The HIV X-File OmarBagasraHIV and Molecular Immunity: Prospects for the AIDS Vaccine1999Eaton PublishingNatick MA198 pp. $42.95

which are summarized in chapter 2, emphasize the piv-grappling to devise effective vaccines against the human immunodeficiency virus (HIV). otal role in shaping HIV molecular epidemiology of multi-HIV rapidly infects and destroys CD4 ϩ T lymphocytes, ple founder effects during HIV migration among host likely following delivery from peripheral tissues or muco-populations at risk. The nature of HIV variation allows sal membranes to the secondary lymphoid organs by for efficacious ways to pose and answer epidemiological dendritic cells. Vaccine research and development strat-questions, like those concerning the spread of viruses egies have therefore tended toward bolstering humoral by different transmission routes, within different geneti-immunity (HI) and/or cell-mediated immunity (CMI) to cally defined risk groups, and in particular ecological ensure that good defenses are already in line before niches. HIV attempts to breach them (reviewed by Heilman and For such an excellent book, we miss a section on the Baltimore, Nat. Med. 4, 532–534, 1998). In general, HI evolutionary history of HIV. The continuing discussion approaches focus on producing antibody responses on the origin of HIV and HIV subtypes has been heated that can specifically neutralize viral particles or block up recently by the discovery of several HIV strains that their entry into host cells, while CMI approaches focus are unique in terms of their age and/or position in the on drawing the attention of CD8 ϩ cytotoxic T lympho-HIV phylogenetic tree. Although there seems to be no cytes (CTL) to virally infected cells. A common obstacle firm consensus on when exactly this virus was intro-to these approaches has been the unexpected variability duced into humans, most researchers agree that the of HIV epitopes both in the population and arising by human virus is relatively " young. " The timescale in the mutagenesis. midst of this debate is unprecedented—for the first time, Unfortunately, the roles played by the adaptive im-when talking about the evolutionary origin of a virus, mune responses (HI and CMI) in the course of HIV infec-we are fighting about decades, not millions of years. tion remain incompletely, and often inconsistently, de-Researchers are generally optimists, and HIV scientists fined. We know, for instance, that individuals infected are no exception: based on longitudinal observation of with HIV exhibit both of these responses in widely vary-a growing plant, we should be able to estimate its growth ing degrees throughout the disease course. Not surpris-rate and to trace back in time quite …