The antibody responses to the capsular carbohydrate (CC) purified from Pasteurella haemolytica serotype 1 were determined by an ELISA using 135 sera from 6 calves vaccinated with phosphate-buffered saline solution, formalin-killed P haemolytica bacterins, live P haemolytica, or an extract of P haemolytica referred to as carbohydrate-protein subunit (CPS). Calves vaccinated with live P haemolytica, bacterins, or CPS developed serum antibodies to CC. Bacterins containing Freund incomplete adjuvant or Freund complete adjuvant induced higher antibody responses than did bacterins containing aluminum hydroxide. In 4 of 6 experiments, high antibody responses to CC were significantly (P less than 0.05) correlated with resistance to transthoracic challenge exposure with P haemolytica. When calves were challenge exposed with a dose of P haemolytica that was 4.5 times greater than the standard challenge exposure dose or when calves that had been vaccinated with CPS were challenge exposed, antibody responses did not significantly (P greater than 0.05) correlate with resistance to challenge exposure. The amount of serum antibodies to CPS increased significantly (P less than 0.05) when calves were vaccinated with live or killed P haemolytica or with CPS, compared with that in calves given saline solution. In 5 of 6 experiments, correlation between high antibody responses and resistance to challenge exposure was significant (P less than 0.05). The correlation between those variables was not significant (P less than 0.07) for CPS-vaccinated calves. In the ELISA, treatment of CPS with sodium m-periodate, to oxidize periodate-sensitive carbohydrate epitopes, failed to markedly alter the antibody response to CPS. However, the correlation between high antibody responses to periodate-treated CPS and resistance was significant (P less than 0.05) for all 6 experiments. In the ELISA, periodate treatment of CC, lipopolysaccharide, and CPS caused average reductions in antibody reactivity of 7.1%, 53.8%, and 34.5%, respectively. Preadsorption of sera with CC or lipopolysaccharide did not markedly reduce antibody reactivity with CPS. Preadsorption of sera with CC and reaction with periodate-treated and nontreated CPS indicatedthat for calves given phosphate-buffered saline solution vaccines, antibody reactivity was reduced 65.4%, whereas for those vaccinated with a bacterin with aluminum hydroxide, a bacterin with Freund incomplete adjuvant, or live P haemolytica, antibody reactivity was reduced 47.1%, 40.5%, and 25.0%, respectively. It was concluded that serum antibodies to CC are of some importance in resistance and that certain epitopes in CPS that are not sensitive to periodate are of importance in resistance to bovine pneumonic pasteurellosis. There are qualitative and quantitative differences among the serum antibody responses to carbohydrate epitopes for calves vaccinated with phosphate-buffered saline solution, bacterins, or live P haemolytica.

Pseudorabies is a porcine herpesvirus of major importance in the swine industry. Isoprinosine is an immunomodulating drug that has been shown to be beneficial in treating herpesvirus infections. Twenty-four 7-week-old pigs were allotted within litters to 1 of 4 groups: control, isoprinosine (ISO), pseudorabies virus (PRV), or isoprinosine and pseudorabies virus (ISO-PRV). Isoprinosine was administered daily for 16 days to the ISO and ISO-PRV groups (75 mg/kg of body weight/day, PO). Immunity in pigs in the PRV and ISO-PRV groups was challenged with pseudorabies virus (10(5) TCID50 units) on day 4. Rectal temperatures and viral excretion were monitored daily; total and differential leukocyte counts, lymphocyte response to mitogens, and interleukin-2 production were monitored every 4 days. Pigs challenge-inoculated with pseudorabies virus became ill, with the ISO-PRV group most severely affected. Rectal temperatures were high (P less than 0.05) in virally challenged pigs on days 5 to 12 and 14 to 16; isoprinosine did not alter this effect. Pseudorabies virus-infected pigs had leukocytosis (P less than 0.05) on days 12 and 16, primarily caused by neutrophilia. Concanavalin A-stimulated lymphocyte proliferation was decreased (P less than 0.06) in both PRV and ISO-PRV groups on day 12, compared with control pigs, but only in the PRV group on day 16. Pokeweed mitogen-stimulated lymphocyte proliferation was decreased (P less than 0.02) in ISO-PRV pigs on day 8 of the experiment. Interleukin-2 concentrations, pooled over all sampling days, were decreased (P less than 0.03) in pseudorabies virus-infected pigs. Viral excretion was not altered by isoprinosine treatment. These data suggest that pseudorabies virus infection decreased lymphocyte proliferative responses and interleukin-2 prodcution in pigs, and that isoprinosine did not mitigate these effects.

Lipopolysaccharide (LPS) fractions were obtained from smooth cultures of Brucella abortus strains 2308 and S-19 by butanol extraction procedures. The LPS from the initial butanol extraction contained 10 to 15% protein and was reduced to less than 1% protein by treatment with proteinase K. The LPS fractions were identified and characterized on the basis of the chemical analysis, sodium dodecyl sulfate gel electrophoresis, cesium chloride gradients, electron microscopy, and gel immunodiffusion. Results indicated that the butanol procedure is a reliable method in the extraction of LPS from Brucella abortus cells. Proteinase K-treated LPS containing less than 1% protein from strain 2308 was used to vaccinate BALB/cByJ mice. Immune and protective criteria for vaccinated and nonvaccinated mice were increased immunoglobulin (IgG and IgM) titers in sera of prechallenge-exposed mice, reduced colony-forming units/spleen, and splenomegaly in post-challenge-exposed mice. Results indicated that proteinase K-treated LPS was immunuogenic as well as protective for mice.

