Immuno-modulation and anti-inflammatory benefits of antibiotics: The example of tilmicosin
André G. Buret

Abstract — Exagerated immune responses, such as those implicated in severe inflammatory reactions, are costly to the metabolism. Inflammation and pro-inflammatory mediators negatively affect production in the food animal industry by reducing growth, feed intake, reproduction, milk production, and metabolic health. An ever-increasing number of findings have established that antibiotics, macrolides in particular, may generate anti-inflammatory effects, including the modulation of pro-inflammatory cytokines and the alteration of neutrophil function. The effects are time- and dose-dependent, and the mechanisms responsible for these phenomena remain incompletely understood. Recent studies, mostly using the veterinary macrolide tilmicosin, may have shed new light on the mode of action of some macrolides and their anti-inflammatory properties. Indeed, research findings demonstrate that this compound, amongst others, induces neutrophil apoptosis, which in turn provides anti-inflammatory benefits. Studies using tilmicosin model systems in vitro and in vivo demonstrate that this antibiotic has potent immuno-modulatory effects that may explain why at least parts of its clinical benefits are independent of anti-microbial effects. More research is needed, using this antibiotic and others that may have similar properties, to clarify the biological mechanisms responsible for antibiotic-induced neutrophil apoptosis, and how this, in turn, may provide enhanced clinical benefits. Such studies may help establish a rational basis for the development of novel, efficacious, anti-microbial compounds that generate anti-inflammatory properties in addition to their antibacterial effects.

Characterization of Salmonella Typhimurium isolates associated with septicemia in swine
Nadia Bergeron, Jonathan Corriveau, Ann Letellier, France Daigle, Sylvain Quessy

Abstract — Salmonella Typhimurium is frequently isolated from pigs and may also cause enteric disease in humans. In this study, 33 isolates of S. Typhimurium associated with septicemia in swine (CS) were compared to 33 isolates recovered from healthy animals at slaughter (WCS). The isolates were characterized using phenotyping and genotyping methods. For each isolate, the phage type, antimicrobial resistance, and pulsed-field gel electrophoresis (PFGE) DNA profiles were determined. In addition, the protein profiles of each isolate grown in different conditions were studied by Coomassie Blue-stained sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot. Various phage types were identified. The phage type PT 104 represented 36.4% of all isolates from septicemic pigs. Resistance to as many as 12 antimicrobial agents, including some natural resistances, was found in isolates from CS and WCS. Many genetic profiles were identified among the PT 104 phage types. Although it was not possible to associate one particular protein with septicemic isolates, several highly immunogenic proteins, present in all virulent isolates and in most isolates from clinically healthy animals, were identified. These results indicated that strains associated with septicemia belong to various genetic lineages that can also be recovered from asymptomatic animals at the time of slaughter.

Identification and differentiation of Taylorella equigenitalis and Taylorella asinigenitalis by lipopolysaccharide O-antigen serology using monoclonal antibodies
Brian W. Brooks, Cheryl L. Lutze-Wallace, Leann L. MacLean, Evgeny Vinogradov, Malcolm B. Perryu

Abstract — Lipopolysaccharides (LPSs) from Taylorella equigenitalis, the causative agent of contagious equine metritis, and T. asinigenitalis were compared by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Lipopolysaccharide profiles of 11 T. equigenitalis strains were similar, but different from the profiles of 3 T. asinigenitalis strains, and the profiles of 2 T. asinigenitalis strains were similar to each other. The serological specificities of the LPSs from these 14 strains were examined by immunoblotting and enzyme-linked immunosorbent assay with monoclonal antibodies (MAbs) to the LPSs of the T. equigenitalis and T. asinigenitalis type strains and T. asinigenitalis strain 2329-98. A MAb to T. equigenitalis LPS O-polysaccharide (O-PS) (M2560) reacted with LPSs from all T. equigenitalis strains but did not react with LPSs from the 3 T. asinigenitalis strains or with 43 non-Taylorella bacteria. Three MAbs to the T. asinigenitalis type strain LPS O-PS or core epitopes (M2974, M2982, M3000) reacted with the homologous strain and T. asinigenitalis strain Bd 3751/05, but not with any of the other bacteria. Five MAbs to T. asinigenitalis 2329-98 LPS O-PS or core epitopes (M2904, M2907, M2910, M2923, M2929) reacted only with this strain. Proton nuclear magnetic resonance spectra of the O-PSs of the type strains of T. equigenitalis and T. asinigenitalis provided fingerprint identification and differentiation of these 2 organisms. The serological results were consistent with our previous finding that the O-antigen of the type strain of T. equigenitalis, being a linear polymer of disaccharide repeating [?4)-a-L-GulpNAc3NAcA-(1?4)-ß-D-ManpNAc3NAcA-(1?] units, differs from that of the T. asinigenitalis O-antigen polymer that is composed of repeating [?3)-ß-D-QuipNAc4NAc-(1?3)-ß-D-GlcpNAmA-(1?] units. Lipopolysaccharide O-PS could be a specific marker for identification and differentiation of T. equigenitalis and T. asinigenitalis, and provide the basis for the development of specific detection assays for T. equigenitalis.

