SciDev.Net

In this editorial* (J Infect Dis 189:2149-53, 15 June 2004), Marc Butlerys and his co-authors review the success and progress of strategies aimed at the prevention of MTCT during breastfeeding, and outlines the challenges for future research. These include the refinement of antiretroviral drug regimens, and the use of (still experimental) alternatives such as antibodies to clear any HIV that crosses to the baby during breastfeeding.  

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In this commentary article, timed to precede the international microbicides conference held in London in March 2004, researchers Robin Shattock (United Kingdom) and Suniti Solomon (India) provide a brief overview of the scientific strategies being used in microbicides research and development.

Written for general readers with a scientific or medical background, the article contains some technical terms but also has a useful graphical illustration showing the targets of microbicide action. These include directly killing or immobilising HIV, and preventing cells that line the female genital tract from transporting the virus to deeper tissues in the body.

In this commentary article, HIV vaccine researcher Ron Desrosiers presents his view that the main reason we do not yet have a vaccine for HIV is due to unsolved scientific questions rather than a bottleneck in conducting clinical trials. Accordingly, he advocates a "renewed, coordinated and focused effort" on basic research rather than clinical trials for "feeble" candidates that "stand little chance of being effective".

Desrosiers is well known and respected in the HIV research field for his contribution to the scientific debate, and presents five lines of evidence for his contentions. These include the failure of immune responses elicited by current vaccines in HIV-infected individuals to control the virus; the failure of the animal models much favoured by researchers to fully represent HIV infection in humans; and the ability of new strains of HIV to 'super-infect' individuals already infected with another strain, even if their immune system appears to be controlling the first infection. He also disagrees with the aim of the recently formed "Global Vaccine Research Enterprise" of placing more candidates in clinical trials more quickly. 

The article is written for general readers with a scientific background, and assumes knowledge of how the immune system works and relevant technical terms. Nonetheless, it is a well-argued piece that provides much food for thought for the vaccine community and policymakers alike.

This optimistic review, by Marc Bulterys and colleagues at the US Centers for Disease Control and Prevention, summarises recent advances in preventing mother to child transmission (MTCT) of HIV-1. Without any intervention, the risk of MTCT is 15 to 40 per cent, amounting to 1,700 new paediatric infections a day.

In the West, interventions combining elective caesarean section and antiretroviral drugs have reduced this risk to around one per cent. However, such measures require a well-established infrastructure and healthcare system that is expensive and lacking in most of the developing world. The authors state that it is therefore necessary to explore the potential of simpler, less expensive treatment options.

The article includes a detailed account of individual clinical trials on the use of antiretroviral drugs to prevent MTCT, as well as pilot programmes to expand prevention of MTCT in developing countries. It also contains useful tables summarising the current knowledge of factors affecting MTCT, a list of completed phase II/III clinical trials of antiretrovirals (up to February 2002), and outlines a model for implementing a programme preventing MTCT in developing countries.

The authors of this scientific article use a mathematical model to warn that while the widespread use of antiretrovirals in developing countries could be an effective tool for prevention of HIV infection - as well as treatment - the benefits could be masked by an increase in risky behaviour that promotes the spread of the virus.

They argue that antiretrovirals should be viewed as a non-conventional prevention tool since the drugs have both preventive and therapeutic effects and are given to infected, rather than uninfected, individuals.

In this article, leading vaccine researchers and advocates join forces to call for a global strategy for developing an effective HIV vaccine. The goal, they say, would be to unite teams of researchers in a series of coordinated global HIV vaccine centres, each with the critical mass, focus and scientific expertise for a more rapid and systematic approach to vaccine development.

The authors point to the recent success of the Human Genome Project in achieving the full sequencing of the human genome within a shorter than predicted timeframe. They say this provides an encouraging model, which highlights the need for a common vision among funders and major stakeholders, including those from developing countries.

Written by a virologist for a clinical readership - but likely to have broader appeal - this article describes in some technical detail the challenge that the unique biology of HIV infection poses to vaccine development. It provides an expert view of the strengths and weaknesses of current vaccine designs, the kind of immunity they trigger, and safety issues.

Letvin argues, with reference to animal studies, that a vaccine may still be worthwhile even if it fails to completely eliminate HIV from the body (known as 'sterilising immunity'), on the grounds that it would enable people to control their virus infection sufficiently to live longer and healthier lives, as well as lower the chance of the virus spreading to others.