Abstract: A Brucella bacterium is modified by partial or complete deletion of the pgm gene, rendering the bacterium incapable of synthesizing a key enzyme in the metabolism of bacterial sugars. A live vaccine for immunization, prophylaxis or treatment of brucellosis comprises such a bacterium, either lyophilized or in a pharmaceutical vehicle. Nucleotide sequence fragments having the aforementioned deletion are disclosed, with methods for making them.

Abstract: A procedure is provided for the sex determination of embryos in mammals, that is particularly exemplified on bovines. The procedure overcomes the limitations given in former techniques. It includes a new stage of polymerase chain reaction PCR method, using specific oligonucleotides in order to amplify fragments corresponding to the sampled cells and not from false ones, spuriously produced. In this way, the necessary sensitivity is obtained. The oligonucleotides sequences are particularly selected for the procedure. The procedure is used for the sex determination of embryos in mammals, and the procedure is sensitive enough to be carried out a sample containing few cells, is highly secure, and which give positive results for both female and male sex; specially applied to bovine embryos.

Abstract: The instant invention relates to a process in which important improvements are introduced in virus production and inactivation steps, as well as in the vaccine formulation step. The virus is reproduced in animals immuno-depressed through ionizing radiations, thus making it possible to use adult host animals, not naturally sensitive to the virus, with the advantage of using all types of tissues thereof. Bacterial infections are prevented by antibiotic administration. Virus inactivation is also obtained through ionizing radiations. Radiation doses do not affect antigenic properties, as may be noted from the interpretation of the Target Theory.