The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.

A study was conducted to compare immunogenicity of a Brucella abortus lipopolysaccharide (LPS) and the duration of infection in 5 strains of mice. Mice of strains CBA/NJ, BALB/c, CD-1, C3H/HeN, and C3H/HeJ were allotted into 2 large groups (vaccinated with proteinase K-treated LPS or nonvaccinated) and 6 subgroups based on the intervals between challenge exposure to B abortus strain 2308 and the week the response data were obtained. Criteria used in comparing responses between the various strains of mice as well as betweeen vaccinated and nonvaccinated mice were splenomegaly, colony-forming units (CFU) from spleens, and antibody titers. Responses were evaluated at 1, 2, 3, 5, 8, and 12 weeks after challenge exposure. Results indicated that all strains of mice became infected and maintained infection throughout the 12-week period, the percentages of mice infected were significantly (P less than 0.05) less in vaccinated mice for the first 5 weeks after challenge exposure, and there were no direct correlations between increased immunoglobulins (IgM and IgG titers) and reduction in CFU. Vaccinated mice of strains BALB/c, CD-1, C3H/HeN, and C3H/HeJ had increased titers when challenge exposed and also had significantly (P less than 0.05) smaller spleens and lower CFU. Vaccinated CBA/NJ mice did not have marked antibody titers. The overall results indicated that vaccination with LPS offers some initial protection against B abortus strain 2308 infection, but this protection disappears gradually and in various degrees in the 5 strains of mice studied.

Uterine response to inoculation with Streptococcus zooepidemicus organisms, 51Cr-labeled 15-micromoles microspheres, and charcoal was evaluated in 9 mares (4 resistant and 5 susceptible to endometritis) to determine mechanical and cellular clearance rates during the early postovulatory period. Mares were inoculated at estrus prior to ovulation during estrous cycles 1, 3, and 5. Uterine swab specimens for aerobic and anaerobic bacteriologic culture and serum for progesterone determination were obtained on postovulation day 3 during estrous cycle 1, on the day of ovulation during estrous cycle 3, and on postovulation day 5 during estrous cycle 5. Immediately thereafter, the uterus was irrigated with 50 ml of sterile physiologic saline solution containing tracer amounts of 125I-labeled human serum albumin. Streptococcus zooepidemicus was isolated from 10 of 15 (67%) uterine specimens collected from susceptible mares and incubated aerobically. Escherichia coli also was isolated from 2 of the 10 specimens incubated aerobically. Anaerobic bacteriologic culture of specimens from all mares yielded no growth. Chromium-labeled microspheres were recovered twice from 2 susceptible mares, on day 0 and day 5. Charcoal was retained in 5 specimens collected from 3 susceptible mares. Bacteriologic culture of specimens from resistant mares did not yield growth. On day 0, chromium-labeled microspheres and charcoal were recovered once from 1 resistant mare. Mares susceptible to end ometritis accumulated more fluid within the uterine lumen after ovulation than did resistant mares (mean +/- SEM, 52.73 +/- 15.22 ml and 7.41 +/- 1.96 ml, respectively; P less than 0.01). From this study, it appeared that uterine cellular and bactericidal mechanisms are dysfunctional during the early postovulatory period. However, there appeared to be no disruption of the mechanisms responsible for mechanical clearance of materials inoculated in the uterus.

Immunodeficiency in neonatal and young pigs was studied in terms of T-cell function. Generalized T-cell deficiency did not exist in young pigs on the basis of the in vitro response of blood mononuclear cells to a polyclonal T-cell mitogen, phytohemmagglutinin. However, immunodeficiency that extended from birth up to 4 weeks, was observed in serum antibody concentration and in vitro proliferative responses of blood mononuclear cells from young pigs exposed to a low antigen dose of a T-cell dependent antigen, egg white lysozyme. The low in vitro proliferative response to lysozyme was not attributable simply to a lack of interleukin-2 production, because supplementation with human interleukin-2 did not enhance the in vitro cellular response. Also, pokeweed mitogen-stimulated B cells from young pigs up to the age of 5 to 6 weeks produced immunoglobulin concentration, which also was not affected by the addition of human interleukin-2 to the in vitro cultures. The blood mononuclear cells obtained from pigs within the first 5 to 6 weeks after birth and incubated with monoclonal antibodies reactive to all T cells (MSA4), helper T cells (74-12-4) or suppressor/cytotoxic T cells (76-2-11) did not yield consistent excess of suppressor/cytotoxic T cells. This observed immunodeficiency cannot be attributed to a simple lack of functional T cells or to an excessive number of suppressor/cytotoxic T cells, but may be a property of the ability of specific T-cell clones to respond t o low concentration of T cell-dependent antigens or may be attributable to the induction of a suppressor T-cell population in response to in vitro stimulation with the polyclonal T-cell-dependent pokeweed mitogen system.

