Serological response to Pasteurella multocida NanH sialidase in persistently colonized rabbits

Screening and purification of NanB sialidase from Pasteurella multocida with activity in hydrolyzing sialic acid Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal

Study on sialidases as antiviral agents has been widely performed, but many types of sialidase have not been tested for their antiviral activity. Pasteurella multocida NanB sialidase is one such sialidase that has never been isolated for further research. In this study, the activity of NanB sialidase was investigated in silico by docking the NanB sialidase of Pasteurella multocida to the Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal ligands. Additionally, some local isolates of Pasteurella multocida, which had the NanB gene were screened, and the proteins were isolated for further testing regarding their activity in hydrolyzing Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal. Silico studies showed that the NanB sialidase possesses an exceptional affinity towards forming a protein–ligand complex with Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal. NanB sialidase of Pasteurella multocida B018 at 0.129 U/mL and 0.258 U/mL doses can hydrolyze Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal better than other doses. In addition, those doses can inhibit effectively H9N2 viral binding to red blood cells. This study suggested that the NanB sialidase of Pasteurella multocida B018 has a potent antiviral activity because can hydrolyze sialic acid on red blood cells surface and inhibit the H9N2 viral binding to the cells.

Single level posterolateral lumbar fusion in a New Zealand White rabbit (Oryctolagus cuniculus) model: Surgical anatomy, operative technique, autograft fusion rates, and perioperative care

INTRODUCTION

The posterolateral lumbar fusion (PLF) New Zealand White (NZW) (Oryctolagus cuniculus) rabbit model is a long-standing surgical technique for the preclinical evaluation of materials for spinal fusion. A detailed understanding of lumbar spine anatomy and perioperative care requirements of rabbits is imperative for correct execution of the model both scientifically and ethically. This study describes the preoperative procedures and surgical techniques used in single level PLF in a NZW rabbit model as it pertains to the animal husbandry, lumbar spine anatomy, anesthesia, surgical approach, and perioperative care of rabbits in a research setting.

MATERIALS AND METHODS

We describe the surgical technique and perioperative patient care for single level PLF in a NZW rabbit model. Medical records from a single research facility were retrospectively reviewed for adult NZW rabbits that underwent single level PLF (L4-L5) between January 2016 and December 2019. The number of lumbar vertebrae per rabbit, fusion rates at 12 weeks using iliac crest autograft and complications are reported. Skeletal maturity was confirmed by preoperative fluoroscopic and radiographic documented closure of hindlimb physes.

RESULTS

The PLF rabbit surgical model and perioperative patient care is described. PLF was performed in 868 adult female entire NZW rabbits. The majority of rabbits had seven lumbar vertebrae (620/868; 71.4%), followed by six (221/868; 25.5%), and eight (27/868; 3.1%). Fusion rates at 12 weeks for PLF using iliac crest autograft as assessed by manual palpation and radiographic assessment was 76.9% and 70.0%, respectively. Postoperative complications included occasional partial autograft site wound dehiscence due to self-trauma.

CONCLUSIONS

For PLF rabbit models, a detailed understanding of the surgical technique, rabbit lumbar anatomy including number of lumbar vertebrae, and dietary and husbandry requirements of rabbits, is essential for execution of the model and animal welfare.

Complete Genome Sequence Analysis and Characterization of Selected Iron Regulation Genes of Pasteurella Multocida Serotype A Strain PMTB2.1

Although more than 100 genome sequences of Pasteurella multocida are available, comprehensive and complete genome sequence analysis is limited. This study describes the analysis of complete genome sequence and pathogenomics of P. multocida strain PMTB2.1. The genome of PMTB2.1 has 2176 genes with more than 40 coding sequences associated with iron regulation and 140 virulence genes including the complete tad locus. The tad locus includes several previously uncharacterized genes such as flp2, rcpC and tadV genes. A transposable phage resembling to Mu phages was identified in P. multocida that has not been identified in any other serotype yet. The multi-locus sequence typing analysis assigned the PMTB2.1 genome sequence as type ST101, while the comparative genome analysis showed that PMTB2.1 is closely related to other P. multocida strains with the genomic distance of less than 0.13. The expression profiling of iron regulating-genes of PMTB2.1 was characterized under iron-limited environment. Results showed significant changes in the expression profiles of iron-regulating genes (p < 0.05) whereas the highest expression of fecE gene (281 fold) at 30 min suggests utilization of the outer-membrane proteins system in iron acquisition at an early stage of growth. This study showed the phylogenomic relatedness of P. multocida and improved annotation of important genes and functional characterization of iron-regulating genes of importance to the bacterial growth.

