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New inhaling TB vaccine successfully vetted

25 Mar 2008

Joao Souza

Source: Eurekalert (see original article)

Figure 1
Mycobacterium tuberculosis

A needle-free, dry-powdered, inhaled TB vaccine, administered as an oral mist has been tested on guinea pigs with encouraging results, as reported in the Proceedings of the National Academy of Sciences. The vaccine used in the tests was BCG (Bacillus Calmette-Guérin) – the world’s most administered childhood vaccine.

The study was conducted by researchers at the University of North Carolina, Chapel Hill; the Aeras Global TB Vaccine Foundation; the international not-for-profit Medicine in Need, South Africa; and the Harvard School of Public Health and School of Engineering and Applied Sciences. The research was supported by a Grand Challenges Grant from the Bill and Melinda Gates Foundation.

According to the PNAS paper, prior ‘published studies on inhaled vaccines for TB have mostly involved nebulized solutions, a process that necessitates large volumes of water with long administration times … dried forms of vaccines, as formed traditionally by freeze drying and recently by spray drying, present an alternative to nebulization but pose risks to the integrity of dried bacteria and produce powders with suboptimal dispersive characteristics.’

The researchers now say that, ‘by designing bacterial vaccines via rapid drying we can exploit the natural tendency of dried bacteria to assume elongated shapes and achieve remarkably effective airborne properties’.

‘It is at least as good as the injectable vaccine’, said Anthony Hickey of the Molecular Pharmaceutics Division, University of North Carolina, Chapel Hill, in a press statement. ‘The real advantage is that this vaccine does not need to be refrigerated. It also does not require needles, syringes and water like the injectable vaccine and administering it is as easy as breathing in, making it ideal for use in developing countries.’

‘Tuberculosis is one of the most resistant and challenging diseases to protect against, and the successful results of aerosol delivery using nanoparticle technology potentially offers a new platform for immunization’, said Barry Bloom, Dean of the Harvard School of Public Health, adding: ‘Were the animal results here confirmed in human studies, this technology could be used not only for TB vaccines, but those protecting against other infectious diseases as well.’

The new hopes brought by the PNAS paper comes at a time when a new WHO report, Global tuberculosis control 2008, says the pace of the progress to control the TB epidemic slowed slightly in 2006, the most recent year for which data were available.

Pathogenic bacteria considered to be potential targets for the inhaledvaccine include: Mycobacterium leprae (leprosy); Yerasinia pestis (plague) and Bordetella pertussis (whooping cough). According to the PNAS paper, the principles and preparations used for bacterial vaccine delivery might also be effective in delivery of other live vaccines, including those for viral diseases.

Reference

1. Garcia-Contreras L, Wong YL, Muttil P et al (2008). Proc Natl Acad Sci. Immunization by a bacterial aerosol [Abstract only: Epub ahead of print].

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