Monoclonal antibodies (MAB) to porcine immunoglobulins were produced by fusion of SP2/0 cells with splenic lymphocytes of mice that had been immunized with porcine IgG or IgA. Of 16 MAB selected for detailed study, 13 reacted with heavy chains (7 anti-gamma, 6 anti-alpha) and 3 reacted with light chains of native immunoglobulin. Several of the same MAB (3 anti-gamma chain, 1 anti-alpha chain, 3 anti-light chain) also reacted with denatured immunoglobulin by use of immunoblotting analysis. Collective results of competitive ELISA, immunodiffusion, and immunoblotting analysis indicated that the 7 MAB of anti-gamma chain specificity were directed to 3 epitopes, the 6 MAB of anti-alpha chain specificity were directed to at least 2 epitopes, and the 3 MAB of anti-light chain specificity were directed to at least 2 epitopes that may have been located on different types of light chains. When tested by immunodiffusion with 5% polyethylene glycol incorporated in the agar matrix, all anti-gamma chain and antilight chain MAB, but no anti-alpha chain MAB, had precipitating activity. When polyethylene glycol was not used, only 4 MAB (all of the anti-gamma chain specificity and of IgM isotype) had precipitating activity. These MAB, with specificity for gamma and alpha chains and those reported earlier with mu-chain specificity, should be invaluable in the detection and quantification of porcine immunoglobulin isotypes. These MAB have potential applications in delineating the porcine immune response to selected immunogens.

Influence of supplemental Se on humoral immune response was measured in 60 weaned beef calves with marginal blood Se status. Calves were fed a Se-deficient diet consisting of corn silage, corn grain, and soybean meal. Blood Se concentrations, primary and secondary humoral immune responses to hen egg lysozyme inoculation, and weight gain were determined in a 70-day trial. Calves fed 20 mg of Se/kg of mineral mixture ad libitum had lower antibody responses (P less than 0.02), compared with calves fed 20 mg of Se/kg of mineral mixture and given 0.1 mg of Se and 0.22 IU of vitamin E/kg of body weight, IM, or with calves fed 80, 120, 160, or 200 mg of Se/kg of mineral mixture. Calves fed 80, 120, 160, or 200 mg of Se/kg of mineral mixture had higher (P less than 0.001) blood Se concentrations on day 70, compared with calves fed 20 mg of Se/kg of mineral mixture and given 0.1 mg of Se and 0.22 IU of vitamin E/kg of body weight, IM. Selenium supplementation had no effect on weight gain.

The effect of aspirin on bovine platelet function and thromboxane A2 (TXA2) production in stimulated platelets was evaluated. A single dose of aspirin (100 mg/kg of body weight) was administered orally to Holstein cows, and blood samples were obtained before and at regular intervals for 7 days after treatment. The production of TXA2 was assessed by measuring the stable metabolite thromboxane B2, using a specific radioimmunoassay. Within 4 hours of aspirin administration, the production of TXA2 was significantly (P less than 0.05) decreased, irrespective of whether collagen, adenosine diphosphate, or platelet activating factor was used to initiate platelet aggregation. Despite the inhibition of TXA2 release from the stimulated platelets, platelet function, assessed by initial rate of aggregate formation and extent of aggregation, was unaffected by aspirin administration. The extent of aggregate formation in response to collagen, adenosine diphosphate, or platelet activating factor was independent of the amount of TXA2 released from platelets before and after aspirin treatment. The results suggested that TXA2 formation is not the primary biochemical pathway involved in the aggregation of stimulated bovine platelets.

The uptake of colostral IgG and IgM, their serum half-lives, and the rates of endogenous synthesis of IgG and IgM were evaluated in 6 newborn foals fed bovine colostrum (principals) and 6 foals allowed to suckle their dams (controls). The principal foals were fed 400 ml of bovine colostrum (IgG, 10,000 mg/dl and IgM, 200 mg/dl) at 2-hour intervals, from 2 to 20 hours after foaling (total dose, 4 L). Serum IgG and IgM concentrations were determined by single radial immunodiffusion from birth to 98 days of age. At foaling, principal foals had no detectable serum equine IgG, but 1 control foal had serum equine IgG of 185 mg/dl. AFter ingestion of colostrum, there was no significant difference in the maximal serum bovine IgG concentration (range, 1,350 to 3,300 mg/dl) in the principal foals, and maximal serum equine IgG concentration (range, 500 to 6,000 mg/dl). The calculated biological bovine and equine IgG half-life in the principal and control groups was 9.4 and 26 days, respectively. Endogenous IgG synthesis was first detected in 1 principal foal at 3 days of age, but was detected first between 28 and 42 days in the other principal foals. Starting on day 56 there was no significant difference in serum equine IgG concentration between groups. At foaling, foals in both groups had low equine IgM concentrations. In the control foals, there was marked individual variation in the increases in equine IgM concentration (range, 5 to 73 mg/dl) after ingestion of colostrum. With the exception of day 49 after foaling, there was no statistical difference between groups for serum IgM concentration after day 3, and both groups had parallel rates of IgM synthesis. Bovine IgM was undetectable at foaling and maximal serum concentration ranged from 200 to 350 mg/dl following ingestion of colostrum. The calculated bovine and equine IgM half-lives were 8 and 5 days, respectively. The coefficients of absorption of bovine IgG and IgM were 30.9 and 84, respectively, in the principal foals. In the control foals, the coefficient of absorption of equine IgG and IgM was 35 and 30, respectively. One principal foal was excluded from the study because it died of aspiration pneumonia at 2 days of age.