Serum trypsinogen concentration was studied in 6 adult mixed-breed dogs randomly fed diets containing 6.8, 31.4, or 39.7% protein (dry weight) for 3 weeks each. Blood was collected on days 20, 21, and 22 of each feeding period, and serum trypsinogen concentrations were determined by radioimmunoassay of trypsin-like immunoreactivity (TLI). Mean serum TLI concentrations for each dog fed each diet were compared. A significant (P < 0.05) positive linear relationship (P < 0.02) was determined between serum TLI concentrations and the percentage of dietary protein. Mean serum TLI concentrations for each dog fed all diets ranged from 5.7 to 20.2 microgram/L.

Possible immunomodulation by low-level infection with Ostertagia ostertagi was studied in 4-month-old calves. Six groups of 4 calves each were subjected to the following regimes: group 1--nonparasitized controls; group 2--nonparasitized, but challenge exposed at day 64 with Brucella abortus strain 19 vaccine (BA) and at day 78 with IV administration of a soluble third-stage larval (L3) antigen preparation of O. ostertagi (OAG); group 3--nonparasitized, but challenge exposed at day 78 with 75 X 10(3) L3 of O ostertagi; group 4--continuously parasitized by weekly dosing with 30 X 10(3) L3 of O ostertagi; group 5--continuously parasitized by weekly dosing with 30 X 10(3) L3 of O ostertagi, then challenge exposed on day 64 with BA and on day 78 with IV inoculation of OAG; and group 6--continuously parasitized by weekly dosing with 30 X 10(3) L3 of O ostertagi, then challenge exposed on day 78 with 75 X 10(3) L3 of O ostertagi. Over the initial 10 weeks of the study, nonparasitized calves, (groups 1, 2, and 3) had higher body weight, blood lymphocyte (BL) response to phytohemagglutinin (PHA), and significantly (P less than 0.05) higher feed consumption and lymphocyte numbers, whereas parasitized calves (groups 4, 5, and 6) had higher BL responses to pokeweed mitogen (PWM) and significantly (P less than 0.05) higher neutrophil and eosinophil numbers, plasma pepsinogen (PP) values, and BL response to OAG. During the challenge-exposure period (weeks 10 through 13), group-5 calves had significantly (P less than 0.05) higher eosinophil numbers and PP values for week 11 (BA challenge exposure) and for week 13 (OAG challenge exposure) than did group-2 calves, but differences were not observed in BL responses to PHA, PWM, and OAG. Oral L3 challenge exposure at week 13 induced significantly (P less than 0.05) lower lymphocyte numbers, higher eosinophil numbers (P less than 0.05), and higher PP values, but lower BL response to PHA, PWM, and OAG in group-6, compared with group-3 calves. In continuously parasitized calves, comparison of IV OAG challenge exposure with oral L3 challenge exposure indicated that group-6 (L3) calves has significantly lower (P less than 0.05) lymphocyte numbers and higher PP values than did group-5 (OAG) calves. Results of ELISA revealed significantly (P less than 0.05) higher antibody titer to OAG in parasitized calves, compared with nonparasitized calves. Abomasal mucosal pathologic changes were most severe in the continuously parasitized calves. Calves of groups 4, 5, and 6 had thicker mucosae (edema), significantly (P less than 0.05) higher eosinophil numbers, and higher globule leukocyte and mast cell numbers in the fundic and pyloric regions than did calves of groups 1, 2, and 3. Calves of groups 4, 5, and 6 also had significantly (P less than 0.05) larger abomasal lymph node masses than did nonparasitized calves. In group-1 calves, nodes had the lowest mass. Differences were not observed among groups for lymphocyte responses to proliferative and suppressive assays performed on the abomasal lymph node lymphocytes.

A study was conducted to establish baseline data on Brucella abortus infection induced in 5 strains of mice (CBA/NJ, BALB/c, CD-1, C3H/HeN, and C3H/HeJ). The strains were compared on the basis of immunologic, histopathologic, and bacteriologic responses. There were 4 treatment groups for each strain of mice: (1) vaccinated with homologous lipopolysaccharide and challenge exposed to B abortus strain 2308; (2) not vaccinated but challenge exposed; (3) vaccinated but not challenge exposed; and (4) not vaccinated and not challenge exposed. Results indicated that mice can be used for comparative studies on the pathogenesis and immunogenesis of B abortus infections; strains of mice may vary in their responses to Brucella infection, regardless of their vaccination status. Bacteriologic and immunologic responses in mouse strains BALB/c, CD-1, C3H/HeN, and C3H/HeJ, but not those of CBA/NJ, were extrapolative among strains.

