Dermal responses to Ostertagia ostertagi in Ostertagia ostertagi- and Cooperia punctata-inoculated calves

Calves harboring patent Ostertagia ostertagi or Cooperia punctata were given intradermal injections of O ostertagi 3rd-stage larval antigen. The initial injections were followed 30 days later by a 2nd series of injections. Skin thickness was measured at injection sites for 72 hours after injection. Selected injection sites including saline solution control sites were biopsied at 30 minutes, at 3, 24, 48, and 72 hours, and at 30 days after injection. After the 1st series of injections, there was a clear distinction in dermal reactions between O ostertagi-inoculated calves and C punctata-inoculated calves; after 24 hours, reactions were not seen in the C punctata-inoculated calves. Marked dermal reactions occurred in the O ostertagi-inoculated calves. The reactions at 30 minutes and 3 hours were characterized by slight-to-extensive infiltration of neutrophils and dermal edema. The 24-hour cellular reaction was principally due to neutrophil and eosinophil infiltration with edema and necrosis. Reactions at 48 to 72 hours were due to eosinophils and perivascular accumulations of macrophages and lymphocytes. Necrosis, neutrophils, and edema were present in foci where fragments of nematodes were located. On reinjection, a clear distinction in dermal reactions between calves was not seen based on the type of nematode infection. Thirty days after dermal inoculation, large nodules developed at the site of the initial antigen injection. The nodules were characterized by marked intradermal proliferation of lymphocytes in a follicular pattern with occasional macrophages and rare multinucleated giant cells.     

Effect of size and temperature on the quantity of immunoglobulin in channel catfish, Ictalurus punctatus

Concentrations of serum immunoglobulin (Ig) were determined for 30 channel catfish from pond water at 10 degrees C. These values were compared to measurements of 15 channel catfish from pond water at 30 degrees C. Channel catfish from 10 degrees C pond water had no significant (P greater than 0.05) different Ig concentrations (mean, 398 mg/dl) than catfish from 30 degrees C pond water (mean, 367 mg/dl). Serum Ig concentrations appear not to be different in cold (10 degrees C) vs warm (30 degrees C) pond water for 37.5-45 cm catfish. Channel catfish, 7.5-15 cm (n = 24) had significantly (P less than 0.05) lower Ig levels (mean, 104 mg/dl) than catfish either 7.5-25.5 cm (n = 57, mean, 232 mg/dl) or 37.5-45 cm (n = 45, mean, 388 mg/dl). Also, catfish 17.5-25.5 cm had a significantly (P less than 0.05) less Ig than catfish 37.5-45 cm. The concentrations of serum Ig increase with size (P = 0.0001) of catfish. The mean Ig concentration for 7.5-45 cm catfish (n = 126) was 263 mg/dl. The Ig concentration range was 44 to 650 mg/dl of serum.     

Assay performance during validation of freezing channel catfish Ictalurus punctatus (Rafinesque) infected with a Gram‐negative bacterium

Recovery of bacteria from infected fish during population sampling can be affected by factors including the type of assay, method of specimen preservation and concentration of bacteria present. Consequently, before use in field sampling, methods should be validated. The three objectives of this study were, first, to determine whether a channel catfish Ictalurus punctatus (Rafinesque) fingerling classified as positive for Gram‐negative Edwardsiella ictaluri infection according to bacterial culture before freezing was also classified as positive after freezing, second, to determine how direct culture from the kidney (DIRECT), culture of homogenate (HOMOG) and standard PCR (PCR) agree with bacterial culture in terms of classifying fish as positive or negative and third, to estimate diagnostic sensitivity (dSe) and diagnostic specificity (dSp) for DIRECT, HOMOG and PCR. In fresh and frozen fish, as bacterial concentration decreased, the ability of each assay to detect positive fish also decreased, especially when there were <10⁴ colony‐forming units per gram (CFU g^?1) tissue. HOMOG proved to be the most reliable at correctly classifying catfish, whether they were subclinically or clinically infected. PCR assay was the least reliable. Overall, values for this study population for dSe were 0.66, 0.92 and 0.43, and for dSp were 0.86, 0.91 and 0.95, for DIRECT, HOMOG and PCR respectively.     