Eighteen strains of Escherichia coli serogroup O115:K"V165" isolated from 1- to 8-week-old pigs with diarrhea were tested for toxigenicity, pathogenicity in pigs and mice, serum resistance, mannose-resistant hemagglutination (MRHA), F165 and other surface antigens, colicin V (Col V), aerobactin, and biotype. Twelve strains were positive for heat-stable enterotoxin (STb), MRHA-negative, and F165-negative; 5 strains were enterotoxin-negative, MRHA-positive, and F165-positive; and 1 strain was MRHA-positive, but F165- and enterotoxin-negative. Six of the 12 STb-positive strains moderately colonized the ileum of newborn colostrum-deprived pigs within 24 hours after inoculation. Two of the colonizing strains were able to induce watery diarrhea. All 12 STb-positive strains were nonpathogenic for adult mice and were serum-sensitive; 11 of 12 were Col V-negative, 9 of 12 did not produce aerobactin, and 10 of 12 belonged to biotypes other than 1 or 2. All 6 enterotoxin-negative strains colonized the small and large intestines, associated with peritoneal serosal surfaces, and induced septicemia and polyserositis in newborn colostrum-deprived pigs 1 to 2 days after inoculation. In contrast, 3 STb-positive strains poorly colonized the intestines and did not induce septicemia in pigs at 3 days after inoculation. All 6 enterotoxin-negative strains were Col V-positive, produced aerobactin, and belonged to biotype 1 or 2. Of the 5 enterotoxin-negative, F165-positive strains, only 4 were pathogenic for intraperitoneally inoculated adult mice and were serum-resistant. The enterotoxin-negative, F165-negative strain was neither serum-resistant nor mouse-pathogenic. O-agglutinable mutants of the mouse-pathogenic strains were, for the most part, no longer pathogenic for adult mice, although these strains remained unchanged for biotype and production of MRHA, F165, and Col V, and 3 of 4 mutant strains were serum-resistant. Thus, E coli strains of the same serogroup isolated from diarrheic pigs may cause either intestinal or extraintestinal disease upon reinoculation of pigs, depending on the virulence attributes produced by the strains.

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.

The ability of pseudorabies virus (PRV) to infect and establish latency in pigs with passively acquired (maternal) antibody for PRV was tested by exposing such pigs to the virus and subsequently attempting to reactivate latent virus by administering large doses of dexamethasone. Pigs of each of 4 litters that had nursed gilts with relatively high (512, gilts 1 and 2), moderate (32, gilt 3), and no (less than 2, gilt 4) serum titers of virus-neutralizing (VN) antibodies for PRV were allotted to 3 treatment groups (A, B, C) when they were 2 weeks old. Group-A pigs were separated from littermates and dam and thereafter kept in isolation; group-B pigs were experimentally exposed oronasally to PRV and 1 hour later returned to their dam; group-C pigs were kept with their dam and potentially exposed to PRV by contact with littermates of group B. Sera obtained from pigs at selected intervals until they were 17 weeks old were tested for VN activity and for precipitating activity for radiolabeled viral proteins. All group-A pigs remained clinically normal throughout the experiment. Depending on the initial amount of passively acquired antibody, little or no serum VN or precipitating activity remained by the time these pigs were 17 weeks old. Group-B and -C pigs, with relatively high amounts of passively acquired antibody when exposed to PRV, also remained clinically normal. However, most became latently infected as subsequently evidenced by either dexamethasone-induced or noninduced virus reactivation. Noninduced reactivation may have been initiated by weaning the pigs when they were about 8 weeks old. Group-B and -C pigs with no or moderate amounts of passively acquired antibody when exposed to PRV, had severe clinical signs. These pigs either died or recovered but remained stunted in growth. Virus was reactivated in all of the recovered pigs by treatment with dexamethasone. Quantitative and qualitative changes in serum precipitating activity, especially for viral proteins of relatively low molecular weight (less than 46,000), were a more consistent indication of virus reactivation than were either increased VN titers or virus isolation. Results with litters 1 and 2 clearly indicate that latent infection of young pigs with highly virulent PRV can develop in the absence of clinical signs.