The infectivity and immunogenicity of Anaplasma marginale grown in a tick cell culture from embryonic Dermacentor variabilis ticks were assessed in splenectomized and intact calves, respectively. Culture 1 consisted of the cell line inoculated with midguts of adult ticks infected with the Mississippi isolate of A marginale and dissected 5 to 10 days after repletion and detachment from an experimentally infected calf. Cultures 2 and 3 consisted of the cell line inoculated with midguts of ticks infected with the Virginia isolate of the organism. Inoculum for culture 2 was derived from nymphal ticks dissected 5 to 10 days after repletion and detachment from the infected calf; inoculum for culture 3 was midguts from adult ticks that were fed as nymphs, allowed to molt in the laboratory and dissected 21 to 24 days after molting. In trial 1, cultures 1, 2, and 3 were maintained at pH 6.9 and incubated at 28 C; in trial 2, cultures 1 and 3 were maintained at pH 7.4 and incubated at either 28 C or 37 C. Cultures 1, 2, and 3 failed to induce infection when injected IV and SC into 6 calves in 2 separate trials. Prechallenge sera from these calves reacted with 2 purified Anaplasma antigens in the ELISA, but failed to react in the complement-fixation test. Results of a trial to use cultures 1 and 3 in combination with an oil-in-water adjuvant to immunize intact calves against A marginale were inconclusive. However, prechallenge sera from immunized calves reacted with the 2 purified Anaplasma initial body antigens in the ELISA but failed to react in the complement-fixation text. When reacted against electrophoretically separated A marginale initial body proteins disrupted by sodium dodecyl sulfate, prechallenge serums from calves used in infectivity and immunization trials reacted with a majority of the antigens precipitated by an animal experimentally infected by inoculation of infected blood. This offers additional evidence that A marginale was maintained in the tick culture for up to 11 months and that the organism in culture antigens similar, if not identical, to the erythrocytic stage of the rickettsial agent. The importance of the laboratory culture of A marginale is discussed.

Purified O chain of Brucella abortus was passively attached to polystyrene to differentiate antibody responses of cattle vaccinated with B abortus strain 19 from those of naturally infected cattle. In the indirect assay, using O polysaccharide as antigen, a single serum dilution was used and mouse monoclonal antibody to bovine L chain conjugated with horseradish peroxidase was the detection reagent. Measurable antibody was not found in sera of vaccinated cattle, except for 3 sera from cattle that were persistently infected with strain 19. Sera from 25 cattle infected with pathogenic strains contained antibody on the basis of results of indirect enzyme immunoassay, using smooth lipopolysaccharide or O chain as antigens, or results of competitive enzyme immunoassay, using the O-chain antigen. Results in sera from calves with experimentally induced Yersinia enterocolitica serotype 0:9 infection or inoculated with a low dose of B abortus strain 2308 were comparable with those in sera of cattle that were vaccinated with strain 19. The data correlated with those from competitive enzyme immunoassay, using one serum dilution and horseradish peroxidase-conjugated mouse monoclonal antibody to smooth lipopolysaccharide. On the basis of results of the indirect enzyme immunoassay, all sera (except those samples obtained before inoculation) contained antibody to smooth lipopolysaccharide.

Chicken eggs at embryonation day (ED) 18 or newly hatched chicks were inoculated with turkey herpesvirus (HVT), Marek's disease virus (MDV), or virus-free diluent and, at intervals after inoculation, tissue homogenates of virus-exposed and virus-free chickens or chicken embryos were examined for interferon (IFN) activity. Homogenates of lung thymus and spleen specimens from chickens given HVT at ED 18 had IFN activity. Activity of IFN in the lungs was studied further. Homogenates of lung specimens from chickens exposed to HVT at hatching also had IFN activity, although the concentration of IFN was lower than that in chickens given HVT at ED 18. The pathogenic isolates of MDV (JM-(MDV)), but not the atenuated (Md11/75C-(MDV)) or nonpathogenic (SB1-(MDV)) isolates, inoculates at ED 18 also induced high lung IFN activity. Exposure to a combination of HVT and SB1-MDV induced IFN activity comparable with that in chickens given HVT alone. The IFN activity in homogenates of lung specimens from virus-exposed chickens was species specific and heat and pH stable, but was destroyed by trypsin treatment. Occassionally, low IFN activity also was detected in homogenates of tissus specimens from virus-free chickens or chicken embryos. This IFN activity could have been produced constitutively or may have been induced by substances (inducers) in the environment.