins that don't cause disease, but are recognized by cells in the human immune system. This could help people build immunity before contracting the virus.

"This platform could be used to develop experimental vaccines for virtually any virus, and in fact other larger microbes such as bacteria and fungi," remarked Crowe.

Crowe's team coated gold nanoparticles with viral material from respiratory syncytial virus, and then exposed these glittery carriers to human dendritic cells in a petri dish.

Dendritic cells are the immune system's sentinels. When the come across a dangerous germ, they capture it and then present it to more aggressive immune system members — B cells and T cells — that mount a serious attack agains the invader.

After being exposed to gold particles, the primed dendritic cells were transferred to a petri dish with T cells. The T cells became active and began multiplying, a sign that they were preparing an immune defense.

The researchers also found that the gold nanoparticles were non-toxic to these human cells.

"The studies we performed showed that the candidate vaccines stimulated human immune cells when they were interacted in the lab," concluded Crowe. "The next steps to testing would be to test whether or not the vaccines work in vivo [in animal models, humans.]"

Source: Stone JW, Thornburg NJ, Blum DL et al. Gold nanorod vaccine for respiratory syncytial virus. Nanotechnology. 2013.