Background Developing an effective vaccine against human immunodeficiency virus type 1 （HIV-1） remains a grand challenge after more than two decades of intensive effort. It is partially due to the lack of suitable animal models for screening and prioritizing vaccine candidates. In this study, we aim to develop a mice model to test HIV-1 vaccine efficacy. Methods We constructed a recombinant vaccinia expressing firefly luciferase and HIV-1 Gag fusion protein based on Tiantan strain, an attenuated but replication-competent poxvirus （rTTV-lucgag）. By quantifying the luciferase activity as its read out, we defined the biodistribution of Tiantan strain poxvirus in mice inoculated intraperitoneally and attempted to apply this model to evaluate the HIV-1 vaccine efficacy. Results Our data demonstrated that the rTTV-lucgag was able to express high level of luciferase （〈106 relative luciferase units （RLU）/mg protein） and HIV-1 Gag （〉3 folds increase comparing to the control）. After intraperitoneal inoculation, this virus had dominant replication in the ovary, uterus, and cervix of mice and the luciferase activities in those organs are significantly correlated with viral titers （r^2=0.71, P 〈0.01）. Pre-immunization with an HIV gag DNA vaccine reduced the luciferase activity in ovary from （6006±3141） RLU/mg protein in control group to （1538±463） RLU/mg protein in vaccine group （P=0.1969）. Conclusions The luciferase activity in ovary could represent viral replication in vivo; this rTTV-lucgag/mice model may be suitable to assess the protective efficacy of cytotoxic T-cell responses to HIV Gag with less tedious work and high through-put.
The pandemic of human immunodeficiency virus type 1 （HIV-I） has been devastating for the last two decades in a number of developing countries and constituting a grand challenge to the public health. WHO/UNAIDS estimates that approximately 33.2 million people were living with HIV-1 infection by the end of 2007 and almost 2.5 million new infections occurred in 2007. An unprecedented scientific challenge for the AIDS vaccine community is how to develop an effective HIV vaccine that can block HIV transmission and consequently stop the continuing spread of HIV-1. The recent failure of Merck Phase II B trial alerted the HIV vaccine community that new vaccine strategies need to be more exclusively explored. In this review, we outline the basics of HIV vaccine and retrospect the history of the road to HIV vaccine in last two decades, and highlight the challenges we are currently facing and new strategies to develop HIV vaccines in this field.
