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1, 25-dihydroxycholecalciferol is recognized as a potent immune-modulator which can fight against the pathogens via the activation of vitamin D3 receptors (VDRs), as well as stimulating various cytokines in infectious diseases. In the present study, because of the vitamin D3 has an appropriate immunomodulatory, the effects of this vitamin on the levels of pre-inflammatory and anti-inflammatory cytokines have been investigated in calves with experimental pasteurellosis. This study was experimentally carried out on 10 Holstein crossbred male calves (2–4 months) that were divided into two groups. Prepared Pasteurella multocida (3 × 109 CFU/mL) was inoculated in the trachea with a lavage catheter and then the treatment group was injected with 1, 25-dihydroxycholecalciferol after confirming pneumonia. Blood sampling, clinical symptoms scoring and radiological evaluation were recorded for both groups at different time intervals. The prescription of, vitamin D3 to the treatment group caused a decline in clinical symptoms score and changed interstitial and alveolo-interstitial lung pattern to such a degree that it could recover in comparison with the control group. The concentrations of pro-inflammatory cytokines (i.e., IL-1β, IL-6, and TNF-α) and the chemokine (IL-8) showed a significant decrease in the treatment group while the concentration of IL-10 increased in the treatment groups following the vitamin D3 injection (P = .001). The evidence from the current study suggests that vitamin D3 exert the immunomodulatory effects in infectious diseases through the regulation of cytokines and activation of VDR pathways to produce antimicrobial peptides.

We aimed to compare Toll-like receptors (TLR) and cytokines expression in local Piau breed and a Commercial line (Landrace × Large White crossbred) pigs in response to vaccination against Pasteurella multocida type D. Seronegative gilts for Pasteurella multocida type D and Mycoplasma hyopneumoniae were used, from which peripheral blood mononuclear cells (PBMC) were collected in four time points (T0, T1, T2 and T3; before and after each vaccination dose). For bronchoalveolar lavage fluid cells (BALF), we set groups of vaccinated and unvaccinated animals for both genetic groups. Gene expression was evaluated on PBMC and BALF. In PBMC, when we analyzed time points within breeds, significant differences in expression for TLRs and cytokines, except TGFβ, were observed for Commercial animals. For the Piau pigs, only TGFβ showed differential expression. Comparing the expression among genetic groups, the Commercial pigs showed higher expression for TLRs after first vaccination dose, while for IL2, IL6, IL12 and IL13, higher expression was also observed in T3 and IL8 and IL10, in T1 and T3. Still comparing the breeds, the crossbred animals showed higher expression for TNFα in T1 and T2, while for TGFβ only in T2. For gene expression in BALF, vaccinated Commercial pigs showed higher expression of TLR6, TLR10, IL6, IL8, IL10, TNFα and TGFβ genes than vaccinated Piau pigs. The Commercial line pigs showed higher sensitivity to vaccination, while in local Piau breed lower responsiveness, which may partly explain genetic variability in immune response and will let us better understand the tolerance/susceptibility for pasteurellosis.

The antimicrobial susceptibilities and serotype distribution of 310 Mannheimia haemolytica isolates obtained from cattle with bovine respiratory disease during 2002-2010 were investigated. Of the 310 isolates, 198 (63.9%) were resistant to at least one of the 16 tested antimicrobial agents. The resistance rates for ampicillin, amoxicillin, dihydrostreptomycin, kanamycin, oxytetracycline, doxycycline, chloramphenicol, thiamphenicol, nalidixic acid, enrofloxacin, and danofloxacin were 20.3%, 14.5%, 43.5%, 23.5%, 24.8%, 21.9%, 23.2%, 23.9%, 47.1%, 18.7%, and 18.7%, respectively. Almost 90% of the isolates belonged to three serotypes (serotypes A1, A2, and A6), and the relative prevalence of serotype A6 increased significantly over the last decade. Compared with bacteria belonging to other serotypes, bacteria belonging to serotype A6 exhibited a significantly higher antimicrobial resistance rates (χ2 test, p