Visualization of eosinophil chemotactic factor in abomasal tissue of cattle by immunoperoxidase staining during Ostertagia ostertagi infection

Eosinophil chemotactic factor (ECF) was localized predominantly in the intestinal cells and lateral hypodermal cords of developing fifth stage larvae (L5) of Ostertagia ostertagi within abomasal tissue cross-sections by peroxidase in an antibody sandwich technique using monoclonal antibody to ECF. Cooperia oncophora larvae in tissue cross-sections did not stain using this technique. These experiments demonstrate that ECF is localized in Ostertagia ostertagi organelles and is probably released by the developing L5 into the abomasal tissue surrounding the parasitized gland. The presence of ECF within O. ostertagi larvae in situ and the results of previous experiments demonstrated in vitro and in vivo ECF chemotactic activity help to explain why eosinophils are observed histologically in abomasal tissues from cattle with ostertagiasis.     

Luminol-dependent chemiluminescence analysis of the variables of the phagocytic response by canine granulocytes

Variables which influence the oxygen-dependent chemiluminescence (CL) response of canine polymorphonuclear leukocytes (PMN) to zymosan were examined in a luminol-dependent CL assay system. Maximal CL responses were obtained when 5 × 10⁶ canine PMN, isolated from heparinized blood, were assayed at 37° C in a Luminometer. The response was enhanced by the addition of 0.05 mM Luminol and inhibited by the addition of 0.06 mM sodium azide and 60 ug superoxide dismutase. Repeatability on a given day was very good; however, day to day variations in CL activity prevented direct comparison of phagocytic activity between days. Opsonization of zymosan in equine serum significantly reduced the CL response by canine PMN as compared to opsonization of zymosan in autologous or homologous canine serum and bovine serum. The present results show that luminol-dependent CL analysis can be used to measure phagocytosis by canine granulocytes in a luminometer and has potential use in clinical situations.     

Cell-mediated immune response after Brucella abortus S19 vaccination.

Cell-mediated immunity to Brucella abortus S19 vaccine was measured in young heifers by the microassay for stimulation of protein synthesis (SPS) with [3H]leucine and the skin test for delayed hypersensitivity. Brucella melitensis protein allergen and a crude B abortus S19-soluble antigen were compared in the SPS test. The SPS test was negative in 5 unvaccinated heifers and strongly positive in 3 twice-vaccinated steers. However, the SPS test was positive only in 13 of 30 S19-vaccinated heifers and the delayed hypersensitivity in 9 of 29 S19-vaccinated heifers. The 2 tests gave good agreement. Vaccination-induced residual antibody titers were partly correlated with the outcome of the tests used to measure cell-mediated immunity.     

Serum antibody response to soluble extract of the third-larval stage of Ostertagia ostertagi in cattle

Serum IgG, IgM, and IgA antibody responses against L₃ antigens of Ostertagia ostertagi were monitored by enzyme-linked immunosorbent assay (ELISA) after one, two or multiple sequential inoculations of this nematode in calves. Following the first infection, antibody levels did not change. After a second inoculation, IgG increased significantly (P < 0.05) after 2 months. IgG was not significantly increased 1 month after challenge inoculation. IgM and IgA antibody levels did not change following the first or second inoculations of L₃. IgG antibody levels rose only slightly following multiple sequential inoculations with infectious L₃.

Results indicate that calves with ostertagiasis have very weak serum antibody responses to L₃, and these appear to be of little value in detection of the infection in these animals.     

Flavobacterium columnare genomovar influences mortality in channel catfish (Ictalurus punctatus)

Flavobacterium columnare, causal agent of columnaris disease, is pathogenic to many species of freshwater fish throughout the world. The United States channel catfish (Ictalurus punctatus) aquaculture industry is severely impacted by columnaris disease. The majority of the F. columnare isolates recovered from diseased channel catfish belonged to either genomovars I or II. The objective of the present study was to determine if differences existed in the ability of these genomovars to induce mortality in channel catfish. Single strand conformation polymorphism analysis (SSCP) was used to ascribe the isolates used in this study to the appropriate genomovar. Immersion challenge experiments (15min immersion exposure to approximately 5x10(5) to 1x10(6) CFU/mL) were carried out to assess virulence of genomovar I and II isolates to channel catfish. The results demonstrated that genomovar II (n=4) isolates were significantly (P<0.05) more virulent to channel catfish fry (92-100% mortality) than genomovar I (n=3) isolates (0-46% mortality). In vivo adhesion of the genetically characterized F. columnare also correlated (r2=0.73) to increased mortality in the challenged fry. In fingerling channel catfish, significantly higher mortality (P<0.05) resulted with genomovar II isolates ALM-05-182 and ALG-00-530 as compared to all the genomovar I isolates (n=3). Mortality of genomovar II isolate BGFS-27 with similar to genomovar II isolate (ALG-00-530) and two genomovar I isolates (ALM-05-53 and 140). The results suggest that although both genomovars are present in the aquatic environment, genomovar II appears to be more pathogenic for channel catfish.