Possible vaccine for virus linked to type 1 diabetes

While an estimated 50,000 Swedes and 50, 000 Finns live with type 1 diabetes (sometimes known as juvenile diabetes) the causes of the disease remain unknown. There is a genetic component, but also environmental factors are needed for the disease to develop. One such factor believed to be significant in type 1 diabetes is infections caused by an extremely common group of enteroviruses. The sub-group in question is the Coxsackie B (CVB) family and it comprises of six strains that can give rise to the common cold. However, CVBs can also cause more serious infections leading to diseases including myocarditis and meningitis.

According to many scientific observations, one hypothesis suggests that CVBs play a part in the development of type 1 diabetes. The disease is characterised by an autoimmune attack on the insulin-producing beta cells in the pancreas and it is possible that the virus infection somehow initiates this attack by the immune system.

Epidemiological studies, in which children with a genetic risk profile for type 1 diabetes were monitored by blood tests over a period of many years, indicate that CVBs could be a pathogenic contributor. There are also autopsy observations suggesting that CVBs might be involved in the development of type 1 diabetes. This, however, remains hypothetical as the connection is yet to be proven, albeit it is a hypothesis that is well-established amongst diabetes researchers.

Vaccine protects against all six known strains of CVB

Researchers at Karolinska Institutet, Tampere University and University of Jyväskylä in Finland have now produced a vaccine that protects against all six known strains of CVB. The CVB serotypes to be used in the vaccine had been originally detected in the research performed in Vactech Oy in Tampere. The vaccine was tested in different animal models and was shown to protect mice infected with CVB from developing virus-induced type 1 diabetes.

The researchers then tested the vaccine in rhesus monkeys that have very similar genetics to humans. In these animals, the vaccine worked well and induced antibodies to CVB suggesting it could protect against the virus. An American pharmaceutical company is now going to perform clinical studies where they will test the vaccine in human subjects.

Assuming the vaccine is safe in initial trails, the plan is to use the vaccine in children with a genetic risk profile for type 1 diabetes. The researchers write that if the number of children that develop type 1 diabetes decreases after vaccination or if none develop the disease it will confirm that CVB are a triggering environmental factor.

"Our hope is that the vaccine will prove effective against CVB infections and that it will then be possible to administer it to children," says Malin Flodström-Tullberg, professor of type 1 diabetes at the Department of Medicine, Karolinska Institutet, Huddinge, and the study's corresponding author.

"It would be fantastic if the cases of type 1 diabetes that we currently suspect are caused by the Coxsackievirus could be prevented, though it's impossible right now to say what percentage of type 1 diabetes cases would be effected. At the same time, the vaccine would give protection against myocarditis, which can have a more severe course in both children and adults, and against many kinds of cold, which keep many people away from school and work."

"The research groups associated with this work have done fruitful collaboration already a longer time, to understand the infection mechanisms of enteroviruses and to develop vaccines and antivirals to combat enteroviruse infection," says Docent Varpu Marjomaki from the University of Jyvaskyla. Marjomaki is working also at Nanoscience Center at the University of Jyvaskyla.