A vaccine for AIDS is still years away, warns a new report, with progress being hampered by a lack of scientific, political and economic interest.
Only one vaccine candidate has been tested fully to see if it can work in humans, says Seth Berkley, president and CEO of the International AIDS Vaccine Initiative (IAVI), which released its progress report on Monday. 鈥淭hat is a global disgrace,鈥� he says. 鈥淭here hasn鈥檛 been a serious effort.鈥�
Data on so-called cell-mediated vaccines 鈥� which invoke the response of the body鈥檚 T-cell system 鈥� will be available by 2010. Providing the data are positive, this is the earliest point at which an AIDS vaccine will be close to becoming a reality, Berkley says.
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鈥淭he world is inching toward a vaccine, when we should be making strides,鈥� Berkley said during the launch of the report at the XV International AIDS conference in Bangkok, Thailand. 鈥淭he single biggest obstacle is that vaccine development is that it is not a top scientific, political and economic priority.鈥�
He adds that less than one per cent of global spending on health product research and less than three per cent of all money devoted to AIDS goes towards developing a vaccine for the disease.
Pipeline expansion
However, Berkely admits the 2004 report paints 鈥渁 more encouraging picture鈥� than previous IAVI progress reports, which are compiled every two years.
鈥淲e have seen a tremendous expansion of the pipeline [of vaccine candidates],鈥� adds Wayne Koff, senior vice-president and head of vaccine research at IAVI. He says the number of vaccine candidates is three times what it was at the time of the last International AIDS conference in Barcelona, Spain, in 2002. There are over 30 vaccine candidates currently being researched by drugs companies.
For instance, VaxGen鈥檚 gp120 product, AIDSVAC, has been through all testing stages. And a combination approach using Alvac to prime the immune system and VaxGen鈥檚 AIDSVAC is to be trialled in Thailand, with data expected in 2007 or 2008. Merck is also carrying out a phase IIB 鈥減roof of concept鈥� trial on a product based on adenovirus.
Antibodies and mucus
But a major concern is that all the vaccine candidates being investigated use the same approach to give immunity to HIV. 鈥淎ll of these elicit cell-mediated immunity,鈥� Koff told New 杏吧原创, recruiting the body鈥檚 T-cells to fight off HIV infection.
These vaccines are either DNA vaccines or use a vector approach. With the latter, a relatively harmless virus, such as canarypox, can be used to ferry in a few HIV genes, which then invoke an immune response.
Koff says other ways of developing a vaccine include invoking the antibody system or the mucosal immunity 鈥� resistance to infections across mucus membranes.
Live, attenuated vaccines have been successful in monkeys. 鈥淚ssues of reversion to the wild type virus have basically taken that off the table at this point,鈥� he says. 鈥淗owever, it is critical to try and identify why the concept of a live vaccine works in the SIV model as well as it has.鈥�
