We investigated the ability of an antibody-specific, O antigen-based ELISA to document Salmonella typhimurium herd infections by screening of milk samples. Three cattle populations, 20 herds with no history of salmonellosis, 8 herds with history of S. typhimurium episodes within the previous 7 months, and 220 herds of unknown disease status, were tested. A herd was considered ELISA positive if at least 5% of the cows had OD values > 0.3. Among the 20 herds without history of salmonellosis, only 2 herds were ELISA positive, whereas all 8 herds with a known history of salmonellosis were ELISA positive (herd specificity, 0.9 and herd sensitivity, 1.0). A significant correlation (P < 0.001) was found between the OD values of serum and milk samples from cows in the herds with a history of salmonellosis. It was concluded that ELISA testing of individual milk samples can be used for surveillance of herds for S. typhimurium infections, but further modifications are needed to test bulk tank milk samples.

Cows and calves from a 1,600-cow drylot dairy were screened for IgG antibodies to Salmonella dublin lipopolysaccharide (LPS), using an indirect ELISA. The ELISA was performed on milk samples from lactating cows and on sera from nonlactating cows and calves. Fecal samples were collected from calves and nonlactating cows for culture of Salmonella spp. All seropositive cattle were retested by culture and ELISA 5 times at monthly intervals or until antibody concentration decreased. None of the cattle remained culture-positive and seronegative. Prior to and during the sample collection period, approximately 30% of calves < 8 weeks old died of S dublin infection. Vaccination of cows with a killed S dublin/S typhimurium vaccine at cessation of lactation was a routine management practice. The ELISA-determined Igg response to vaccination had decreased by 50 days after vaccination. Eight cows and 5 calves that maintained a high serologic response to S dublin were purchased and moved to a research facility for 6 months of intensive monitoring. Lactating cows were milked twice daily, and culture of milk and feces for Salmonella spp was performed 5 times/wk. Serum IgG antibodies to S dublin LPS were measured weekly, using ELISA. At the end of 6 months, all 13 cattle were necropsied and tissues were obtained for culture of Salmonella spp. All 8 cows and 5 calves maintained persistently high ELISA titer for the 6 months of testing, and shed S dublin in the milk and/or feces during the same period. On this basis, they were termed S dublin carriers. Salmonella dublin was isolated from mammary tissue of 2 calves at necropsy, indicating that bacteremia may be a mode of mammary infection by S dublin. Results of the study indicated serologic testing can be used successfully on a large dairy to identify S dublin carrier cattle. Using initial milk screening, 42 of 1,268 lactating cows were identified as suspect, requiring repeated serologic testing. One nonlactating cow, 7 of the 42 suspect lactating cows, and 5 of the 222 calves maintained an Igg response, and were found to be S dublin carriers. Carrier cows shed S dublin in 3.35% of fecal samples and 2.51% of milk samples, and carrier calves shed S dublin in 17.26% of fecal samples.

Saline (0.9% NaCl) solution or 1 of 3 nonsteroidal anti-inflammatory drugs (NSAID) was administered IV to 5 neonatal calves 15 minutes after the start of a 3-hour IV infusion of Escherichia coli lipopolysaccharide (LPS; 2 micrograms/kg/h). Four additional calves were given a 3-hour IV infusion of saline solution alone. Clinical attitude, mean arterial blood pressure, PCV, WBC, and plasma lactate, glucose, and eicosanoid concentrations (thromboxane B2, 6-keto-PGF(1 alpha)) were monitored for 12 hours. Flunixin meglumine (1.1 mg/kg of body weight, IV), ketoprofen (2.2 mg/kg, IV), and ketorolac tromethamine (1.1 mg/kg, IV) each ameliorated the clinical signs of endotoxemia and LPS-induced lacticemia, but failed to significantly alter the degree of leukopenia or hypoglycemia associated with infusion of LPS. Although the 3 NSAID prevented eicosanoid production, they provided only partial protection against LPS-induced hypotension. Each NSAID modified the response to LPS, but none was clearly superior to the others in modulating the clinical signs or physiologic alterations induced by infusion of LPS in neonatal calves.

