Characterization of Anti-Dal Alloantibodies Following Sensitization of Two Dal-Negative Dogs

Since its discovery, the immunogenicity of the Dal blood type has not been further investigated. The aim of this study was to better characterize anti- Dal alloantibodies produced following sensitization of Dal-negative dogs, notably their rate of appearance, the agglutination titer over time, and their immunoglobulin class. A secondary objective was to obtain polyclonal anti- Dal alloantibodies to increase the availability of Dal blood typing. Of 100 healthy laboratory Beagles tested, 2 Dal-negative dogs were identified as recipients. Ten healthy Dal-positive dogs were investigated as potential blood donors. All dogs were extensively blood typed for DEA 1, 3, 4, 5, and 7, as well as for Dal. Then, the recipients were transfused uneventfully with 10 ml/kg of Dal-positive but otherwise compatible packed red blood cells. Posttransfusion blood samples were collected routinely over a minimum of 1 year. Using a gel column technology, anti- Dal alloantibodies were detected as early as 4 days posttransfusion and remained detectable 2 years posttransfusion, with maximum agglutination titers reached at 1 and 2 months posttransfusion. The immunoglobulin class was IgG. The immunogenicity and clinical significance of the Dal blood type were confirmed. The results support the recommendations that previously transfused dogs be crossmatched starting 4 days posttransfusion and for the animal’s lifetime. The polyclonal anti- Dal antibodies produced will allow blood typing of a significant number of dogs, especially transfused dogs facing blood incompatibilities and canine blood donors.

Probiotic supplementation in diet and vaccination of hybrid surubim (Pseudoplatystoma reticulatum♀ x P. corruscans♂)

ABSTRACT: A supplementary diet with the probiotic bacteria Weissella cibaria on the efficacy of surubim hybrid immunization against a specific hemorrhagic septicemia caused by Aeromonas hydrophila was evaluated on the following treatments: fish fed a supplemented probiotic diet, vaccinated fish and vaccinated fish fed a supplemented probiotic diet, and untreated fish (control). Fish from the probiotic treatments were fed a diet containing W. cibaria for 41 days. On the 15th day of the experiment, fish from vaccine treatments were intraperitoneally vaccinated, with posterior oral booster for four days. One week after the oral booster, three fish from each experimental unit were sampled. The probiotic supplementation increased the number of thrombocytes and lysozyme concentration compared with surubim that did not receive W. cibaria in the diet. On the other hand, the vaccination increased agglutination titer, lysozyme concentration, and antimicrobial activity compared with surubim that were not vaccinated. However, there was no interaction between diet with probiotics and vaccination in the surubim hybrid in the analysed parameters.

Hematological and immunological responses of Nile tilapia after polyvalent vaccine administration by different routes

The efficacy of a polyvalent bacterin vaccine against Aeromonas hydrophila, Pseudomonas aeroginosa and Enterococcus durans administered by different routes in Nile tilapia was assessed by analyzing hematological and immunological parameters 7 and 21 days after vaccination. Treatments consisted of: non-vaccinated tilapia; tilapia vaccinated by intraperitoneal injection with 2x10(8) formalin-inactivated bacteria·mL-1; tilapia vaccinated orally with 2x10(7) formalin-inactivated bacteria·g-1, feed for 5 days; tilapia vaccinated by immersion bath in 2x10(7) formalin-inactivated bacteria·mL-1, for 20 minutes. Vaccinated fish groups presented higher hematocrit, number of erythrocytes and leukocytes than the non-vaccinated group. Serum agglutination titer of intraperitoneally vaccinated fish was higher on both evaluation periods for the three bacteria strains. Only on day 21 post-vaccination fish from the oral and immersion vaccination groups presented higher serum agglutination titer than the non-vaccinated fish for A. hidrophyla and E. durans. Serum antimicrobial activity in vaccinated fish was higher for P. aeroginosa and E. coli than in non-vaccinated fish on both evaluation periods. The different vaccine administration routes stimulated hematological and immunological responses in Nile tilapia 21 days post-vaccination, but intraperitoneal vaccination presented higher total number of leukocytes, lymphocytes and serum agglutination titer.

Avidin attachment to biotinylated erythrocytes induces homologous lysis via the alternative pathway of complement

Noncovalent attachment of avidin to the membrane of prebiotinylated red blood cells (RBCs) induces lysis via the alternative pathway of complement (APC). Lysis is not species-dependent; RBCs from humans, rabbits, rats, and sheep were lysed with both autologous and all heterologous sera. Both biotinylated and native cells were not lysed. Lysis was observed at an avidin surface density of about 10(5) molecules per cell. Acylation of avidin prevents lysis and decreases the positive charge of the avidin. Lysis depends on the length of the cross-linking agent used for the biotin attachment to the membrane. An increase in the length of the cross-linking agent was accompanied by an enhancement of the lysis and the agglutination titer of biotinylated RBCs in a solution of avidin. It is suggested that avidin attachment induces some transformations of the cell membrane that lead to the conversion from “APC nonactivator” cells to “APC activator” cells. The interaction of avidin with membrane APC-restrictors (decay-accelerating factors, type 1 receptor for complement, homologous restriction factor, and others), the charge of avidin, and its cross-linking ability in lysis are discussed. It is proposed that membrane rearrangement induced by multipoint avidin attachment to biotinylated membrane is the main reason for avidin-induced elimination of APC restriction.

Avidin attachment to biotinylated erythrocytes induces homologous lysis via the alternative pathway of complement

Noncovalent attachment of avidin to the membrane of prebiotinylated red blood cells (RBCs) induces lysis via the alternative pathway of complement (APC). Lysis is not species-dependent; RBCs from humans, rabbits, rats, and sheep were lysed with both autologous and all heterologous sera. Both biotinylated and native cells were not lysed. Lysis was observed at an avidin surface density of about 10(5) molecules per cell. Acylation of avidin prevents lysis and decreases the positive charge of the avidin. Lysis depends on the length of the cross-linking agent used for the biotin attachment to the membrane. An increase in the length of the cross-linking agent was accompanied by an enhancement of the lysis and the agglutination titer of biotinylated RBCs in a solution of avidin. It is suggested that avidin attachment induces some transformations of the cell membrane that lead to the conversion from “APC nonactivator” cells to “APC activator” cells. The interaction of avidin with membrane APC-restrictors (decay-accelerating factors, type 1 receptor for complement, homologous restriction factor, and others), the charge of avidin, and its cross-linking ability in lysis are discussed. It is proposed that membrane rearrangement induced by multipoint avidin attachment to biotinylated membrane is the main reason for avidin-induced elimination of APC restriction.

An agar–gel immunodiffusion test for detection of Brucella antibodies in human serum

A comparison was made of results obtained with a Brucella agar–gel immunodiffusion (AGID) test and the standard tube-agglutination test on 612 human sera. Agreement between the tests was 97% when the titer was 1:160 or higher. Of 448 sera that showed no agglutination titer, 447 were negative with the AGID test. Results of the AGID test were also compared to those obtained with the 2-mercaptoethanol (2-ME) agglutination test on 148 sera that demonstrated a standard tube-agglutination titer of 1:20 or higher. All sera with a 2-ME-agglutination titer of 1:40 or higher were positive with the AGID test. Of 123 sera that showed no 2-ME-agglutination titer. 21 were positive with the AGID test. Two of these 21 sera were obtained from patients with bacteriologically proven brucellosis, and eight were from abattoir employees with suspected but not bacteriologically proven brucellosis.

Humoral antibody response to cattle to formalinized Staphylococcus aureus vaccine

Five cows were inoculated intradermally with formalinized Staphylococcus aureus suspension in Freund's complete adjuvant and the development of the humoral antibody response was followed as judged by the agglutination titer of sera, at various intervals post inoculation. Highest titers were observed at 78–87 days post inoculation. Agglutinating activity was found in IgM and IgG fractions (IgG1 and IgG2) of both serum and colostrum. The agglutinating activity of colostrum was significantly higher at 12 than at 24 and 36 h, post partum. However, no such activity was detected in either normal cow serum or colostrum against S. aureus.