Pollyanna Mafra Soares

Interference in diagnostic tests for brucellosis in cattle recently vaccinated against leptospirosis

The aim of the current study was to verify if cattle vaccinated against leptospirosis may react in diagnostic tests for brucellosis. Sixty cows were divided into 5 groups, each comprising 12 animals. Four groups were given different vaccines against leptospirosis, while the control group received only saline. Two doses of vaccine were given, as recommended by the manufacturers. Serum samples were collected on the first day of immunization (day 0) and on postvaccination days 7, 14, 21, 28, 35, 42, 49, 56, 96, and 126. All the serum samples were tested for brucellosis and leptospirosis. Twenty animals were reactive at least once to the Rose Bengal test, but by day 96, no further reactions were elicited by this test. Twenty-six samples were reactive to the Rose Bengal test, but only 7 remained positive in confirmatory tests: 1 to the 2-mercaptoethanol test, 2 to the fluorescence polarization assay, and 6 to indirect enzyme-linked immunosorbent assays. None of the samples was reactive in the complement fixation test. None of the animals in the control group was reactive. A significant difference was found between the control group and the groups vaccinated against leptospirosis, according to Fisher exact test. However, the groups were found to respond independently of the vaccine brand. The results indicate that cattle vaccinated against leptospirosis may show reactivity on screening tests for brucellosis.

Production and Evaluation of Immunoglobulin Y Anti-Brucella abortus (Vaccinal Strain B19)

Background: The immunoglobulin Y is a principal antibody current in the blood of hens, which are transferred from the maternal blood serum to the egg yolk. The extraction of IgY from the egg yolk apply animal welfare when compared to the extraction of IgG, reducing the number of animals and prevent a bleeding of hens through the extraction of the IgY from eggs, besides that IgY presenting high specificity for antigenic binding. The objective of this study was to produce specific polyclonal IgY antibodies anti-Brucella abortus by immunizing hens with B19 vaccine and evaluate their reactivity through Buffered Acidified Plate Antigen (BAPA), 2-Mercaptoethanol (2-ME) and indirect ELISA diagnostic tests. Materials, Methods & Results: Four 25-week-old White Leghorn hens were immunized, two of them comprising the control group (Group 1) with phosphate-buffered saline (PBS) with adjuvant, and the others two immunized with B19 vaccine (Brucella abortus vaccine strain B19), representing the Group 2. The immunizations occurred six times with a 15-day interval between each. Blood samples were taken biweekly (seven times); and daily, the eggs were collected for 13 weeks, the first collection of blood and eggs, performed one week before the first immunization of each group. The IgY was purified from egg yolk, using the method of dilution in acid water and precipitation with ammonium sulfate for delipidation. BAPA, 2-ME and ELISA tests performed to verify the specificity of IgY confirmed the reactivity of polyclonal antibodies specific to the antigen used both in blood serum samples and in the purified egg yolks. The hens from the control group did not present reactivity in the diagnostic tests used, which was already expected, since no antigen was used in any of their immunizations. Hens immunized with the Brucella abortus B19 vaccine produced detectable reactive antibodies in the three tests used on blood serum and IgY samples extracted from the egg yolk. In Group 2 (vaccine B19), blood serum samples started to react one week after the first inoculation, and the IgY samples extracted from the egg yolk were reagent two weeks after serum IgY appear reactivity, showing the transfer of specific antibodies to the egg yolk, was late. Discussion: Although the transfer of serum Igy to egg yolk was late when compared to others authors which found that the transovarian passage of immunoglobulin Y occurred in approximately three to six days after IgY being detected in blood serum, the results of this study showed the occurrence of the transfer of blood serum IgY anti-Brucella abortus to egg yolk of hens immunized with B19 vaccine, the same found by others researches found the same results with others antigens. Thus, it can be concluded that immunoglobulins Y produced in this study can be used as specific antibodies in diagnostic tests for the detection of the Brucella abortus antigen, in addition, this process guarantees the welfare of the animal, since it avoids bleeding and it is possible to obtain high concentrations of antibodies directly from the hen egg, which is a great advantage, because IgY can be easily isolated from the egg yolk by the precipitation technique discarding the need of invasive and painful procedures that involve bloody interventions to obtain the serum antibodies like occur in mammals for extraction of IgG.

Frequência de lesões macroscópicas em carcaças de bovinos reagentes ao teste tuberculínico

The aim of this study was to analyze the frequency of macroscopic lesions suggestive of tuberculosis in cattle reacting to the tuberculin test. Cattle of this study were from dairy herds located in the cities of Perdizes, Patos de Minas, Lagoa Formosa and Uberlândia, Minas Gerais, Brazil. We evaluated 140 cattle carcasses positive to the cervical comparative intradermal tuberculin test. During the slaughter a post-mortem inspection of carcasses was done, and the lesions suggestive of tuberculosis were recorded. We evaluated the mediastinal lymph nodes, liver, lung and carcass. Of the 140 cattle examined, 78 (55%) carcasses had some kind of macroscopic lesions suggestive of tuberculosis, 38 (49%) occurred only in the mediastinal lymph nodes, 22 (28%) in the liver and 11 (14%) in the lungs; 5 (6%) carcasses showed lesions in liver, lungs and lymph node, and 2 (4%) showed lesions in lung and lymph nodes. We concluded that lesions that were not visualized in bovine tuberculin skin test reagents may occur and are related mainly to the stage of the disease, insufficient time to detect the lesions, and nonspecific reactions to other mycobacteria.

Produção e purificação de imunoglobulinas Y policlonais anti-Leptospira spp.

The aim was to determine whether hens immunized with an inactivated suspension of Leptospira and a solution of outer membrane proteins extracted from the serovar Hardjo, could produce specific polyclonal antibodies to Leptospira, detected in ELISA assay. Eight hens White Leghorn race with 25-weeks-old were immunized, three with an inactivated suspension of Leptospira, three with a solution of outer membrane proteins (OMP) extracted from the serovar Hardjo and two controls immunized with saline. Blood samples were collected fortnightly and eggs daily. The IgY was purified from the egg yolk using the method for the delipidation of dilution with water acidic and ammonium sulfate precipitation. The ELISA assay was performed to verify the specificity of the IgY, these was possible to observe the production of specific antibody to Leptospira both in serum and purified egg yolk. The specific antibody titers peaked in the fifth week post immunization. The production of polyclonal IgY was effective for producing high titers of specific antibodies.