In order to develop novel immunoadjuvants to boost immune response of conventional vaccines, experiments were conducted to investigate the regulating effects of porcine interleukin-6 gene and CpG motifs as the molecular adjuvants on immune responses of mice that were co-inoculated with trivalent vaccines against Swine fever, the Pasteurellosis and Erysipelas suis. Synthetic oligodeoxynuleotides containing CpG motifs were ligated into pUC18, forming recombinant pUC18-CpG plasmid. Eukaryotic plasmid expressing porcine interleukin-6 (VPIL-6) were also constructed as molecular adjuvants in an attempt to enhance levels of immune responses of mice co-administered with the trivalent vaccines in this paper. The cellular and humoral immune responses of mice were systematically analysed, and the experimental results were observed that the number of white blood cells, monocytes, granuloytes and lymphocytes significantly increased, respectively, in the mice immunized with VPIL-6, compared with those of the control; the IgG content and titre of specific antibodies to the trivalent vaccine mounted remarkably in the sera from the VPIL-6 vaccinated mice; the proliferation of lymphocytes and induced IL-2 activities were significantly increased in the vaccinated groups. The above-mentioned immune responses of mice co-inoculated with pUC18-CpG plasmid were significantly stronger than those of co-inoculated with pUC18 plasmid, suggesting that the immunostimulatory effect of oligodeoxynuleotides CpG is closely connected with the number of CpG motifs. These results suggest that the porcine IL-6 gene and CpG motifs could be employed as effective immunoadjuvants to elevate immunity to conventional vaccines.

The gram-negative bacterium Pasteurella multocida causes pneumonic and systemic pasteurellosis in bovids for which vaccines are either unavailable or inadequate. The work assessed whether an intranasal P. multocida challenge in mice might provide a model of infection for future vaccine development work. Clinical, pathological and biochemical responses were compared in seven strains of mice challenged with a virulent bovine pneumonic isolate of P. multocida A:3. Six mouse strains (Porton, CD-1, BALB/c, VM, C57BL/10 and C57BL/6) developed clinical signs of pneumonic disease and variable pneumonic lesions 41-70 h post-infection. In contrast, mouse strain RIII became septicaemic within 36 h post-infection. Concentrations of plasma acute phase proteins and serum lipopolysaccharide increased in all mice after infection, and the main or interaction effect of mouse strain and infection status was statistically significant (P

The concentrations of tumour necrosis factor-alpha (TNF alpha), serum amyloid A (SAA) and haptoglobin were determined in serum samples taken from four calves in the 10 hours after their intra-tracheal inoculation with Pasteurella haemolytica serotype A1. The concentration of haptoglobin did not increase but the concentration of SAA rose progressively from within two hours of inoculation. The concentration of TNF alpha reached a peak in all the animals two hours after inoculation but had returned to undetectable levels after a further four hours. TNF alpha is likely to be an important mediator of the acute phase response in cattle and SAA is a more rapid bovine acute phase protein than haptoglobin in its response to infection with P haemolytica.

Mice were experimentally infected with Pasteurella multocida serotype A1 to study the cytokine profiles, host cell apoptosis and sequential pathology at different hours of post-infection. Infected mice were dull, anorectic and depressed. A transient leukocytopenia followed by progressive leukocytosis was observed in the course of infection. Serum cytokine profiles showed significantly (P

The study aimed to establish an experimental model to investigate the pathogenesis of lung infection by Pasteurella multocida, an important cause of bovine respiratory disease. An experimental model is required to assist the development of an effective vaccine. Sixteen 8-week-old calves were challenged intratracheally with 10(9) or 10(10) colony forming units of P. multocida in either 60 or 300 ml saline in a 2 x 2 factorial experiment. All animals became dull within 2-6h post-infection (p.i.) and two calves were killed humanely because of suspected endotoxic shock. Remaining animals showed increased respiratory rates by 15-20 h p.i. and, at 23 h p.i., calves given the high dose, high volume challenge showed higher (P < 0.05) rectal temperatures. From 24 to 36 h p.i., clinical signs decreased in a majority of animals. Plasma haptoglobin concentrations increased (P < 0.05) in calves given the high volume challenge irrespective of the number of bacteria. At post-mortem examination (4d p.i.), lung lesions, mainly in the apical lobes, were found in all calves. Histopathological examination showed areas of purulent pneumonia with a tendency to abscessation and inflamed interlobular septa characterised by accumulation of neutrophils and oedema. The clinical and pathological responses described were typical of bovine pneumonic pasteurellosis.

Sixteen 8- to 9-week-old Pasteurella multocida -free New Zealand White rabbits were divided into two equal groups. The first group was inoculated intranasally with P multocida serotype D:1 strain and the second group that was inoculated with phosphate-buffered saline ( PBS ) only was used as a control group. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits in group 1 and from tracheal swabs of seven rabbits in this group. Four rabbits in group 1 died with clinical signs of septicaemia, two rabbits had mucopurulent nasal discharge and pneumonic lesions and the other two did not show any clinical signs or gross lesions. The ultrastructural changes detected were deciliation or clumping of cilia of ciliated epithelium, cellular swelling, vacuolation and sloughing. The subepithelial capillaries showed congestion, intravascular fibrin deposition, platelets aggregation and endothelial injury. Pasteurella multocida was observed attached to the injured endothelial cells. Heterophils, mast cells, vacuolated monocytes and macrophages infiltrated the lamina propria and between the degenerated epithelial cells.

Thermoplastic tissue chambers were implanted subcutaneously in the paralumbar fossae of 10 calves. Concentrations of α 1 -acid glycoprotein (AAG) and albumin in serum and subcutaneous tissue chamber fluid were measured before and after inoculation of Pasteurella haemolytica into tissue chambers. Two months after implantation, serum and tissue chamber fluid samples were collected and all tissue chambers were then inoculated with P haemolytica . Additional serum and chamber fluid samples were collected two, four, six and 10 days after inoculation. The concentrations of AAG and albumin in the samples were measured by radial immunodiffusion assay and the bromcresol method, respectively. P haemolytica inoculation resulted in an increase in the serum and chamber fluid AAG concentrations and an increase in chamber fluid albumin concentrations, suggesting that the proportion of drugs bound to serum and interstitial proteins may be affected by P haemolytica infection.

Pneumonic pasteurellosis has been reproduced in conventional, weaned, Friesian-cross calves using a strain of Pasteurella haemolytica biotype A, serotype 1 (P haemolytica Al) isolated from a pathologically confirmed incident of bovine pneumonic pasteurellosis. The major clinical findings were pyrexia, hyperpnoea, tachypnoea, nasal discharge and reduced appetite. Fibrinous pneumonia was present in the lungs of animals at necropsy on days 2 and 3 after initial infection while by days 9 and 10 after initial infection many of the areas of fibrinous pneumonia were confined by a fibrous capsule forming well defined nodules. During the experiment natural transmission of the infecting strain of P haemolytica Al occurred in two control calves which developed a condition identical to that in the artificially infected calves. P haemolytica AI was repeatedly recovered from the nasopharynx of infected calves and at necropsy throughout the upper and lower respiratory tracts. Seroconversion, as measured by indirect haemagglutination, to the organism developed in all infected calves by days 9 and 10 after initial infection. The clinical, microbiological and pathological findings were identical to those seen in field incidents of bovine pneumonic pasteurellosis involving recently housed, weaned, single-suckled calves.

A whole blood lymphocyte stimulation assay to study cell-mediated immune responses in bovine pasteurellosis was developed. Peripheral blood lymphocytes from cattle artificially immunised with three Asiatic haemorrhagic septicaemia strains of Pasteurella multocida exhibited higher stimulation indices when incubated with antigen preparations from homologous strains than with the heterologous shipping fever strain. Lymphocytes from cattle immunised with the shipping fever strain of P multocida exhibited a higher stimulation index when incubated with an antigen preparation from the homolgous strain than with antigen preparations from heterologous haemorrhagic septicaemia strains. These results suggest that immunogenic differences exist between the haemorrhagic septicaemia strains and the shipping fever strain of P multocida. An assay using turkey whole blood lymphocytes was also developed. The use of small amounts of whole blood, microtitre plates, either 125I iododeoxyuridine or 3H-thymidine as the labelling agent, and a multiple cell-culture harvester makes the method simple, rapid and suitable for the study of immune competence and cell-mediated immune responses in turkeys on a flock basis.

Mice given 60 micrograms iron, as aqueous ferric ammonium citrate, intravenously were more susceptible than untreated controls to intraperitoneal infection with T serotypes of Pasteurella haemolytica as shown by significant reductions in LD50 values. Iron injection has advantages over administration of bacteria suspended in mucin for studies of P haemolytica infection in mice.

The serotypes of 406 strains of Pasteurella haemolytica were determined. These came from cases of pasteurellosis in sheep of all ages. Serotype A2 was the most frequent and comprised 33 per cent of all strains recovered. Serotypes T3, T4 and T10 comprised 16, 14 and 12 per cent of the total respectively. Serotypes A1 and A6 contributed 5 per cent each, A7, 18, A9, A11 and A12 a total of 8 per cent collectively, serotype A5 was not isolated at all while 6 per cent of strains were serologically untypable. More strains were received during September, October and November than at any other three-month period and in these months the T biotype predominated.

Single strains of serotypes A1, A2, A7 and A9 of Pasteurella haemolytica were separately used in combination with Mycoplasma ovipneumoniae to reproduce pneumonia. Macroscopically and microscopically the pneumonias associated with individual serotypes were similar and it is concluded that serotypes of P haemolytica isolated with low frequency in field disease may be equally virulent to common serotypes.