Robert Siliciano, an AIDS researcher at the Johns Hopkins University School of Medicine, said on Monday at the XIV International AIDS Conference in Barcelona that HIV/AIDS will "never" be cured by antiretroviral medications because of latent HIV reservoirs in the body that avoid the impact of the drugs.

Siliciano explained during his address to the first plenary session that when CD4 cells are infected, most die, but many revert to a resting state, which provides a reservoir for future resurgence of infection. The present latent HIV reservoirs "makes the disease intrinsically incurable with antiretroviral therapy alone," even when blood-based viral levels are undetectable, he said.

"I think what we know now is that with antiretroviral drugs, although we can control the infection, we can never cure it." He did add that with improvements to existing anti-HIV medications and new drugs, it may be possible for HIV-positive people to have normal life expectancies despite the latent HIV reservoirs that may never be eliminated.

John Mellors of the University of Pittsburgh said during an IAS-WHO (International AIDS Society - World Health Organisation) satellite meeting on HIV drug resistance, which is one of the major topics of discussion at the conference: "Inexperienced physicians treating patients with HIV/AIDS pose a risk factor for the development of drug resistance."

He provided some key points which have been learned:

� No antiretroviral drug is resistance-proof. HIV has evolved to escape selective pressure whether it be from drugs or the immune system

� Incomplete suppression of HIV replication leads to drug resistance. This is often associated with incomplete adherence; multiple drug resistance is found in up to 30% of people on HAART after two years

� Resistance can lead to disease progression and death unless the viral RNA is suppressed to below 50 copies/mL

� Resistant viruses can spread, and can affect initial responses to therapy

� Resistance is not inevitable. Careful choice of regimens can minimise or prevent resistance

The WHO will set up a global drug resistance surveillance network to keep track of drug resistance worldwide. The programme will monitor outcomes to determine what causes or exacerbates, and what prevents drug resistance.