oa Editorial [Hot topic: Animal Lentiviruses (Guest Editors: Jodi K. Craigo and Ted M. Ross)]

According to the UNAIDS 2008 global fact sheet an estimated 33 million people were living with HIV in 2007. This same year saw approximately 2.7 million new HIV infections as well as 2 million AIDS-related deaths. For over twenty years, regardless of our growing understanding of the many characteristics of HIV, ultimate control of the virus and its disease still eludes us. Since its original classification in the early 1980s we have been struggling to defeat this diminutive giant. This original classification of HIV as a lentivirus and the causative agent of AIDS was due to its morphological and serological resemblance to the ungulate lentiviruses that were more broadly known at the time. In fact, historically, the ungulate lentiviruses have been under investigation longer than any other virus group as the first viral etiology ascribed to an animal disease was an animal (ungulate) lentivirus. Animal, or more specifically non-primate, lentiviruses as a group are found endemically worldwide and infect a broad array of species. The lentivirus group was originally categorized as a distinguished subset of the family Retroviridae in the mid-1900s from classifications of maedi-visna viruses which, unlike the typical viruses characterized at that time, required months and years to manifest disease (lenti, from Latin, meaning slow). The diseases associated with animal lentiviral infections range from benign and subclinical to severely debilitating and lethal. During the past two decades since the discovery of HIV, research on the animal lentiviruses has increased markedly in an attempt to model the viral replication dynamics and disease processes associated with HIV-1/AIDS. In this issue of Current HIV Research these notable groups of non-primate animal lentiviruses are reviewed: beginning with the small ruminant lentiviruses (SRLV, previously referred to either as maedi-visna and/or caprine arthritis viruses), equine infectious anemia virus (EIAV), feline and bovine immunodeficiency viruses (FIV and BIV, respectively) and ending with the most recently identified lentivirus, Jembrana disease virus (JDV). The first two reviews cover the SRLV members of the lentivirus family. Leroux, Minardi, and Mornex introduce the SRLV with discussions of the reclassification of the lentivirus group with an emphasis on mechanisms leading to disease. In the second SRLV review, Blacklaws and Harkiss provide a comprehensive comparison between this mucosal pathogen and its cousin HIV highlighting the similarities of restricted replication and virus latency. Three reviews cover another of the ungulate lentiviruses, EIAV. Payne and Fuller discuss identification of viral pathogenesis determinants and how this work can be utilized to evaluate virus-host interactions. The second review by Carpenter and Dobbs describes using EIAV to evaluate the specific contributions of accessory proteins, particularly Rev, to in vivo viral variation and how studies such as these can be used to develop treatments for the prevention of lentiviral infections. Craigo and Montelaro overview studies in this equine lentivirus animal model of viral pathogenesis and vaccine development surveying the effects of envelope protein variation on both viral persistence and vaccine efficacy. Two reviews assess the feline member of the lentiviruses, FIV. Elder and colleagues highlight both the strengths and shortcomings of the FIV/cat model, particularly in regards to the development of antiviral drugs. The second FIV review by Yamamato and associates discuss the only commercially available lentiviral vaccine, Fel-O-Vax, its T-cell-related efficacy, and how these studies are being used to define the prophylactic epitopes needed for an HIV-1 vaccine for humans. The last two reviews cover the bovine lentiviruses, BIV and JDV. Corredor, St-Louis, and Archambault assess the biological and molecular aspects of BIV highlighting the regulatory/accessory viral genes involved in virus expression. In the last review, Desport and Lewis overview the current research on JDV covering the dynamics of viral replication, tropism and disease, molecular analysis of the viral genome and mRNA transcripts, and the current status of vaccine development and diagnostic assays. This issue gives a broad overview of the history and current state of research on the animal lentiviruses. As co-editors of this issue of Current HIV Research, we are very grateful for the time and effort that all of the authors committed to each review article. Furthermore, we hope that the reader will be stimulated by this collection of insightful review articles.