Anti-Inflammatory, Immunomodulatory, and Antioxidant Activities of Allicin, Norfloxacin, or Their Combination against Pasteurella multocida Infection in Male New Zealand Rabbits

The present study investigated the efficacy of allicin as an antibacterial, anti-inflammatory, antioxidant, and immunostimulant agent in reducing the severity of Pasteurella multocida (P. multocida) type B infection in rabbits. Fifty New Zealand rabbits, 5 weeks old, were divided equally into five groups. Except for group 1, all groups were intranasally infected with P. multocida type B (2 × 10⁵ colony forming units/ml/rabbit). Then, group 3 rabbits were orally treated with allicin (50 mg/kg BW) for 5 days, group 4 rabbits received a single oral dose of norfloxacin 30% (100 mg/kg BW), while group 5 rabbits were treated with a combination of norfloxacin and allicin. Hematological, serum biochemical, inflammatory cytokine, immunological, and histopathological analyses were performed. Results revealed that rabbits, infected with P. multocida type B, exhibited macrocytic hypochromic anemia and leukocytosis with a significant elevation in the phagocytic percentage and index. Moreover, significant reductions in serum total protein, albumin, globulin, and immunoglobulin (IgG and IgM) levels were observed in infected rabbits. Infected rabbits showed significant increases in serum inflammatory cytokine (TNF-α and IL-6), alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and serum bilirubin (total, direct, and indirect) levels. Further, P. multocida infection induced oxidative stress as demonstrated by the significant reduction in serum levels of reduced glutathione and superoxide dismutase enzyme and marked elevation in serum malondialdehyde. Treatment with allicin, norfloxacin, or their combination significantly ameliorated the alterations in all studied parameters. In conclusion, allicin could ameliorate the inflammation and oxidative stress, induced by P. multocida type B infection in rabbits.

Alternative treatment of serious and mild Pasteurella multocida infection in New Zealand White rabbits

Background

Pasteurella multocida causes numerous economically relevant diseases in livestock including rabbits. Immunisation is only variably effective. Prophylactic antibiotics are used in some species but are contra-indicated in rabbits, due to their adverse effects on the rabbit microbiota. There is therefore a substantial need for alternative forms of infection control in rabbits; we investigated the effect of oral β-glucan on P. multocida infection in this species.

Results

Thirthy-five New Zealand White rabbits were randomly divided into five groups of seven animals. Three groups were inoculated with Pasteurella multocida intranasally (in.), a physiologically appropriate challenge which reproduces naturally acquired infection, and received either (1–3), (1–6) β-glucans or placebo. Four other groups were inoculated both in. and intramuscularly (im.), representing a supra-physiological challenge, and received either (1–3), (1–6) β-glucans, antibiotic or placebo. β-glucans given prophylactically were highly effective in protecting against physiological (in.) bacterial challenge. They were less effective in protecting against supra-physiological bacterial challenge (in. and im.), although they extended survival times. This latter finding has practical relevance to breeders as it extends the window in which heavily infected and symptomatic animals can be salvaged with antibiotics.

Conclusions

In our study, (1–3), (1–6) β-glucans were highly effective in protecting against a model of naturally acquired P. multocida infection and extended survival times in the supra-physiological model. Enrofloxacin was effective in protecting against supra-physiological infection. We are currently reviewing the use of combined prophylaxis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0276-6) contains supplementary material, which is available to authorized users.

Diagnostic and typing options for investigating diseases associated with Pasteurella multocida

Pasteurella multocida is responsible for major animal diseases of economic significance in both developed and developing countries whereas human infections related to this bacterium are infrequent. Significantly, development of a carrier status or latent infections plays a critical role in the epidemiology of these diseases. Aiming at increased knowledge of these infections, we examine potential diagnostic and selected typing systems for investigating diseases caused by P. multocida. Detection of P. multocida from clinical specimen by; (i) isolation and identification, (ii) polymerase chain reaction (PCR), iii) specific hybridisation probes, (iv) serological tests and (v) other alternative methods is critically evaluated. These detection systems provide a wide spectrum of options for rapid diagnosis and for detecting and understanding of latent infections in herd/flock health control programmes, though PCR methods for detecting P. multocida in clinical specimen appear increasingly preferred. For establishing the clonality of outbreak strains, we select to discuss macromolecular profiling, serotyping, biotyping, restriction enzyme analysis, ribotyping and multiplex PCR typing. Although P. multocida infections can be rapidly diagnosed with molecular and serological tests, isolation and accurate species identification are central to epidemiological tracing of outbreak strains. Our review brings together comprehensive and essential information that may be adapted for confirming diagnosis and determining the molecular epidemiology of diseases associated with P. multocida.

Use of selamectin for the treatment of psoroptic and sarcoptic mite infestation in rabbits

Selamectin, a novel avermectin compound, was evaluated for its efficacy against naturally occurring infestations of Psoroptes cuniculi and Sarcoptes scabiei. A total of 42 New Zealand rabbits with psoroptic mange and 37 Angora rabbits with sarcoptic mange were used in the present study. On day 0, infested rabbits were treated topically with either selamectin at minimum dose of 6 mg kg(-1) (6-18 mg kg(-1) for New Zealand rabbits, n = 31 and 10-12 mg kg(-1) for Angora rabbits, n = 23) or vehicle only (control groups, n = 11 for New Zealand rabbits, n = 14 for Angora rabbits). The efficacy of selamectin was assessed both clinically and parasitologically by the presence or absence of viable mites. Rabbits were scraped for sarcoptic mites on days 7, 14, 28, 42 and 56 and had otoscopeic and/or microscopic examination for the detection of Psoroptes mites on days 7, 14, 42 and 56. Fisher's exact test was used to assess differences between the vehicle and selamectin treatment in the number of rabbits without mites (cure rates) on each assessment date. It was found that significantly fewer selamectin-treated rabbits had mites detected on skin scrapings (for S. scabiei) or otoscopeic and/or microscopic examination (for P. cuniculi) (P < 0.01) than the vehicle group. Results of the present study suggest that selamectin is effective against naturally infestations of P. cuniculi and S. scabiei in rabbits.