the chimeric proteins , and a protential vaccine and diagnostic reagent comprising gag - env chimeric protein particles are disclosed . the preparation comprises linking gag of hiv - 2 to env to form the chimeric gene , inserting the obtained chimeric gene into the dna of a baculovirus , infecting insect cells or insect host with the resulting recombinant virus , culturing it and purifying the obtained chimeric protein . the gag chimeric protein of hiv according to the present invention retains both antigenic and immunogenic properties .