The Evolution of HIV (review)

The Evolution of HIV. Edited by Keith Crandell. Baltimore: Johns Hopkins Univ. Press, 1999. Pp. 504. $75 (hardcover), $35 (paper).

We are in the midst of an expanding infectious disease disaster, and at its source is a virus, HIV-1, first identified only 15 years ago. Though we can anticipate that the HIV/AIDS epidemic will continue to worsen for the foreseeable future, the scientific effort to understand the biology of HIV-1 and combat this scourge has been unprecedented in the history of infectious disease research. One remarkable property of HIV-1 is its propensity to mutate rapidly during reverse transcription. This feature is amplified by the high replication rate of HIV-1, its high population density in infected tissues, and its persistence over many years in a single host. This results in genetic heterogeneity among viral isolates from a single individual (so-called "quasispecies"), the potential for escape from antiviral immune responses, and the development of resistance to antiretroviral agents when viral replication is incompletely suppressed.

The Evolution of HIV attempts to integrate current knowledge of the molecular biology of HIV-1 and molecular evolutionary theory in an effort to highlight the power of HIV-1 as a system for studying molecular evolution. As described in this book, the longitudinal study of sequence diversity of HIV-1 in a single individual over a two-year period is the molecular evolutionist's equivalent of studying typical gene regions for two million years of evolution sampled every 100,000 years. The book effectively portrays the potential for HIV-1 as a system for studying phylogenetic methods. Like most books published about HIV, parts of the book are already out-of-date. Nonetheless, the reviews of HIV-1 molecular biology and phylogeny are well written, and the perspective feels very fresh because the authors focus on evolutionary aspects of HIV-1 and introduce evolutionary biology concepts and methods.

The book is organized into three sections. The first, "Introduction to HIV," reviews the molecular biology and global phylogenetic diversity of HIV-1. This section provides a concise and readable review and is accessible to most readers. The second section, "Molecular Methods for Studying HIV Diversity," examines advanced evolutionary biology methods in the context of HIV-1 evolution, including phylogenetic methods, modeling the molecular evolution of HIV sequences, the use of phylogenetic inference to test an HIV transmission hypothesis, and coalescent approaches to HIV population genetics. This section would be of most interest to evolutionary biology students and researchers and to HIV molecular biologists with an interest in advanced phylogenetic analysis methods. Readers with a more general interest in HIV biology and phylogeny might be a bit overwhelmed. The third section, "Case Studies of HIV Evolution," examines levels of diversity of HIV-1 within and among host individuals, the phylogenetics of known transmission histories, and HIV evolution and disease progression. This section illustrates the potential value of the application of HIV-1 phylogenetic analysis in understanding population dynamics, transmission risk, disease progression, and the development of antiviral drug resistance.

HIV-1 is unique among microbial pathogens, as evolutionary theory is part of daily discourse for virologists, molecular biologists, and even clinicians working with this virus. Sequencing reverse transcriptase and protease genes to identify the acquisition of mutations associated with antiretroviral drug resistance is now a routine part of clinical HIV care. The eventual development of an effective vaccine will require a better understanding of the global genetic diversity of HIV-1 and the likelihood of sequence conservation. For evolutionary biologists, this book highlights the value of HIV-1 as a model for molecular evolution research. For HIV researchers and to a lesser extent clinicians, this book summarizes the breadth of information on HIV-1 molecular biology in the context of HIV-1 evolution and emphasizes the role of molecular evolutionary biology in understanding and combating this epidemic.

John Flaherty
Department of Medicine
University of Chicago

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