A sophisticated scanning technique can track the progression of HIV and could lead to new treatment options and the development of the next generation of anti-HIV drugs, scientists said on Friday. Positron emission tomography scans are usually used to identify cancerous tumors, but researchers believe the technology could play an important role in the battle against AIDS by identifying the impact of the virus on lymph nodes that could be treated with radiotherapy or surgery. The lymph nodes are believed to be major HIV reservoirs that can evade the effects of anti-HIV medications.
C. David Pauza and scientists at the University of Maryland Biotechnology Institute in Baltimore took whole-body PET scans of 15 HIV patients and found fairly distinct sites of immune response during different stages of the illness. "We believe that if we identify those sites clearly during HIV infection, we encourage people to consider these types of interventions," Pauza said, referring to surgery or radiotherapy. During early disease, lymph nodes in the head and neck were activated, according to the PET scans, but in later stages the virus stimulated an immune response in areas of the torso and later in the bowel.
HIV disease is currently treatable only with antiretroviral drugs. Surgery or radiotherapy would open up a new approach to the illness that has affected 42 million people worldwide. "We are not aware that it has ever been tried," said Pauza, who reported his findings in The Lancet. "We think it is appropriate to consider these approaches and also appropriate to learn from the cancer models because cancer is a disease of chronic cell activation and growth, and in some ways--even though HIV is triggered by a virus--it has some similarities."
In cancer patients, PET scans measure the activity of cancerous cells, while in HIV it picks up levels of immune system reaction. David Schwartz and Sujatha Iyengar, of the Johns Hopkins University Bloomberg School of Hygiene and Public Health who also used PET scans to track HIV progression, said lymph node removal could give patients an opportunity for a break in antiretroviral treatment. "Although many systemic sites from which latent virus could be reactivated would be left, reactivation might not occur for months or years after removal of the active nodes, thereby allowing extended interruption of treatment," Schwartz wrote in a separate study published in The Lancet.
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