13 September 2011
By , Pushpa Narayan
Inability To Mass Produce Vaccine Scuttles The Search For A Cure
Indian scientists have decided to stop the trials for a possible AIDS vaccine – which began in 2006 – though it proved to be safe in phase 1 and showed promise in fighting the virus. The scientists said they were unable to take the study further because mass production of the vaccine wasn’t possible.
Scientists say this is a setback to Indian efforts to develop an indigenous AIDS vaccine. Researchers will now have to look for fresh candidates. “We are back to where it all began,” said Dr Rajat Goyal, country head, International AIDS Vaccine Initiative.
The National Institute of Research in Tuberculosis in Chennai and National AIDS Research Institute (NARI) spearheaded the phase 1 trial of the MVA (Modified Vaccinia Anacara)- based vaccine candidate (TBC-M4). The effort was part of the International AIDS Vaccine Initiative. The vector-based vaccine
In 2007, the results showed that the vaccine was safe and tolerated by the body without side effects. But scientists felt they could increase the strength of the vaccine by giving a booster. This trial began in 2009 and on September 14, scientists told an international AIDS conference in Bangkok that the vaccine strength did not double as expected. “It is possible to scale up research. But we will not be able to do that because we are not able to mass produce this vaccine,” said Dr V D Ramanathan, who led the research from the Tuberculosis Centre.
In the MVA vaccine, six modified genes of the HIV are inserted inside a shell of weakened small pox vaccine. So far, the vaccine has been administered to 64 healthy individuals in two phases. For further studies, the scientists required at least 1,000 doses of the vaccine. Normally, in vaccine production, a source is created and multiplied. “The vaccine began to lose its strength as we tried to scale up production and increase the volume,” said Dr Goyal. But scientists hope that they might be successful in scaling up production in future.
Trials & Errors a Look at what the Experiments Around the World for an Aids Vaccine has Thrown up Trials that Gave Hope rv144
genes – was declared a qualified
success in 2009 after a 6-year trial.
It demonstrated that though the vaccine
lowered the number of people contracting
HIV infection, it had no effect on the amount of
virus in the blood of volunteers who got AIDS
through unsafe sex and drug abuse
| The AIDSVAX vaccine was developed in 1991 in California. The vaccine was based on gp120, a sugar-coated protein molecule found on HIV. The vaccine boosted production of antibodies (an infection-fighting protein molecule) in the blood. It knocked gp120 off the HIV and saved T cells (part of white blood cells that fight infection) from destruction. A revised version of the vaccine was produced in 1995 after a second strain of HIV was discovered. The trials were discontinued after phase II when some volunteers developed the infection even while taking the vaccine
| Study was funded by the National Institute of Allergy and Infectious diseases in the US. It tested an experimental vaccine called V520 to stimulate the body to produce T cells. In smaller trials, this vaccine was found to be safe on patients. But the trial was discontinued in 2007 after the vaccine upped the risk of HIV infection in some of the 3,000 volunteers
What is a vaccine?
It's a preparation that stimulates an immune response that can prevent or create resistance to an infection
How does it work?
In normal cases, an individual's immune system (in-built mechanism to fight disease) learns how to fight the disease only after the body is exposed to the infection once. But a
vaccine trains the immune cells in advance to recognise the invaders and beef up the internal security against future attacks
Why is HIV/AIDS vaccine complicated? At present, no effective AIDS vaccine is available. HIV is very good at evading and sabotaging the immune system, making it hard to understand how to create the best immune response with a vaccine. Developing any vaccine takes a very long time — polio vaccine took over 40 years
Can volunteers become infected by HIV during vaccine trials?
Trial vaccines cannot cause infection because they do not contain HIV. The vaccines contain only copies of small bits of genetic material from HIV, which means it cannot cause infection. The bits can be used on their own or inserted in a different virus, which is usually harmless to the human body. In the Chennai trial they used the small pox vaccine as the shell and inserted Indian strains of HIV into them
How far was the Chennai trial successful?
Results of the phase 1 showed that the vaccine was safe for volunteers. This means, scientists will be able to scale up research to see if the vaccine is effective in producing immunity. This will first be tested on hundreds of healthy individuals in phase II and then on those with HIV
The road block?
Scientists are unable to mass produce the vaccine for trials. When they tried to mass produce from a source vaccine, the efficacy came down drastically