Protective potential of an attenuated Pasteurella multocida, which expresses only the N-terminal truncated fragment of P. multocida toxin
Jayoung Seo, Semi Lee, Hyoju Pyo, Jaeil Lee, Taejung Kim

Abstract — Pasteurella multocida serogroup D causes progressive atrophic rhinitis in pigs and produces a potent, intracellular, mitogenic toxin known as P. multocida toxin (PMT), which is encoded by the toxA gene. Highly toxic to cells, PMT is a poor antigen and becomes more immunogenic after its native structure has been destroyed. Previously, we found that the N-terminal fragment of PMT (N-PMT) can induce a strong immune response that is protective against wild-type challenge. Here, an attenuated P. multocida mutant expressing only N-PMT was developed and its protective effect was evaluated. The mutant provides protective immune responses against bacterial and toxin challenges, and so is a good live vaccine candidate.

Activation of the ovine hypothalamic-pituitary-adrenal axis and febrile response by interleukin-6: A comparative study with bacterial lipopolysaccharide endotoxin
Niel A. Karrow, Qiumei You, Carl McNicoll, Jack Hay

Abstract — Sheep were subjected to immune challenge with either recombinant human interleukin-6 (rhIL-6; 2.0 µg/kg; n = 5), Escherichia coli lipopolysaccharide (LPS) endotoxin (400 ng/kg; n = 7), or saline (n = 6) to determine if IL-6 activates the febrile and hypothalamic-pituitary-adrenal axis (HPAA) responses in sheep, and to compare these responses with those associated with endotoxemia. Blood was collected over time to measure plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations as indicators of HPAA activity. Unlike LPS, rhIL-6 was not pyrogenic in sheep at this challenge dose. In contrast, rhIL-6 elicited ACTH and cortisol responses that peaked earlier than those induced by LPS. These results suggest that this dose of IL-6, alone, is not sufficient to elicit the febrile response in sheep, however, it is a potent activator of the ovine HPAA response.

The effect of body position, sedation, and thoracic bandaging on functional residual capacity in healthy deep-chested dogs
Elizabeth A. Rozanski, Daniela Bedenice, Jennifer Lofgren, Julie Abrams, Jonathan Bach, Andrew M. Hoffman

Abstract — The objective of this study was to determine the effect of body position, chest wrap, and sedation on functional residual capacity (FRC) in 6 healthy dogs. Functional residual capacity was determined by helium dilution (re-breathing) whilst in different clinically relevant conditions. These conditions included the standing (sternal) and lateral positions in unsedated dogs and then again both standing and lateral following chest bandaging, and sedation with acepromazine, IV and butorphanol, IV. The mean FRC at each measurement point was determined, as was the change in FRC (delta FRC) from one measurement point to another. Analysis of variance (ANOVA) with repeated measures with Fisher’s LSD post hoc test was used to evaluate the effect of interventions. The differences in delta FRC were evaluated using a t-test or Wilcoxon rank-sum test. P < 0.05 was considered significant. The mean FRC at baseline, defined as standing, unsedated and unwrapped, was 75.3 ± 23.8 mL/kg. Body position or sedation had the most profound effect on FRC with right lateral recumbency lowering FRC by a median of 20.4 mL/kg and sedation lowering FRC by a median of 19.8 mL/kg. Common clinical procedures and positioning result in lowered FRC in healthy deep-chested dogs. In critically ill or injured dogs, the iatrogenic loss of FRC through chest bandaging, sedation, or body position may be clinically relevant.

Degradation of foot-and-mouth disease virus during composting of infected pig carcasses
J. Guan, M. Chan, C. Grenier, B.W. Brooks, J.L. Spencer, C. Kranendonk, J. Copps, A. Clavijo

Abstract — The objective of this study was to investigate the inactivation and degradation of foot-and-mouth disease (FMD) virus during composting of infected pig carcasses as measured by virus isolation in tissue culture and by real-time reverse transcriptase polymerase chain reaction (RRT-PCR). Three FMD-infected pig carcasses were composted in a mixture of chicken manure and wood shavings in a biocontainment level 3 facility. Compost temperatures had reached 50°C and 70°C by days 10 and 19, respectively. Under these conditions, FMD virus was inactivated in specimens in compost by day 10 and the viral RNA was degraded in skin and internal organ tissues by day 21. In comparison, at ambient temperatures close to 20°C, FMD virus survived to day 10 in the skin tissue specimen from the pig that had the highest initial level of viral RNA in its tissues and the viral RNA persisted to day 21. Similarly, beta-actin mRNA, tested as a PCR control, persisted to day 21 in specimens held at ambient temperatures, but it was degraded in the remnants of tissues recovered from compost on day 21. Results from this study provide evidence that composting could be used for safe disposal of pig carcasses infected with FMD virus.

