Anaplasma marginale field challenge: protection by an inactivated immunogen that shares partial sequence of msp1alpha variable region with the challenge strain.

Twenty four Hereford heifers free of anaplasmosis were allotted into three groups of eight animals each and inoculated three times with adjuvant in Puck saline as control or 50 microg and 100 microg of total protein of Anaplasma marginale initial bodies from three Mexican strains which share the same variable region of msp1alpha and msp4. Inoculation with the adjuvant or the immunogen at either of the two protein doses did not induce any undesirable changes attributable to inoculation in vaccinates or controls. On day 78 post vaccination animals were released in a ranch where bovine Anaplasmosis is endemic. The A. marginale strain prevalent in this ranch shares some of the msp1alpha tandem repeats with and the strains used in the vaccine. After release, all animals became infested with Boophilus microplus ticks and flies. During the challenge period, between days 279 and 300, loss of PCV due to clinical anaplasmosis in control animals was statistically higher from vaccinated animals. Likewise, controls mean peak rickettsemia was also significantly higher (p< or =0.01) than vaccinates' rickettsemias. The antibody responses of all vaccinates after the third vaccination reached OD values above 2.0 on day 49 and were different from controls (p<0.01). IgG(2) responses from both groups of vaccinates were different from controls (p<0.01). Vaccinates which required treatment, also showed the lowest IgG(2) and substantial IgG(1) responses. After contact with the rickettsia, controls developed clinical disease and 7 out of 8 required treatment, while vaccinates in general showed no substantial changes in hematocrit or rickettsemia and only one animal in each group required treatment. Our present results show that vaccination with either 50 microg or 100 microg of protein from purified IB derived from three strains induced protection to resist the challenge with the a field strain that shares some of the tandem repeats of MSP1a.

[Evaluation of an homologous bacterin against bovine leptospirosis]. / Evaluación de una bacterina homóloga contra la leptospirosis bovina.

48 adult bovine females dividided into 6 groups were used aimed at characterizing the immune response induced in breastfeeeding cows by an homologous bacterin formulated with different adjuvants. They were intramuscularly administered 2 milliliters of a bacterin formulated with Leptospira interrogans serovars uam, wolffi, hardjo, bratislava, grippotyphosa and panama added with different adjuvants, such as aluminum hydroxide, Freud's complete adjuvant, Freud's incomplete adjuvant, liposoluble vitamins, bacterin plus disparasitization with levamisol. The control group was administred only with bacterin. Immunization took place in 2 occasions at a time interval of 28 days. Blood samples were taken every 7 days during the first month after vaccination, and every 28 days for the next 8 months. All the sera were analyzed by the microscopic agglutination test. The results were transformed into Log10 and they were analyzed by NLIN and GLM of SAS. The period of greater response was estimated by the prediction model (Wood). The bacterin did not produce alteration either in the physiological constants, or in milk production. The serovars of Leptospira interrogans that induced higher titers were uam, hardjo and wolffi. The statistical difference between treatments and between serovars was determined.