The antibiotic polymyxin B sulfate is a cationic polypeptide with a unique cyclical configuration and distinct cationic characteristics. In this investigation, polymyxin B was evaluated to determine its ability to prevent synthesis of lactic acid and tumor necrosis factor-alpha (TNF-alpha) by lipopolysaccharide-stimulated strain RAW 2647 macrophage-like cell populations. In this context, gradient concentrations of polymyxin B were formulated in the presence of fixed concentrations of lipopolysaccharide fractions from Escherichia coli (B4:0111), E. coli (J5), Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella minnesota, and S. typhimurium (Re). Quantitation of TNF-alpha was established by the application of a tissue culture-based biological assay system, using the WEHI 164 clone 13 indicator cell line. Investigations also included evaluation of the ability of gradient concentrations of lipopolysaccharide fractions from E. coli (B4:0111), E. coli (J5), K. pneumoniae, P. aeruginosa, S. minnesota, and S. typhimurium (Re) to form a complex with polymyxin B. This was established through application of high-performance thin-layer chromatography techniques. On the basis of the known molecular characteristics of lipopolysaccharide, its lipid A-core subfractions, and polymyxin B, these results imply that cytoprotective properties of polymyxin B are attributable to direct interaction and subsequent complex formation. More specifically, the mechanism by which polymyxin B exerts affinity for lipopolysaccharide fractions is proposed to occur through attractive ionic interactions established between the cationic diaminobutyric acid residues of polymyxin B and the mono- or diphosphate group(s) of the lipid A-core moiety. It is highly probable that this molecular phenomenon is accompanied by hydrophobic interactions established between the terminal methyloctanoyl or methylheptanoyl groups of polymyxin B and the saturated carbon chains of the lipid A-core subfraction of lipopolysaccharide fractions.

The role of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor a during endotoxin-induced mastitis in cows was characterized. Six cows had 10 microgram of Escherichia coli lipopolysaccharide infused into 1 mammary gland. Three other cows served as nontreated controls. Within 1.5 to 2.5 hours after infusion, endotoxin caused obvious edema of the mammary gland and increased serum albumin concentration in milk of infused glands 6 times. Milk somatic cell count began to increase 3 to 5 hours after infusion in all treated glands. At 7 hours after infusion, somatic cell counts were increased > 10 times, compared with counts in milk from control cows. Pyrexia of > 1 C developed in only 1 cow, but all treated cows had serum cortisol concentrations > 50 ng/ml in response to endotoxin treatment. High concentrations of IL-1 (10 to 600 U/ml) and IL-6 (2 to 22 U/ml) were detected in milk of infused glands beginning 2.5 to 4 hours after infusion. Endotoxin did not induce detectable amounts of tumor necrosis factor activity in milk or serum. Swelling and mammary gland permeability changes preceded any detectable increase in IL-1 and IL-6 activity, indicating that these clinical signs of inflammation were not mediated by these cytokines. Systemic responses and the leukocytic influx into endotoxin-infused glands developed after or concurrently with initial increases in IL-1 and IL-6 activities in milk. These results suggested that IL-1 and IL-6 may have a role in mammary gland defenses and in the pathophysiologic changes during endotoxin-induced mastitis.

Age, species, and disease state may substantially alter the disposition and clearance of pharmacologic agents. This is particularly important when drugs with low therapeutic index are used in ill neonates. Pharmacokinetic variables for phenylbutazone were determined in 24- to 32-hour-old healthy and endotoxemic calves after IV administration of a single dose (5 mg/kg of body weight, IV). Elimination halflife was 207 and 168 hours, and clearance was 0.708 and 0.828 ml/kg/h in healthy and endotoxemic calves, respectively. Intravenous infusion of endotoxin at the dose (2 micrograms/kg over 4 hours) given did not significantly alter any of the calculated pharmacokinetic variables. Serum thromboxane B2 concentration was significantly (P = 0.05) suppressed for 3 hours after phenylbutazone administration in healthy calves and for 4 hours in endotoxin-challenged calves. Daily administration of phenylbutazone (10 mg/kg loading, then 5 mg/kg for 9 days) to healthy and endotoxemic calves failed to induce any lesions consistent with nonsteroidal anti-inflammatory drug toxicosis.

We examined the effect of infusion of lipopolysaccharide (LPS) on serum tumor necrosis factor alpha (TNF alpha) concentration and clinical attitude in 2- to 3-day-old colostrum-fed (CF) and colostrum-deprived (CD) foals. Eleven CF and 8 CD neonatal foals were given a bolus IV infusion of Escherichia coli 055:B5 lipopolysaccharide (0.5 microgram/kg of body weight) in sterile saline (0.9% NaCl) solution. Four CF and 2 CD foals were given saline solution alone. Serum IgG concentration and serum anti-LPS IGG(T) antibody titer were determined for each foal prior to infusion. A depression index was used to score clinical abnormalities. Serum TNF alpha concentration was estimated by use of an in vitro cytotoxicity bioassay that used WEHI 164 clone 13 cells as targets. The cytotoxic serum factor was identified as TNF alpha by immunoprecipitation with caprine antisera raised against the 15 NH2-terminal amino acids of human TNF alpha. Tumor necrosis factor alpha was not detected in any preinfusion serum samples nor in any samples from foals given saline solution alone. Serum TNF alpha concentration increased in all LPS-infused foals and peaked between 60 and 90 minutes after infusion. Serum TNF alpha concentrations, expressed as mean percentage of peak serum TNF alpha concentration, persisted longer in CD foals given LPS than in CF foals given LPS. All LPS-infused foals displayed clinical signs of endotoxemia, but mean depression index scores of the CF and CD foals given LPS were not significantly different at any time. Serum TNF alpha concentrations were correlated with depression index scores in both LPS-infused groups. Mean rectal temperature increased by 1 hour and remained high for 4 hours after infusion in CF foals given LPS. Mean rectal temperature in CD foals given LPS was significantly less than that for CF foals given LPS 1 and 2 hours after infusion and was higher than mean rectal temperature prior to infusion 3 and 4 hours after infusion. Neither preinfusion total serum IgG concentration nor serum anti-LPS IgG(T) antibody titer correlated with peak serum TNF alpha concentration in the 19 LPS-infused foals.

The cellular response induced in the host animal by endotoxin contributes greatly to the morbidity and mortality of gram-negative infections in bovine neonates. We characterized the temporal sequence, magnitude, and duration of mediator release during endotoxemia and evaluated the effect of endotoxin dose and method of administration. Thromboxane B2 (TxB2), and 6-keto prostaglandin F(1 alpha) (PGF 1 alpha) concentrations and tumor necrosis factor (TNF), and interleukin-1 beta (IL-1 beta) activities were measured in 34 newborn calves given Escherichia coli endotoxin at dosage of 0 (saline solution), 0.2, 2.0, or 20 micrograms/kg of body weight, either by IV administered bolus or infusion over 50 minutes. In all groups and at each lipopolysaccharide dosage, mediators peaked in this sequence; TxB2 and TNF, followed by PGF 1 alpha, then IL-1 beta. Neither dose nor method of administration affected the sequence of mediator release. The magnitude of eicosanoid response to endotoxin was dose-dependent. During induced endotoxemia, duration and/or magnitude of mediator response reflected the dose of endotoxin administered, indicating that the outcome of endotoxemia, in neonatal calves, may be related to the amount of circulating endotoxin.

A commercially available Salmonella bacterin was administered to Holstein calves starting at 1 to 19 weeks of age. Serum samples were obtained before administering bacterin and at 2-week intervals thereafter. An ELISA with Salmonella dublin lipopolysaccharide (LPS) or S dublin whole cells as antigen, was used to measure specific IgG and IgM responses. Antibody responses to LPS were not detected from calves < 12 weeks old inoculated with killed bacterin. Immunoglobulin responses to whole-cell antigen were detected from all age groups of calves inoculated with the same killed Salmonella bacterin. Calves < 11 weeks old are able to produce immunoglobulins to some whole-cell antigens, but are unable to produce anti-LPS immunoglobulins when inoculated with killed Salmonella bacterin. This age-related response to killed Salmonella antigens may account, in part, for increased susceptibility to salmonellosis in calves < 12 weeks old. In comparison to the response for killed antigen, 8 calves given modified-live aromatic-dependent S dublin bacterin at 1 to 3 weeks of age had detectable anti-LPS immunoglobulin after immunization, although the response was not as rapid and was of a lesser magnitude than that of older calves given killed Salmonella bacterin.

In an attempt to establish if cross protection can be induced by different strains of Haemophilus parasuis, three groups of 12 gnotobiotic pigs were immunized each with an aluminum hydroxide adsorbed whole cell bacterin of one of three H. parasuis strains. Two weeks later, four pigs within each vaccinated group were challenged with aerosols of live cultures of each of the three test strains and observed for response. Two virulent strains V1 and V2 protected all the vaccinated pigs, while all non-vaccinated controls succumbed to Glasser's disease when challenged with these strains. Vaccination with strain LV (of low virulence) protected the pigs against challenge with strain V2, but not against strain V1. Strain LV did not cause disease in the immunized animals and only in one of ten nonimmunized pigs upon second challenge. The results suggest that strains may differ in antigenicity and that virulence and immunoprotection are positively related. Strains to be used in commercial vaccines should therefore be selected carefully. Antibodies detected in the sera of vaccinated pigs were to outer membrane proteins of the bacteria, but not to lipopolysaccharides or capsular polysaccharides. This would suggest that for gnotobiotic pigs outer membrane proteins are more immunogenic than lipopolysaccharide or capsular antigens. Further work is needed to determine if outer membrane proteins also contribute protective immunogens.