Virulence and serum-resistance in different clonal groups and serotypes of Yersinia ruckeri.

The virulence in rainbow trout (Oncorhynchus mykiss) of 32 isolates of Yersinia ruckeri, representing a range of biotypes, serotypes, and OMP-types, was examined. Virulence was assayed in fish of average weight 7.7 g by bath challenge for 1 h with approximately 5 x 10(7) cells per ml. Two of the six serotype O1 clonal groups of Y. ruckeri, clones 2 and 5, were virulent, whereas the other four clonal groups, clones 1, 3, 4 and 6, as well as all serotype O2, O5, O6 and O7 isolates examined, were avirulent. Analysis of susceptibility to the bactericidal effect of non-immune rainbow trout serum demonstrated an association between virulence and serum resistance. The virulent serotype O1 clonal groups were serum resistant, whereas the avirulent serotype O1 clonal groups and other serotypes were, with some exceptions, serum sensitive. The fact that some serum resistant isolates were avirulent suggested that other factors may be required for the full expression of virulence. The study also demonstrated that rainbow trout and brook trout (Salvelinus fontinalis) differ in their susceptibility to Y. ruckeri.     

Differentiation between antibodies to serotypes 1 and 2 infectious bursal disease viruses in chicken sera

The usefulness of the virus neutralization (VN) test, the enzyme-linked immunosorbent assay (ELISA), and the agar gel precipitin (AGP) test in differentiating antibodies to infectious bursal disease virus serotypes 1 and 2 was investigated. Sera examined were from chickens that were challenged with live virus or inoculated with inactivated oil-emulsion IBDV vaccines or were both challenged and inoculated. Antibodies to serotypes 1 and 2 were differentiated by the VN test but not by the ELISA, and the AGP test was less than satisfactory.     

Production and characterization of monoclonal antibodies to three infectious bronchitis virus serotypes.

Three panels of monoclonal antibodies (MAbs) were prepared against the spike (S) proteins of infectious bronchitis virus (IBV) strains Arkansas 99, Connecticut 46, and Massachusetts 41. Based on enzyme-linked immunosorbent assay (ELISA), the MAbs were grouped into three categories: 1) group-specific, which reacted with a broad spectrum of homologous and heterologous IBV serotypes; 2) serotype-specific, which reacted only with strains of the homologous serotype; and 3) strain-specific, which reacted "selectively" with only certain strains of homologous and heterologous serotypes. MAbs that displayed serotype specificity were all specific to S1 fractions of the homologous serotype, confirming that epitopes that determine virus serotype are associated with the S1 protein. An excellent correlation was found when the results of IBV serotyping by MAb-based indirect ELISA were compared with those from the conventional virus-neutralization test. This confirms that the MAbs described here will serve as valuable tools in epizootiological studies and serotype-specific diagnosis of IBV infection.     

Reactivity of cross-reacting monoclonal antibodies with canine leukocytes, platelets and erythrocytes

A panel of 380 commercially available monoclonal antibodies (mAbs) against human CD molecules from various sources was tested during the 8th Human Leukocyte Differentiation Antigen Workshop (HLDA8) for cross-reactivity on canine peripheral blood leukocytes by flow cytometry. In addition, all mAbs were used to label a 50:50 mixture of platelets and erythrocytes of the same dogs. This testing resulted in 51 cross-reacting mAbs. mAbs with specificity for CD9, CD29, CD42a, CD61, and CD41/CD61 showed cross-reactivity with canine platelets in a non-polymorphic and one mAb with the erythrocyte antigen CD235a in a polymorphic reaction pattern. Canine leukocyte-reactive mAbs included those with specificity for CD11a, CD11b, CD14, CD18, CD21, CD22, CD47, CD49d, CD49e, CD56, CD62L, CD91, CD94, and CD172a. In addition, several mAbs resulted in a staining pattern of canine cells which suggest that the canine epitope equivalents have an alternate expression pattern from that expected for humans (CD1a, CD35, CD44, CD45, CD75s, CD81). In summary, this study confirmed the reactivity of previously described cross-reactive mAbs with canine cells and resulted in the characterization of mAbs recognizing so far undetectable canine CD molecules.     

Specificity in response of vaccinated swine and mice to challenge exposure with strains of Erysipelothrix rhusiopathiae of various serotypes.

Swine and mice were vaccinated with standard erysipelas adsorbate bacterins made from Erysipelothrix rhusiopathiae of serotype 2 and were subsequently exposed to pathogenic strains of E rhusiopathiae, serotypes 1, 2, 4, 9, 10, and 11. Response to challenge of immunity in swine was determined by presence of urticarial lesions at the sites of intradermal injection of culture; response in mice was determined by the quantal (live-dead) method. After vaccination with standard bacterins, swine and mice were significantly more susceptible (P less than of equal to 0.01) to infection with strains of serotypes 9 and 10 than with strains of serotypes 1, 2, 4, or 11. An adsorbate bacterin made from the challenge strain of serotype 10 induced specific immunity to homologous challenge exposure in swine but not in mice. Bacterins made from the other challenge strains induced little or no immunity.     

Serological differentiation of five bluetongue virus serotypes in indirect ELISA.

