Interferon-alpha and haptoglobin in pigs selectively bred for high and low immune response and infected with Mycoplasma hyorhinis

Evaluation of colonization, variable lipoprotein-based serological response, and cellular immune response of Mycoplasma hyorhinis in experimentally infected swine

Mycoplasma hyorhinis (Mhr) is a commensal of the upper respiratory tract that can be shed by nasal secretions and transmitted by direct contact in neonatal and nursery pigs. Lesions associated with Mhr infection include polyserositis and arthritis; however, systemic Mhr disease pathogenesis is not well characterized. This study aimed to investigate the immunopathogenesis and bacterial dissemination pattern of Mhr using single and multiple inoculation approaches in a caesarian-derived colostrum-deprived (CDCD) pig model. Animals in three treatment groups were inoculated once (Mhr 1; n = 12) or four (Mhr 2; n = 8) times with Mhr or sham-inoculated (NC group; n = 3) nasally and by tonsillar painting. Inoculum consisted of a triple cloned Mhr field isolate (4.5 × 10⁷ CFU/mL) in Friis medium. Clinical signs were evaluated daily during the study. Serum and oral fluid antibody (IgA and IgG) response and cellular immune response were assessed using a recombinant chimeric VlpA-G-based indirect ELISA and by ELISpot, respectively. The presence of Mhr in oral fluids, nasal and oropharyngeal swabs were evaluated by qPCR. At 6 wpi, pigs were euthanized and evaluated for gross lesions consistent with Mhr and bacterial colonization in tonsils by qPCR. No clinical signs or gross lesions consistent with Mhr-associated disease were observed throughout the study. For Mhr 2 group, the presence of IgA and IgG in serum and oral fluids were detected at 2 and 4 weeks post-inoculation (wpi), respectively, while in Mhr 1, only IgA was detected in oral fluids at 6 wpi. The proportion of animals shedding Mhr in nasal secretions varied from 20 to 40 % in the Mhr 1 and 62.5-100% in the Mhr 2 group. However, the proportion of animals shedding Mhr in oropharyngeal swabs was consistent through the study (60 %) in Mhr 1 and fluctuated from 20 % to 87.5 % in Mhr 2 group. The lack of clinical signs and the presence of Mhr specific humoral response and bacterial colonization indicates that the multiple inoculation experimental model may mimic subclinical natural infection in the field. In addition, the humoral and transient cellular response did not result in bacterial clearance. Based on these results, animals would have to be exposed multiple times to mount a detectable immune response.

Acute phase protein pattern and antibody response in pigs experimentally infected with a moderate dose of Trichinella spiralis, T. britovi, and T. pseudospiralis

The aim of the present study was to evaluate the acute-phase protein (APP) response in three groups of pigs experimentally infected with a moderate infective dose, i.e. 1000 muscle larvae (ML) of Trichinella spiralis, 3000 ML of Trichinella britovi, and 2000 ML of Trichinella pseudospiralis. Over a 62-day period of infection, we examined the serum level and kinetics of the haptoglobin (Hp), C-reactive protein (CRP), serum amyloid A (SAA), and pig major acute-phase protein (pig-MAP). In addition, to better understand the immune response of pigs experimentally infected with three different species of Trichinella, the kinetics of IgG and IgM antibodies against excretory-secretory (ES) antigens of Trichinella ML were also investigated. In order to assess anti-Trichinella IgG dynamics, we used a commercial and an in-house ELISA based on both heterologous (T. spiralis) and homologous (T. spiralis, T. britovi, and T. pseudospiralis) Trichinella species ES antigens. Among the four APPs analyzed, the concentration of CRP and pig-MAP significantly increased only in T. britovi-infected swine when compared with control pigs. This took place as early as 6 days post-infection (dpi). Hp was the only APP whose concentration significantly increased in pigs infected with T. pseudospiralis, this occurring as late as on day 62 pi. Despite the statistical differences found, increases in pig-MAP, CRP, and Hp levels were rather mild and transitory; none of these proteins were found to be elevated in the serum of all experimental groups of pigs at the same time point after infection. Specific IgG antibodies against ES antigens of Trichinella ML were first detected by the commercial and in-house T. spiralis ML ES-antigen ELISAs on days 30, 36 and 36 pi in pigs experimentally infected with T. spiralis, T. britovi, and T. pseudospiralis, respectively. However, seroconversion in pigs experimentally infected with T. britovi was detected slightly earlier (30 dpi) when the ELISA based on homologous rather than heterologous ES antigens was applied. In serum samples from pigs infected with T. spiralis, statistically significant increases in the level of specific IgM antibodies against T. spiralis ML ES antigens were first detected on day 30 pi and after this time, their concentration began to decrease. No changes in the level of anti-Trichinella IgM were observed in T. britovi- or T. pseudospiralis-infected pigs throughout the entire period of the experiment.

Associations of Blood Analysis with Feed Efficiency and Developmental Stage in Grass-Fed Beef Heifers

Simple Summary

Individual cattle of identical developmental stage vary in their efficiency of feed utilization to achieve a similar productive performance in terms of growth rate and body composition upon accounting for breed, age and gestation stage. Technical issues to measure individual feed intake on the farm limits the identification of feed-efficient cattle. This creates a demand for indirect approaches to infer feed efficiency, such as blood parameters. Our study revealed differences in blood parameters when comparing grass-fed heifers classified as either efficient or inefficient. These differences were also influenced by the developmental stage of the heifers; some blood analytes had distinct relevance to infer about feed efficiency when comparing younger non-pregnant heifers with older and pregnant heifers. In general, improved feed efficiency seems to relate to a lower oxygen carrying capacity. We also provide evidence of associations between indicators of the immune system, blood enzymes and ions and feed efficiency. Additionally, blood analysis presented metabolic differences between non-pregnant heifers with older and pregnant heifers. Blood analysis as a practical measure for feed efficiency has relevance in the nutritional management and genetic improvement of beef cattle, which will contribute to the broad sustainability of beef farming.

Abstract

Proxies for feed efficiency, such as blood-based indicators, applicable across heifers varying in genetic makeup and developmental state are needed. Assessments of blood analytes and performance were made in heifer calves and pregnant heifers. Residual feed intake, a measure of feed efficiency, was used to categorize each population of heifers as either efficient or inefficient. Efficient heifer calves had lower mean cell hemoglobin, greater lymphocyte count, and fewer segmented neutrophils at the end of the test compared to inefficient calves. Efficient pregnant heifers had greater counts of lymphocytes with fewer segmented neutrophils at the end than inefficient pregnant heifers. Efficient heifer calves exhibited higher specific immunoglobulin M than inefficient calves. Throughout the test, efficient heifer calves had elevated potassium and phosphorus, and reduced alkaline phosphatase (ALP) compared to inefficient heifers. Efficient pregnant heifers showed greater ALP, non-esterified fatty acids and creatinine, but lower cholesterol and globulin than inefficient pregnant heifers. Levels of red and white blood cells, creatine kinase, cholesterol, glucose, potassium and phosphorus were higher in heifer calves compared with pregnant heifers. There is potential for blood analytes as proxies for feed efficiency; however, it is necessary to consider the inherent associations with feed efficiency and heifers’ developmental stage.

Health and immune traits of Basque and Large White pigs housed in a conventional or enriched environment

Since decades, production traits such as growth rate, feed efficiency or body composition have been drastically increased in pigs by genetic selection. Whether this selection impacted animal robustness is still unclear. In this study, we compared Large White (LW) pigs, a breed submitted to intense genetic selection for production traits, and Basque (B) pigs, a local rustic breed, reared in two different housing environments (conventional v. enriched). Adaptation to housing conditions among each breed was evaluated at the level of endocrine and immune traits. These are known to be impacted by housing conditions and breed; however, the interaction effects between genotype and environment are less described. Animals (20 per breed and housing environment) entered the experiment at 35 kg of live weight. Levels of cortisol, acute-phase inflammatory proteins, immunoglobulins and hydrogen peroxide, blood formula, lymphocyte proliferation and in-vitro cytokine expression were measured at ∼115 kg of live weight. Animals were checked for skin injuries during the growing period. At slaughter, at the average live weight of 145 kg, carcasses were examined for pathological conditions of the respiratory tract. The major result was that the two breeds exhibited differences in response to the housing environment. Among the 24 sanitary, endocrine or immune traits investigated, the housing conditions affected eight variables in both breeds (salivary cortisol at 0700 and 1900 h, severity of pneumonia at slaughter) or only in B pigs (severe skin lesions) or LW pigs (salivary cortisol at 1500 h, granulocyte numbers and lymphocyte/granulocyte ratio and lymphocyte proliferation). These observations strengthen the hypothesis that selection for high meat production level might be associated with an increased susceptibility of animals to environmental stressors.

Serum acute phase proteins as biomarkers of pleuritis and cranio-ventral pulmonary consolidation in slaughter-aged pigs

The purpose of this study was to investigate the relationship between the existence of lung lesions in pigs at slaughter and the concentration of the serum acute phase proteins (APP), haptoglobin (Hp), pig-major acute protein (Pig-MAP) and C-reactive protein (CRP). A total of 24 pig farms were selected out of a larger farm database previously screened to study risk factors associated with pleuritis and cranio-ventral pulmonary consolidation (CVPC) lesions at slaughter-aged pigs in Spain. The farms were classified as "pleuritis negative (P-) or positive (P+)" and as "CVPC negative (M-) or positive (M+)" and divided into four groups according to a 2X2 factorial design (P-M-, P-M+, P+M-, P+M+). Also at slaughter, blood from 20 randomly selected pigs from each farm was collected. Obtained serum samples were used to measure acute phase proteins. All APP concentrations were significantly higher for M+ farms than for M- ones. However, only Hp and Pig-MAP showed significantly higher concentrations for P+ farms than for P- ones. Pig-MAP was the most sensitive biomarker since it was able to clearly discriminate between P-/P+ and M-/M+ groups (p<0.001 in both cases). Hp was an excellent marker for pleuritis and good for CVPC lesions. CRP was able to discriminate for CVPC lesions but not for pleuritis. The present results indicate that Pig-MAP and, possibly Hp, may be used as potential markers to characterise and discriminate respiratory lesions in swine herds at slaughter.

Acute phase response in porcine reproductive and respiratory syndrome virus infection

This study was focused on the changes observed in the serum concentration of haptoglobin (Hp), C-reactive protein (CRP), serum amyloid A (SAA) and Pig-major acute protein (Pig-MAP), during experimental porcine reproductive and respiratory syndrome virus (PRRSV) infection and in their relationship with the expression of interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α). Hp and Pig-MAP serum levels were increased at 10 dpi, but CRP and SAA showed a delayed and highly variable increase. All three proinflammatory cytokines were poorly expressed, and only a mild increase in IL-1β was observed at 7 dpi. The increased expression of Hp coincided with the light enhancement observed in both IL-6 and TNF-α, and might be related with an increased expression of IL-10. The low expression of TNF-α might point to a possible mechanism of viral evasion of host-immune response. This issue and the delayed expression of CRP and SAA should be taken into account in future studies about modulation of the immune response by PRRSV infection.

Low levels of haptoglobin and putative amino acid sequence in Taiwanese Lanyu miniature pigs

Porcine haptoglobin (Hp) is an acute phase protein. Its plasma level increases significantly during inflammation and infection. One of the main functions of Hp is to bind free hemoglobin (Hb) and inhibit its oxidative activity. In the present report, we studied the Hp phenotype of Taiwanese Lanyu miniature pigs (TLY minipigs; n=43) and found their Hp structure to be a homodimer (beta-alpha-alpha-beta) similar to human Hp 1-1. Interestingly, Western blot and high performance liquid chromatographic (HPLC) analysis showed that 25% of the TLY minipigs possessed low or no plasma Hp level (<0.05 mg/ml). The Hp cDNA of these TLY minipigs was then cloned, and the translated amino acid sequence was analyzed. No sequences were found to be deficient; they showed a 99.7% identity with domestic pigs (NP_999165). The mean overall Hp level of the TLY minipigs (0.21 +/- 0.25 mg/ml; n=43) determined by enzyme-linked immunosorbent assay (ELISA) was markedly lower than that of domestic pigs (0.78 +/- 0.45 mg/ml; p<0.001), while 25% of the TLY minipigs had an Hp level that was extremely low (<0.05 mg/ml). In addition, the initial recovery rate (first 40 min) in the circulation of infused fluorescein isothiocyanate (FITC)-Hb was significantly higher in the TLY minipigs with extremely low Hp levels than those with high levels. This data suggests that the low concentration of Hp-Hb complex is responsible for the higher recovery rate of Hb in the circulation. TLY minipigs have been used as an experimental model for cardiovascular diseases; whether they can be used as a model for inflammatory diseases, with Hp as a marker, remains a topic of interest. However, since the Hp level varies significantly among individual TLY minipigs, it is necessary to prescreen the Hp levels of the animals to minimize variation in the experimental baseline. The present study may provide a reference value for future use of the TLY minipig as an animal model for inflammation-associated diseases.

A role for immunology in invasion biology

Invasive species are of increasing conservation and economic concern, yet mechanisms underlying invasions remain poorly understood. We propose that variation in immune defences might help explain why only some introduced populations become invasive. Introduced species escape many of their native diseases, but also face novel pathogens that can induce costly, and sometimes deadly, immune responses in naïve hosts. Therefore, favouring less resource-demanding and dangerous defence mechanisms and allocating a greater proportion of resources to growth and reproduction should favour invasion. Specifically, we argue that successful invaders should reduce costly systemic inflammatory responses, which are associated with fever and metabolic and behavioural changes, and rely more heavily on less expensive antibody-mediated immunity. Here we provide supporting arguments for this hypothesis and generate predictions that are testable using tools from the growing field of ecological immunology.

Influence of rearing conditions and respiratory disease on haptoglobin levels in the pig at slaughter

Associations between serum concentrations of haptoglobin, pathological lung lesions indicative of Mycoplasma hyopneumoniae (EP) or Actinobacillus pleuropneumoniae (PL) infection at slaughter and previous rearing environment were investigated in 510 pigs (90-100 kg live weight) from 17 farms in England. Haptoglobin concentrations were significantly higher in pigs showing pathological signs of EP infection compared to those without signs of this disease (EP positive median 0.43 mg ml(-1) vs. EP negative median 0.26 mg ml(-1), p<0.01). However, there were no significant associations between serum haptoglobin concentrations and pathological signs of PL. The presence of solid partitions compared with barred or similar open partitions was associated with a decrease of 0.44 mg ml(-1) farm mean haptoglobin concentration, whilst an increase in pen size of 10 m(2) was associated with a decrease of 0.08 mg ml(-1) farm mean haptoglobin concentration. The findings indicate that pathological signs of EP were associated with increased serum haptoglobin at slaughter, which in turn was influenced by components of the farm environment.

Associations of acute phase protein levels with growth performance and with selection for growth performance in Large White pigs

Abstract Acute phase proteins (APP) are released into the circulation in mammals upon infection and may be used to diagnose the health status of managed populations of animals such as pigs. The current study determines APP levels in a population of apparently healthy Large White pigs from a single farm, to address two questions: (1) whether phenotypic associations can be observed between productivity and APP, indicating the effects of possible subclinical infections and (2) whether previous selection for either food intake or ‘lean growth under restricted feeding’ influences APP levels. The APP investigated were alpha1- acid glycoprotein (AGP) and haptoglobin. The APP were measured at 18 and 24 weeks of age in pigs previously selected for high lean growth (no. = 31), low lean growth (no. = 38), high daily food intake (no. = 24) and low daily food intake (no. = 26), but performing under ad libitum feeding conditions. Performance traits and APP levels were constant over the experimental period, indicating that the farm health status did not vary over time. Performance traits and APP were recorded on 119 pigs, of which 80 had both APP and performance measurements. Multiple regression analyses were used to investigate phenotypic relationships between performance traits and APP levels. Plasma concentrations of AGP were higher in 18-week-old pigs compared with 24-week-old pigs (P< 0·01) whereas haptoglobin levels did not vary according to age. Significant sex differences in APP levels were observed. Females had higher circulating levels of AGP than males at both 18 weeks and 24 weeks. Females also had higher levels of haptoglobin at 18 weeks. Levels of AGP had significant negative correlations with daily weight gain (−0·59,P< 0·01 and −0·48,P< 0·05 at 18 and 24 weeks respectively) and with daily food intake (−0·53,P< 0·01 and −0·38,P< 0·05 at 18 and 24 weeks respectively). At age 24 weeks, haptoglobin was negatively correlated with both daily weight gain (−0·35,P< 0·05) and food efficiency (−0·34,P< 0·05). Pigs selected for high lean growth under restricted feeding had higher AGP levels than pigs selected for low lean growth under restricted feeding at 18 (593v. 332 μg/ml,P< 0·01) and 24 weeks of age (313 v. 219 μg/ml,P< 0·05). Selection for daily food intake did not consistently affect AGP levels, and neither selection criteria influenced plasma haptoglobin concentrations. To conclude, we have demonstrated that amongst contemporaneous pigs of the same genotype, higher systemic AGP levels and, to a lesser extent, higher haptoglobin levels are associated with decreased performance, and that genetic selection for ‘efficient lean growth under restricted feeding’ can increase serum AGP levels.

Porcine Acute Phase Protein Concentrations in Different Diseases in Field Conditions

Five acute phase proteins (APPs) [C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (Hp), pig-MAP and albumin] were measured in pigs with naturally occurring infections by porcine reproductive and respiratory syndrome virus (PRRSV), Aujeszky's disease virus (ADV), porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae, and in animals with tail and ear bites, arthritis and other acute inflammatory processes. Healthy specific pathogen-free (SPF) pigs were used as controls. In PRRSV-infected pigs, all APPs with the exception of pig-MAP exhibited significant changes compared with controls. In animals affected with ADV only Hp presented changes of statistical significance, whereas pigs with PCV2 showed marked modifications in all APPs tested. Animals affected with Mycoplasmosis showed concentrations of all positive APPs significantly above levels obtained in SPF pigs, though albumin concentrations did not differ from controls. Finally, all APPs studied showed substantial changes in pigs with acute inflammation. The results indicated that an acute phase response was developed in the different diseases studied, this response being higher in animals with clinical signs and concurrent bacterial processes. Haptoglobin would be the APP that better reflects pathological states; however, to get more complete and valuable information it might be advisable to perform APPs profiles including another APP, such as CRP or SAA.

The porcine acute phase protein response to acute clinical and subclinical experimental infection with Streptococcus suis

The pig acute phase protein (APP) response to experimental Streptococcus suis (S. suis) infection was mapped by the measurement of the positive APPs C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (Hp) and major acute phase protein (pig-MAP) and the negative APPs albumin and apolipoprotein (Apo) A-I. The aim was to elucidate the differences in the acute phase behaviour of the individual APPs during a typical bacterial septicaemic infection. Pigs were inoculated subcutaneously with live S. suis serotype 2 and blood was sampled before and on various days post inoculation (p.i.), until the pigs were killed and autopsied on day 14 p.i. Clinical signs (fever and lameness) were observed in four of the five inoculated pigs from day 2 p.i., and these pigs also had arthritic lesions at autopsy. CRP and SAA showed fast increases in serum concentrations, CRP being elevated from days 1 to 12 p.i. and peaking at 10 times the day 0-levels on day 1 p.i. SAA rose quickly to peak levels of 30-40 times the day 0-level on days 1-2 and returned to pre-inoculation level on day 5 p.i. Hp and pig-MAP showed slightly slower responses, both peaking around 5 days p.i. Hp was increased throughout the experiment with maximum levels around 10 times the day 0-levels, and pig-MAP was elevated on days 1-12 p.i. with peak levels of around seven times the day 0-levels. Apo A-I was decreased from days 1 to 8 and showed minimum levels of about 40% of day 0-levels around 1-2 days p.i. No clear pattern of changes in albumin levels could be identified. One pig, showing clinical signs on day 2 only, also showed an APP response, although of a relatively short duration, whereas three pigs presenting clinical signs for several days had a more protracted acute phase response. Remarkably, the one pig showing no clinical signs and no arthritic lesions showed an APP response comparable to that of the other, clinically affected pigs. Thus, both acute clinical and subclinical S. suis infection could be revealed by the measurement of one or more of the APPs CRP, SAA, Hp, pig-MAP and Apo A-I. The combined measurement of two or three APPs, including proteins with slow and fast kinetics, should be used to achieve the highest sensitivity for the detection of ongoing S. suis infection during a prolonged time period. A diagnostic tool based on such APP-measurements could considerably improve strategic control procedures for this important infection.

Innate immune traits differ between Meishan and Large White pigs

A panel of innate immune traits were compared between Meishan and Large White pigs. These pigs were of similar age and kept under the same environmental conditions to reduce non-genetically derived variation in immune traits. The animals were all apparently healthy and were not experimentally challenged with any pathogen during the study. The measures only required a small blood sample. Total white cell counts were similar between the pig breeds. However, the numbers of lymphocytes, neutrophils and monocytes differed significantly, with Meishans having higher neutrophil and monocyte counts and lower lymphocyte counts. Flow cytometric methods were used to determine quantitatively the characteristics and function of neutrophils and monocytes. Meishan neutrophils were smaller and less complex than Large White neutrophils, and phagocytosis of Escherichia coli and the ensuing oxidative burst was lower in Meishan neutrophils compared to Large White neutrophils. Monocyte phagocytosis of E. coli was significantly less than that of neutrophils in both breeds but the function of Meishan monocytes as measured by phagocytosis and tumour necrosis factor alpha (TNFalpha) release did not differ from that of Large White monocytes. Levels of acute phase proteins also differed between the breeds with a significantly higher proportion of Meishans having elevated serum amyloid A levels. However, Meishans had lower alpha(1)-acid glycoprotein levels than Large Whites and haptoglobin levels were similar. Such differences in innate immune traits may have implications in the resistance to infection by a broad range of pathogens and subsequent disease effects in these breeds. Further studies are warranted to investigate the genes underlying these traits.

Tumor necrosis factor-, interleukin-6, serum amyloid A, haptoglobin, and cortisol concentrations in sows following intramammary inoculation of Escherichia coli

OBJECTIVE

To determine whether concentrations of proinflammatory cytokines, acute-phase proteins, and cortisol differ at parturition among 3 categories of sows (noninoculated, clinically affected and nonaffected following intramammary inoculation with Escherichia coll).

ANIMALS

16 sows.

PROCEDURE

Sows were allocated to inoculated (n = 12) or noninoculated (4) groups. Inoculated sows received intramammary administration of E coli (serotype O127) during the 24-hour period preceding parturition. Blood samples were collected from noninoculated and inoculated sows for 3 consecutive days within 3 to 11 days before farrowing and inoculation. Samples were also collected 0, 24, 48, 72, and 96 hours after farrowing and inoculation. Inoculated sows were further categorized as affected (4 sows) or nonaffected (8 sows) based on clinical signs of disease. Serum tumor necrosis factor (TNF)-alpha, plasma interleukin (IL)-6, and serum amyloid A (SAA) concentrations were measured by use of ELISA; serum haptoglobin concentration was assayed by use of a hemoglobin-binding method; and plasma cortisol concentration was determined by use of radioimmunoassay.

RESULTS

Plasma or serum concentrations of TNF-alpha, IL-6, and SAA of both categories of inoculated sows were significantly increased by 24 hours after intramammary inoculation of E coli, compared with concentrations in noninoculated sows. Concentrations of serum TNF-alpha and plasma IL-6 were significantly higher in inoculated sows that developed clinical mastitis than in nonaffected inoculated sows.

CONCLUSIONS AND CLINICAL RELEVANCE

Concentrations of TNF-alpha and IL-6 are promising markers for the identification of periparturient sows with subclinical coliform mastitis. Identification of such sows should help improve the health and survival of piglets.

Dietary 18:3ω3 influences immune function and the tissue fatty acid response to antigens and adjuvant

Alpha-linolenic acid (18:3omega3) has many important physiological functions including being beta-oxidized, serving a precursor to the synthesis of other lipids and it has immunomodulation properties. The objective of the present study was to test the effects of immunization and dietary 18:3omega3 on immune function and the fatty acid profile of immunized pig tissues. Piglets suckled from sows consuming either a control or high 18:3omega3 diet until 14 days old when they were weaned onto a similar diet as the sow and were moved to a segregated nursery for the remainder of the study. At 35 days of age, pigs on both diets (2 x 2 factorial design) received either an injection containing hen eggwhite lysozyme (HEWL), killed Mycobacterium tuberculosis and Freund's complete adjuvant (immunized) or phosphate buffered saline (PBS) (non-immunized) into the neck followed by a booster injection 2 weeks later and induction of delayed-type hypersensitivity (DTH) one week later. Immunization increased (compared to non-immunized) while the high 18:3omega3 diet decreased haptoglobin by 30% compared to pigs consuming the control diet. Immunized pigs had a seven-fold increase in antibodies to HEWL and pigs consuming the high 18:3omega3 diet also had transiently higher levels of serum antibodies. There was a diet by immunization interaction on the DTH reaction such that immunized pigs consuming the high 18:3omega3 had the largest DTH reaction. The neck muscle proximal to the site of injection of immunized pigs had 10-30% lower levels of triglyceride and phospholipid linoleic (18:2omega6) and 18:3omega3 compared to non-immunized pigs. Thus, a high 18:3omega3 intake in pigs modulates immune function and tissue fatty acids in response to immunization.

Current research on acute phase proteins in veterinary diagnosis: an overview

The acute phase proteins (APP) are a group of blood proteins that contribute to restoring homeostasis and limiting microbial growth in an antibody-independent manner in animals subjected to infection, inflammation, surgical trauma or stress. In the last two decades, many advances have been made in monitoring APP in both farm and companion animals for clinical and experimental purposes. Also, the mechanism of the APP response is receiving attention in veterinary science in connection with the innate immune systems of animals. This review describes the results of recent research on animal APP, with special reference to their induction and regulatory mechanisms, their biological functions, and their current and future applications to veterinary diagnosis and animal production.

Chronic lung inflammation affects plasma amino acid concentrations in pigs1

Metabolic changes associated with inflammatory processes and immune response can modify protein and AA requirements. Improved knowledge of these processes will provide opportunities for nutritional intervention to sustain growth and animal defense at the same time. The objective of the study was to identify AA whose metabolism is affected by chronic lung inflammation. Six pairs of littermate piglets were selected at 28 d of age on the basis of their BW. After catheterization of the jugular vein, one littermate received complete Freund's adjuvant (CFA) intravenously, whereas its littermate was injected with a sterile saline solution (CON). Piglets within a litter were pair-fed in order to avoid confounding effects of feed intake and inflammation on plasma AA concentrations. Blood samples were taken after an overnight fast and 2 h after the morning meal for 9 d. Rectal temperature, food consumption, weight gain, plasma haptoglobin, and AA concentrations were measured. The CFA injection decreased food intake, and increased body temperature and plasma haptoglobin concentration. Plasma tryptophan, glutamine, proline, glycine, tyrosine, ornithine, total AA concentrations, and the ratio of tryptophan to large neutral AA were less in CFA than in CON (P < 0.05), independent of time and meal. In contrast, plasma histidine concentration was higher (P < 0.05) in CFA than in CON pigs. Plasma serine, arginine, alanine, asparagine, and total AA concentrations were lower in CFA than in CON pigs only in the fed state (P < 0.05). Among essential AA, only plasma tryptophan concentration was lower (P < 0.01) in CFA than in CON pigs in both fasted and fed state. These results show that chronic lung inflammation affects individual AA differently and suggest that the utilization of some AA increased during chronic lung inflammation in pigs. Activation of tryptophan catabolism enzyme indoleamine 2,3-dioxygenase seems a relevant hypothesis to explain the increased tryptophan utilization, although its incorporation in acute-phase proteins and the existence of other catabolic pathways cannot be excluded.

Intramuscular injection of antigens and adjuvant preferentially decreases 18∶2n−6 and 18∶3n−3 in pig neck muscle

Linoleic (18:2n-6) and alpha-linolenic acids (18:3n-3) have many important physiological functions including immunomodulation. We tested how immunization influences the metabolism of 18:2n-6 and 18:3n-3 in the neck muscle of pigs. At 35 d old, pigs received either an intramuscular neck injection containing hen egg white lysozyme (HEWL), killed Mycobacterium tuberculosis, and Freund's complete adjuvant (immunized) or PBS (control). At 49 d old, immunized pigs received a booster injection of HEWL and Freund's incomplete adjuvant, and the control pigs received PBS into the neck. At 56 d old, all pigs received an intradermal injection of Mycobacterium bovis into the hind leg to induce a delayed-type hypersensitivity (DTH) reaction. At 57 d old, immunized pigs had a twofold increase in serum haptoglobin, a 10-fold increase in antibodies to HEWL, and the skinfold at the DTH reaction site was 10 times thicker than the controls. Both 18:2n-6 and 18:3n-3 (% composition) were approximately 25% lower in muscle TG, 40% lower in FFA, 50% lower in phospholipids, but not different in cholesteryl esters of the neck muscle of immunized pigs. The antigens in this model induce an increased response in the innate (haptoglobin), humoral (antibodies), and cellular (DTH) immune systems as well as a preferential decrease of 18:2n-6 and 18:3n-3 in the inflamed neck muscle. It appears that 18:2n-6 and 18:3n-3 are preferentially metabolized (possibly beta-oxidized) in response to antigens.

Serum haptoglobin concentration as a marker of clinical signs in finishing pigs

A case-control study of 340 finishing pigs aged 10 to 25 weeks in 15 commercial Danish pig herds was carried out to investigate serum haptoglobin concentration as an objective marker of clinical signs of disease. Pigs with different clinical signs were matched to control pigs without clinical signs with respect to herd, pen, estimated weight and gender, and each pig was subjected to a standard clinical examination. In 86 of the case-control pairs, the rectal temperature was also recorded. There was a significantly higher mean haptoglobin concentration in the serum of lame pigs (P<0.0001), pigs with respiratory disease (P=0.0004), pigs with tail or ear bites (P=0.0004) and pigs with diarrhoea (P=0.02). Similarly, a higher mean rectal temperature was recorded in lame pigs (P<0.0001), pigs with respiratory disease (P=0.002) and pigs with tail or ear bites (P=0.0003). There was a significant but low correlation between rectal temperature and haptoglobin concentration in serum (P=0.003, r=0.20). The area under the receiver-operating-characteristic curve was between 0.67 and 0.78 for the different clinical signs. The maximum simultaneous levels of sensitivity (0.61 to 0.71) and specificity (0.61 to 0.77) of serum haptoglobin for the different clinical signs were obtained at a cut-off value of 1.1 mg/ml. At a cut-off value of 1.8 mg/ml, the sensitivity decreased to 0.31 to 0.60, and the specificity increased to 0.82 to 0.86. It was not possible to define a cut-off value which classified individual pigs according to their clinical signs.

Plasma haptoglobin concentration in swine after challenge with Streptococcus suis

Eight 15-week-old pigs, reared under specific pathogen-free conditions, were inoculated with Streptococcus suis serotype 2. The animals were monitored before and after challenge by measuring rectal temperature, recording specific clinical symptoms and collecting blood samples for haptoglobin determination. Twenty-four hours after infection, the average haptoglobin plasma concentration of the animal group increased significantly and reached a maximum 4 days post-inoculation, followed by a constant mean level until the end of the trial on day 10. In spite of individual differences between the animals, an increase in haptoglobin concentration of at least 2.5 times above normal was observed in all infected pigs 1 day after challenge. Twenty-four hours after challenge, lameness was observed in five animals and an elevated body temperature was observed in seven of the eight experimental infected animals. These are the classical clinical symptoms of streptococcal infection. Haptoglobin was shown to increase in acute S. suis infection in pigs.