Pulmonary intravascular macrophages and endotoxin-induced pulmonary pathophysiology in horses
Karin Aharonson-Raz, Baljit Singh

Abstract — Endotoxemia causes significant mortality and morbidity in horses. The mechanisms underlying this complex pathophysiology remain unclear. Therefore, effective tools to treat endotoxemia in horses are lacking. Furthermore, the multifactorial and multiorgan pathophysiology of equine endotoxemia has not been fully addressed, especially the lung injury associated with endotoxemia. Within the context of the broader picture of endotoxemia and lung injury, we offer a perspective on the roles of pulmonary intravascular macrophages in endotoxin-induced lung inflammation in horses.

Increased risk of chronic wasting disease in Rocky Mountain elk associated with decreased magnesium and increased manganese in brain tissue
Stephen N. White, Katherine I. O’Rourke, Thomas Gidlewski, Kurt C. VerCauteren, Michelle R. Mousel, Gregory E. Phillips, Terry R. Spraker

Abstract — Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of Rocky Mountain elk in North America. Recent studies suggest that tissue and blood mineral levels may be valuable in assessing TSE infection in sheep and cattle. The objectives of this study were to examine baseline levels of copper, manganese, magnesium, zinc, selenium, and molybdenum in the brains of Rocky Mountain elk with differing prion genotypes and to assess the association of mineral levels with CWD infection. Elk with leucine at prion position 132 had significantly lower magnesium levels than elk with 2 copies of methionine. Chronic wasting disease-positive elk had significantly lower magnesium than control elk. The incorporation of manganese levels in addition to magnesium significantly refined explanatory ability, even though manganese alone was not significantly associated with CWD. This study demonstrated that mineral analysis may provide an additional disease correlate for assessing CWD risk, particularly in conjunction with genotype.

Kinetics and role of antibodies against intimin ß in colostrum and in serum from goat kids and longitudinal study of attaching and effacing Escherichia coli in goat kids
José A. Orden, Ricardo De la Fuente, María Yuste, Susana Martínez-Pulgarín, José A. Ruiz-Santa-Quiteria, Pilar Horcajo, Antonio Contreras, Antonio Sánchez, Juan C. Corrales, Gustavo Domínguez-Bernal

Abstract — The presence of antibodies to the intimin ß-binding region (Int280-ß) of attaching and effacing Escherichia coli (AEEC) in serum from 20 goat kids from 2 herds, as well as in goat colostrum, was investigated by enzyme-linked immunosorbent assay. In addition, the onset and subsequent pattern of shedding of AEEC from the same goat kids over a 6-mo period was investigated. All the colostrum and serum samples tested contained antibodies against Int280-ß. The association between the antibody titer and the isolation of AEEC suggests that antibodies to intimin ß do not prevent colonization of the intestine by AEEC in goat kids. The AEEC were generally shed only transiently. Most AEEC isolated from the kids belonged to serogroup O26. Three isolates belonged to serogroup O157. These data show that goat kids may be a reservoir of AEEC that are potentially pathogenic for humans.

Isolation of Escherichia coli from piglets in South Korea with diarrhea and characteristics of the virulence genes
Yeong Ju Kim, Ji Hee Kim, Jin Hur, John Hwa Lee

Abstract — Escherichia coli was isolated from the feces of 122 piglets with diarrhea on 55 farms in Korea. The virulence genes of each isolate were characterized by polymerase chain reaction (PCR). Of the 562 isolates, 191 carried 1 or more of the virulence genes tested for in this study. Of the 191 isolates, 114 (60%) carried 1 or more of the genes for enterotoxigenic E. coli (ETEC) fimbriae F4, F5, F6, F18, and F41 and ETEC toxins LT, STa, and STb, 57 (30%) carried 1 or more of the genes for the Shiga-toxin-producing E. coli (STEC) toxins Stx1, Stx2, and Stx2e, and 21% and 37% carried the gene for enteropathogenic E. coli intimin and for enteroaggregative E. coli toxin, respectively. Collectively, our results indicate that other pathotypes of E. coli as well as ETEC can be strongly associated with diarrhea in piglets. In addition, detection of the genes for Stx1 and Stx2 indicates that pigs are reservoirs of human pathogenic STEC.

Pleiotropic effects of polysaccharide capsule loss on selected biological properties of Streptococcus suis
Shin-Ichi Tanabe, Laetitia Bonifait, Nahuel Fittipaldi, Louis Grignon, Marcelo Gottschalk, Daniel Grenier

Abstract — In this study, an unencapsulated Streptococcus suis mutant was used to investigate the pleiotropic effects resulting from capsule loss. The capsule deficient mutant of S. suis acquired a biofilm-positive phenotype, which was associated with significantly increased cell surface hydrophobicity. Cell-associated fibrinogen-binding and chymotrypsin-like activities were decreased in the unencapsulated mutant. The mutant did not differ significantly from the encapsulated parent strain for minimal inhibitory concentrations to penicillin G, ampicillin, and tetracycline. However, while the encapsulated strain was highly resistant to the bactericidal action of penicillin G and ampicillin, the unencapsulated mutant was approximately 60-fold more sensitive. Compared with the parent strain, the unencapsulated mutant induced a much higher inflammatory response in monocyte-derived macrophages resulting in an increased secretion of tumor necrosis factor (TNF)-a, interleukin (IL)-1ß, IL-6, and IL-8. The capsule appears to hinder important adhesins or hydrophobic molecules that mediate biofilm formation, as well as cell wall components capable of stimulating immune cells.

Rapid serodiagnosis with the use of surface plasmon resonance imaging for the detection of antibodies against major surface protein A of Mycoplasma synoviae in chickens
Kiseok Oh, Semi Lee, Jayoung Seo, Dongwoo Lee, Taejung Kim

Abstract — Mycoplasma synoviae, a major worldwide pathogen in poultry, causes respiratory tract infection and arthritis in chickens and turkeys. Two major surface antigens of M. synoviae are encoded by a single gene, vlhA (variably expressed lipoprotein and hemagglutinin). The gene product is cleaved post-translationally to yield the lipoprotein major surface protein (MSP) B (MSPB) and the hemagglutinin MSPA. The availability of MSPA as an antigen for serodiagnosis was studied by means of a protein chip based on surface plasmon resonance imaging (SPRi). The diagnostic potential of SPRi for measurement of levels of antibody to MSPA was compared with that of a conventional enzyme-linked immunosorbent assay (ELISA) kit. The results from SPRi, a process that took only 1 h, were similar to those from ELISA. Therefore, MSPA can be used as an antigen for serologic studies, and SPRi, a label-free and high-throughput method, may be a valuable tool in avian serodiagnostic studies.

Bighorn sheep fetal lung cell line for detection of respiratory viruses
Sudarvili Shanthalingam, Christina Topliff, Clayton L. Kelling, Subramaniam Sri

Abstract — Pneumonia is an important disease of bighorn sheep (BHS) that is primarily responsible for the drastic decline in numbers of these animals in North America. Members of the genus Mannheimia and Pasteurella have frequently been isolated from the pneumonic lungs of BHS. Antibodies to several respiratory viruses, including bovine parainfluenza virus 3 (BPIV-3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and bovine herpesvirus 1 (BoHV-1), have been detected in herds of BHS. The availability of BHS fetal lung cell lines is likely to enhance the chances of isolation of these viruses. Here we report the development of such a cell line. This line is permissive for BPIV-3, BRSV, BVDV, and BoHV-1 infection, as revealed by an enzyme immunoassay of virus-infected cells with antibodies specific for each of these viruses. This cell line should be valuable for detecting these 4, and possibly other, respiratory viruses in BHS.

Influence of parity and litter size on gestation length in beagle dogs
Makoto Seki, Norio Watanabe, Kenyo Ishii, Yoh-ichi Kinoshita, Takehiro Aihara, Shuji Takeiri, Takeshige Otoi

Abstract — This study was conducted to investigate the effects of parity and litter size on gestation length in beagle bitches. The mean duration of the initial elevation (> 2 ng/mL) in progesterone concentrations after the onset of proestrus was shorter (P < 0.05) in bitches without (nulliparous) whelping experience than in bitches with (multiparous) whelping experience (6.9 d versus 8.0 d). When calculated as the interval between the day of initial elevation in progesterone concentrations and the day of whelping, the gestation length in the nulliparous bitches was noted to be similar to that in the multiparous bitches (64.3 d versus 64.2 d). No significant correlation between gestation length and litter size was observed in any of the bitches. Our results indicate that the gestation length in beagle bitches is not affected by parity or litter size.