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Challenges of HIV-1 subtype diversity

Genetic variation of HIV-1 explored

Henry M. Jackson Foundation for the Advancement of Military Medicine

A review article in the New England Journal of Medicine explores the genetic variation of HIV-1 and its implications for preventing and treating the disease. Francine McCutchan, Ph.D., a researcher with the U.S. Military HIV Research Program, co-authored the article, which appeared in the April 10, 2008 edition.

HIV-1 is classified into several subtypes, or clades, which are denoted by letters. Subtype B is most prevalent in the Americas, whereas clades A, C and D are most prevalent in Sub-Saharan Africa, the region that remains most severely affected by the pandemic.

Advances in full-genome sequencing, along with expanded disease surveillance, have enabled researchers to identify circulating and recombinant forms of the disease as well.

"Given the diversity of HIV-1, gathering and classifying its strains has been very challenging. Nevertheless, this data provides the foundation for understanding the virus, its spread and how to combat it," said Dr. McCutchan.

The authors address the implications viral diversity has on HIV prevention, vaccine development and antiretroviral therapy. For example, subtypes and their interaction with the human host may influence disease progression and transmission. They cite a cohort study in the Rakai district in Uganda, which suggested that HIV-1 disease progression is more rapid, and the risk of death is greater, among persons infected with subtype D (with recombinant forms or multiple subtypes) than those infected with subtype A.


USMHRP, centered at the Division of Retrovirology, Walter Reed Army Institute of Research (WRAIR), and conducted in collaboration with the Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) . The program's success is achieved through collaboration among U.S. and international agencies, host country militaries and governments, universities and community organizations, along with a network of overseas DoD research laboratories. USMHRP has develop a robust international infrastructure, especially in sub-Saharan Africa and South/South-East Asia.

While its primary focus has been on developing a globally effective preventive HIV-1 vaccine, the program is actively committed to and engaged in providing effective prevention, care and treatment programs in each of the communities in which they conduct research. At these sites, they also focus on strain surveillance, cohort development, therapeutic studies, and study the social behaviors that influence HIV infection.

The program's threat assessment and global molecular epidemiology activities are aimed at tracking the HIV epidemic in active duty forces and assessing the risk of HIV exposure to U.S. and allied forces deployed overseas. For more information, please visit their website or contact

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