M E S '9 8 - University of Georgia College of Veterinary Medicine

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8Avian MycoplasmosisThe avian mycoplasmas,Mycoplasma gallisepticum(MG) and Mycoplasma.synoviae (MS) occur as eggtransmittedinfections causingrespiratory, joint, and tendondisease in chickens andturkeys. The objectives of thisstudy were to improve detectionand control measures foravian mycoplasma infection,to study pathogenesis, and todetermine the incidence ofavian mycoplasmas by DNA“fingerprinting.” A polymerasechain reaction (PCR)with random primers(RAPD), developed for rapididentification of specificstrains of MG and other avianmycoplasmas is now routinelyused to identify (fingerprint)specific strains andidentify sources of infection.A library of avian mycoplasmaisolates containing severalDr. Susan Sanchez perpares an ELISA test tohundred isolates has provento be very useful in studyingdetect Pasteurella multocida.strain variation. In addition,PCR primers that detect allknown mycoplasmas, followed by cutting thePCR product with specific enzymes, were utilizedto identify specific strains of MG. MGstrains could be categorized into at least sixgroups by this method. This may provide amethod of “fingerprinting” that would notrequire prior isolation of the organism, whichis often very difficult and might take up tothree weeks.MG vaccine strain ts-11, previouslyshown by us to be effective in multiple agecommercial egg operations for MG control anderadication, has been studied in broiler breeders.This strain was very effective in the field,and measurable protection continued for thelife of the flock. MG, which is pathogenic forchickens and turkeys, is widespread in wildhouse finches and now seems to be on thedecline. Few new cases were identified. Amodel for consistent reproduction of clinicalsynovitis with field strains of MS was developed.This method will prove useful in studiesevaluating antibiotic medication and/or vaccination.In collaboration with Dr. DusanBencina at the University of Ljubljana inSlovenia, the hemagglutinin (HA) of MS wasidentified as a virulence factor. HA positiveclones were pathogenic, whereas HA negativestrains were not. These results improve ourability to detect and control MG and othermycoplasmas in commercial poultry.Stanley H. Kleven, Willie D. Hall, MarcusHead, Kathy Turner, and Victoria Leitingskleven@arches.uga.eduNeuraminidase is a Conserved Antigen ofPasteurella multocida“Sometimes there breaks out in the poultry-yarda disastrous disease, commonlyknown as chicken cholera. The animal whichis prey to this infection is without strength,trembles and has drooping wings.” LouisPasteur spoke these words in 1880 when herevealed his fowl cholera vaccine to the ParisAcademy of Sciences. Pasteur, now known asthe father of modern microbiology, developedthe first attenuated-live vaccine effectiveagainst infection. Live vaccine strains are stillused today to prevent fowl cholera. However,the available live vaccine strains are often toopathogenic for use in chickens, and killed vaccinesinduce protection only against closelyrelated strains of Pasteurella multocida, thebacterium responsible for the disease. We proposeto create a recombinant vaccine that willinduce protection against all P. multocidastrains. We have cloned and sequenced a genepresent in all strains of P. multocida.Furthermore, we have protected chickens fromfowl cholera using recombinant protein fromthis gene. The long-term goal of our researchis to create an effective broadly protective vaccineagainst fowl cholera that can be inexpensivelyused by Georgia poultry producers.Margie D. Leeleem@calc.vet.uga.eduThe Distribution of Virulence Specific-Genesamong Avian Escherichia coli IsolatesAlthough usually commensal residents inmammals and birds, a small percentage ofEscherichia coli isolates can cause disease intheir hosts. Virulence of any microbe is dependenton the organism’s genetics. We haveexamined the distribution of specific virulencegenes among avian E. coli encountered innorthern Georgia. