May 30, 2011

 

Australian vaccine to protect against Bovine Viral Diarrhoea Virus
 
 
A new nanovaccine could help cows fight against the destructive Bovine Viral Diarrhoea Virus (BVDV), protecting the Australian livestock sector from losses of millions of dollars annually, according to Australian scientists.

 

The new BVDV nanovaccine, which is a protein from the virus that has been loaded onto nanoparticles to act as the delivery vehicles, has been shown to produce an immune response in trials against the industry's most destructive virus. The researchers hope to explore the potential of developing a nanoparticle-based delivery technique for veterinary and human vaccines.

 

"Our research has demonstrated that the BVDV nanovaccine has the potential to offer better protection against this cattle virus, can be stored at room temperature and has a long shelf life," said researcher Neena Mitter, of the Queensland Alliance for Agriculture and Food Innovation (QAAFI) at the University of Queensland (UQ).

 

"This research paves the way for the team to develop a platform technology for similar nanovaccines for other animal and human diseases in the future."

 

BVDV, also known as Bovine Pestivirus, is a viral infection of cattle that appears in feedlots, and beef and dairy herds in Australia. First diagnosed in the US, the disease has existed in Australia for over 40 years, and the current vaccine is restrictive in its delivery methods, short shelf-life, and required frequency of shots.

 

BVDV is highly contagious because it takes as little as one hour of direct contact between an infected animal and an uninfected animal for the disease to be transmitted; thus, causing respiratory infections, infertility, abortion and diarrhoea.

 

According to QAAFI co-researcher Tim Mahony, BVDV threatens the long-term profitability of cattle industries across Australia as cattle producers can experience productivity losses of between 25% and 50% following discovery of BVDV in previously uninfected herds.

 

"In Queensland alone, the beef cattle industry is worth approximately AUD3.5 billion (US$3.7 billion) per year and the high-value feedlot sector experiences losses of over AUD60 million (US$64.2 million) annually due to BVDV-associated illness," he said.

 

In the study, the multidisciplinary team including nanotechnology experts Max Lu and Shizang Qiao from UQ's Australian Institute for Bioengineering and Nanotechnology, loaded the BVDV protein onto silica nanoparticles around 100 nanometres wide and injected that into mice. The mice appear to have remained healthy.

 

The team found that the nanoparticles did not require any adjuvant, a substance included in vaccines to boost immune responses, to be added. Currently, adjuvants are added to most conventional vaccines to improve vaccine-induced protection from diseases.

 

"The cost of formulating vaccines with adjuvants can significantly contribute to the price of vaccines. Nanoparticles offer the potential of reducing the cost of vaccines as they do not require the addition of adjuvants," said Mahony. "Also, vaccines are administered just once or twice in a lifetime, as opposed to drugs that require a more regular intake."

 

"Nanoparticle-based vaccines have been around for some time but it all depends on the technology that this group has used and how it differs from previous studies," said Jean-Pierre Scheerlinck, director at the Centre for Animal Biotechnology at the University of Melbourne, whose team had investigated the potential use of nano-bead vaccines in 2006.

 

Referring to the size of the silica nanoparticles used in this study (100 nanometres), he pointed out, "Groups of researchers have focused on different sizes and found quite different properties."

 

Angus Johnston, research fellow at the Department of Chemical & Biomolecular Engineering at the University of Melbourne said that there is a significant potential for nanovaccines to improve vaccination outcomes, and also noted that the size range of nanoparticles that is receiving the most attention in recent research is between 50-200 nanometres.

 

"This size range is good because it can readily enter cells where it needs to deliver the therapeutic cargo, and tends to have better biodistribution than larger particle sizes, meaning it will have a longer circulation time in the blood."

 

Using its successful BVDV nanovaccine as a model system, the team now plans to develop similar nanotechnology-based vaccines for other animal and human diseases.