Friday, July 27, 2007
Gaps in HIV/TB research spell 'catastrophe'
*A Guinean man, Conakry, who has both HIV and TB
Gaps in HIV/TB research spell 'catastrophe'
T. V. Padma
24 July 2007
[SYDNEY] Experts have warned of an impending catastrophe if critical gaps in the research and management of HIV/AIDS and tuberculosis are not urgently closed.
Tuberculosis (TB) kills about two million people every year, and is the leading cause of death in people with AIDS.
Today (24 July), at an international conference on HIV in Sydney, Australia, experts said poor countries are bearing the brunt of the twin epidemics.
TB cases have been rising in sub-Saharan Africa since 1990, said Stephen Lawn, a researcher from the University of Cape Town, South Africa.
The areas worst hit by both infections are southern and eastern Africa, he said, where half of all people newly diagnosed with TB already have HIV.
Lawn says studies in Botswana show the current WHO-approved TB treatment strategy called DOTS (Direct Observation and Treatment – Short Course) has not reduced TB in HIV-infected people. "DOTS alone does not work," he said.
And both epidemics are being made worse by the emergence of extremely drug-resistant TB. Gerard Friedland, director of the AIDS Care Programme at Yale University, said that in areas with high rates of TB and HIV infection, drug-resistant TB threatens the success of both the World Health Organization's (WHO) Stop TB initiative, and HIV programmes rolling out antiretroviral drugs.
Speakers at the sessions highlighted areas critically in need of research, including measuring more accurately the burden and impact of TB in HIV-infected people.
A 2006 survey by the WHO found that most countries facing an HIV epidemic are not reporting the increase in TB cases, and that HIV-infected people are not benefiting from access to TB screening and subsequent treatment services.
Research into finding new diagnostic, screening and intervention tools is also needed. Doctors in most parts of the world are using a diagnostic test that is over a century old, and whose sensitivity in patients with both TB and HIV infections is just 20 per cent. This is "wholly inadequate", says Lawn.
Research is also needed to find out what anti-HIV treatment regime is most suitable for people infected with TB. Likewise, information on how best to treat TB infection in people with HIV is lacking.
Trials underway for 'essential' new TB vaccine
Contact: Craig Brierley
Clinical trials are underway with the first new vaccine against TB in over 80 years. If successful, the tests will have major implications for TB control and could lead to the development of a new vaccine ready to use within eight years.
The need to control TB has become more urgent with the resurgence of the disease in many parts of the world, including a 10% rise in England, Wales and Northern Ireland, and the emergence of multi-drug resistant strains.
TB, which is caused by the M. tuberculosis bacterium, is thought to kill two million people every year. The UK's Health Protection Agency recorded over 8,000 cases in 2005, including almost 3,500 in London alone.
The vaccine has been developed by Dr Helen McShane, a Wellcome Trust Senior Clinical Research Fellow, working with Professor Adrian Hill, a Wellcome Trust Principal Research Fellow, both at the University of Oxford. Dr McShane has been awarded a Strategic Translational Award from Technology Transfer at the Wellcome Trust to develop and test the vaccine, which currently leads the field. Additional funding has been provided by the European Commission.
Currently, the only vaccine against it is the BCG vaccine, which is administered to infants throughout the developing world and most of the developed world. However, the vaccination is only thought to be protective in preventing severe forms of the disease and is not effective in adults. In addition, antibiotics to deal with infection must be administered over many months and are becoming increasingly ineffective as the bacteria develop resistance to the drugs available.
"In children, the current vaccine provides some protection against severe forms of the disease, but there is clearly room for improvement," explains Dr McShane. "The rise in the number of cases of multi-drug resistant forms of TB plus the increasing number of cases of TB in people living with HIV means a new vaccine is essential. We can no longer rely on antibiotics to treat the disease– we need to help the body's immune system prevent disease."
The vaccine currently under development by Dr McShane, known as MVA85A, works in tandem to the BCG, acting as a booster. It uses the 85A antigen, a protein found in all strains of TB, to boost the response of T cells already primed by the BCG vaccine. T cells are produced by the body's immune system to fight infection. This vaccine uses a virus as a delivery system for the protein and the results of the clinical trials to date show the highest T cell responses ever induced with a vaccine.
"This vaccine is safe and stimulates very high levels of the type of immune response we think we need to protect against TB. It is important for us to test whether or not this vaccine does work to stop people getting TB," says Dr McShane.
Following successful safety trials in The Gambia, the drug has now entered phase II trials in The Western Cape in South Africa, where the incidence of TB disease in infants is 1 in 100 (despite BCG vaccination). It has first been tested in HIV negative adult volunteers and these trials are now being stepped down into adolescents, and also into HIV infected adults. Once Dr McShane and her team are fully confident of the safety of the vaccine, and the strength of the immune response induced by the vaccine, it will be given to infants to test its efficacy. This is important as one of the target populations for a new TB vaccine is infants.
"The aim of our award is to enable Helen to demonstrate efficacy of the vaccine in a relevant population," says Dr Ted Bianco, Director of Technology Transfer at the Wellcome Trust, which is funding the trials. "There is a clear need for a new TB vaccine and so this work will have very significant healthcare implications both for the developed and developing worlds."
Commenting on the trials, Paul Sommerfeld, Chair of TB Alert, said:
"It is immensely important that a new, and potentially much more effective, vaccine against TB is going into second stage trials. The TB bacterium has for too long managed to stay a step ahead of human efforts as shown by the appearance, especially in HIV positive populations in Southern Africa, of a strain of tuberculosis resistant to virtually all known drugs against TB. To have a new tool for preventing TB would be a great step forward."
Posted by lmurx at 5:51 PM