The major outer membrane protein (OmpH) of Pasteurella multocida X-73 was purified by selective extraction with detergents, followed by size exclusion chromatography. The planar lipid bilayer assay showed that OmpH has pore-forming function. The average single channel conductance in 1.0 M KCl was 0.62 nS. The gene (ompH) encoding OmpH has been isolated and sequenced by construction of a genomic library and PCR techniques. The coding region of this gene is 1,059 bp long. The predicted primary protein is composed of 353 amino acids, with a 20-amino-acid signal peptide. The mature protein is composed of 333 amino acids with a molecular mass of 36.665 kDa. The ompH gene encoding mature protein has been expressed in Escherichia coli by using a regulatable expression system. The ompH gene was distributed among 15 P. multocida serotypes and strain CU. Protection studies showed that OmpH was able to induce homologous protection in chickens. These findings demonstrate that OmpH is a protective outer membrane porin of strain X-73 and is conserved among P. multocida somatic serotypes.
Four avian heterophil antimicrobial cationic peptides (Chicken Heterophil Peptides 1 and 2, and Turkey Heterophil Peptides 1 and 3) were evaluated for in vitro microbicidal activity against selected avian pathogens and human pathogens which are harbored by birds. At concentrations of 16-2 micrograms/ml, all four avian peptides effected a greater than 90% reduction in the survival of Candida albicans, Salmonella enteriditis, and Campylobacter jejuni. None of the peptides, including the known antimicrobial peptide protamine (used as a positive control), were able to reduce the survival of Pasteurella multocida by 90% at the maximum peptide concentration (16 micrograms/ml) tested. At 16 micrograms/ml, the turkey peptide THP3 did not effect a 90% reduction in survival of Bordetella avium, Escherichia coli, or Salmonella typhimurium, while all of the other peptides tested were effective at this concentration or less. This peptide, THP3, does not share the same homologous amino acid sequence shared by the other three peptides. Under our experimental conditions, none of the peptides neutralized Infectious Bronchitis Virus, an enveloped coronavirus of chickens.
During 2001, a mild infectious laryngotracheitis virus (ILTV) infection occurred in broiler flocks in the southeastern United States. Clinical signs included mild tracheitis, swollen sinuses, and conjunctivitis, with no increased mortality and minimal serologic response. Infrequent intranuclear inclusion bodies with or without syncytial cell formation were observed in eyelid, trachea, and larynx and in the chorioallantoic membrane of infected embryos. Immunohistochemistry and a nested infectious laryngotracheitis polymerase chain reaction (ILT PCR) were utilized to confirm the presence of ILTV nucleic acid in fixed tissues. In addition, 2-wk-old specific-pathogen-free (SPF) birds inoculated with field material exhibited the mild signs observed in broilers in the field. Tracheal swabs and tissues taken from these SPF birds were also positive by nested ILT PCR. Restriction fragment length polymorphism analysis of ILT PCR products indicated that ILT virus associated with mild respiratory disease in the southeast is related to the chicken embryo origin vaccine type strains.
Abstract. Heterophil functio n was eva lua ted in 16 health y chickens and in 46 chickens with experime nta lly induced sta phylococcal tenosynovit is. In paired blood sa mples, heterophils from chicke ns with tenosynovit is had a significant increase in ad he rence, chemo tax is, pha gocyto sis, and bact erial killin g of S taphylococcus aureus compared to heterophils from healthy chickens. Th e percent adh erence of heterophils to nylon fiber columns increased significantly from a 78.4 % mean ± 6.6% standa rd deviati on to 87 .6% ± 3.2% aft er induct ion of sta phylococcal ten osynovitis. Heteroph il movem ent followi ng in vitro expos ure to saline or endo toxi n was increased in chickens with tenosy novitis; 3 ± I heterophil s/ 0.25 rnrn-to 10 ± 6 heteroph ils/ 0. 25 mrn ? and 136 ± 29 heterophils/0. 25 mrn -to 340 ± 74 het erophils/ 0. 25 mm -, respe ctively. Endotoxin-acti vated seru m was che moa tt rac tive for heterophil s from all chickens. Flow cyto me try was used to define th e heterophil population on light scatte r histogram s, eva luate ind ivid ua l cell phagocytosis of latex bead s, and qu antitat e the number of bead s ph agocytosed per heterophil. Wh en inc ubated with increase d num bers of beads , only heterophils from chickens with ten osynovitis phagocytosed higher numbers of beads . At heterophil to bead rat ios of I : 10, the percent age of heterophils that pha gocytosed bead s increased from baselin e values of 37.8% ± 9.0% to postin fecti on va lues of67.3% ± 7.5%. Us ing I : 20 heteroph il to bean rati os, heteroph il phago cytosis increased from 38 .7% ± 9.9% to pos t-infection va lues of79.8% ± 7.3%. Heterophils fro m all chickens were able to phagocytose and kill log phase sta phy lococca l bacteria . After phagocytosis, the heterophils from chicke ns with staphylococc al tenosyn oviti s rapidl y decrea sed the number o f viable bacterial colony forming-units per millil iter by approximately one log. Circulating heterophil s from chickens with ex perime ntally induced sta phylococcal ten osynoviti s th erefore appear to have increased function al ca pa bilities in thi s bacterial inflam matory disease.
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