The serological reactivity in indirect ELISA of five different bluetongue virus (BTV) serotypes (4, 10, 15, 16 & 20) was compared using polyclonal antisera raised against virus particles and an outer structural protein, VP2. Rabbit and sheep antisera against BTV-10 produced higher ELISA values with their homologous antigens than with heterologous serotypes. A hyperimmune rabbit serum specific for virus particles was able to distinguish heterologous serotypes from each other, but a sheep serum from an infected animal was not. An antiserum directed against VP2, the protein responsible for serotype specificity in neutralization tests, was not serotype-specific in ELISA and cross-reacted with other serotypes. The discriminatory ability of a BTV-4 antiserum was improved by cross-absorption with heterologous antigens. This greatly reduced the ELISA signals with heterologous serotypes and produced an antiserum that was effectively serotype-specific.     

Failure of maternally derived infectious bursal disease antibodies to serotypes 1 and 2 to protect against heterologous virus

Chicks with maternally derived infectious bursal disease antibodies to either serotype 1 or 2 were challenged at intervals between day-old and 7 weeks of age using the homologous and the heterologous viruses. With both serotypes good protection was demonstrated against the homologous challenge, but not against the heterologous virus.     

Isolation, serotypes, and virulence-associated properties of Yersinia enterocolitica from the tonsils of slaughter hogs.

The objectives of this study were to determine the carriage rate of Yersinia enterocolitica in the tonsils of slaughter hogs, and to characterize them with regard to phenotypic and virulence-associated properties. Of 202 pigs examined from an abattoir in Prince Edward Island, 85 were culture positive for Y. enterocolitica. Sixty-seven percent of isolates belonged to serotype O:3, and 20% were serotype O:5. All isolates produced urease and 95% of O:3 isolates showed virulence-associated characters of autoagglutination at 37 degrees C and lack of fermentation of esculin and salicin. All isolates were tested for crystal violet binding, calcium dependency, and virulence plasmids. Eight isolates (5 belonging to serotype O:3, 2 belonging to O:5,27, and 1 belonging to O:7,8) were tested in addition for the production of heat-stable enterotoxin (ST), and iron-chelating siderophores. Of the 57 O:3 isolates, 93% were positive for crystal violet binding and calcium dependency and 98% possessed a 40-45 MDa plasmid. Four of the 5 O:3 isolates tested for ST related to Escherichia coli STa in a commercial enzyme immunoassay were positive. Six of the 8 isolates belonging to 3 different serotypes produced large orange halos around the colonies on a chrome-azurol-s agar assay medium, for siderophores. Antimicrobial susceptibility tests of all 85 isolates against 16 drugs showed 100% susceptibility against 12 drugs, including trimethoprim-sulfamethoxazole and tetracycline.     

Identification of the cross-reacting antigen among Actinobacillus pleuropneumoniae strains of serotype 1, 9 and 11 by use of monoclonal antibodies.

Two monoclonal antibodies (MAbs), lMAb-1 and lMAb-5, against Actinobacillus pleuropneumoniae serotype 1 were obtained. In enzyme-linked immunosorbent assay-inhibition tests with whole cell antigens obtained from serotype 1 to 12 strains of A. pleuropneumoniae, lMAb-1 reacted to only a serotype 1, strain 4074. The epitope recognized by lMAb-1 was a carbohydrate sensitive to periodate oxidation and resided on capsular polysaccharide (CP) of A. pleuropneumoniae serotype 1. On the other hand, lMAb-5 reacted with serotype 1, 9 and 11 strains at the same degree and its epitope was found to be located on O-polysaccharide of serotype 1, 9 or 11 lipopolysaccharide (LPS). These results showed that CP was one of the serotype-specific antigens of A. pleuropneumoniae, and that O-polysaccharide of LPS obtained from serotype 1, 9 or 11 strain was the cross-reacting antigen among these strains.     

Detection of antibodies against Actinobacillus pleuropneumoniae serotypes 1, 2, 5 and 7 using the immunohistochemical staining.

Whole cells of Actinobacillus pleuropneumoniae (A. pleuropneumoniae) serotype 1, 2, 5 or 7 attached to fibrins were fixed in 10% neutral buffered formalin and embedded in paraffin. The sections on a slide glass were stained by the avidin-biotin complex immunoperoxidase (ABC) method. Test sera were applied to sections as primary antibodies. The serum antibodies against A.pleuropneumoniae (serotypes 1, 2, 5 and 7) were measured by the ABC method and complement fixation (CF) test. There was good correlation between the ABC and CF tests. The present results indicate that the immunohistochemical staining is as useful as the CF test for the detection and quantification of antibody in swine sera.     

Contribution to the morphology and biochemistry of mustelide blood. 1. Blood specimen collection in various mustelides with special reference to the use of the tissue adhesive "Fimomed"]

An account is given of various techniques of blood sampling in the context of certain mustelids, including cardiopuncture, amputation of tail tip, talon cutting, incision of the ear vein, puncture of the jugular or femoral vein, and catheterisation of the abdominal aorta. Reference is made to details of use of all techniques, characteristics, advantages and potential setbacks, and preferable use of some of the tested methods to collect blood from mustela and martes species. Blood collection from the abdominal aorta may be helpful in obtaining no-haemolysis and no-additive plasma for biochemical multi-screening. Biochemical, pharmacological, and toxicological follow-up checks may be feasible under certain conditions following surgical exposure of the external jugular vein. The use of "Fimomed" (n-butylcyano-acrylate), a tissue adhesive, may help to reduce effort in terms of time and material and consequently, rationalise veterinary hygiene action as a whole, provided that the conditions for its application are observed. The skin adhesive is properly applicable to skin lesions of mustelids. A combination of suturing with adhesive should be used to close laparotomy wounds for better mechanical strength of the abdominal wall. Possible applications of "Fimomed" should be tested with other species as well.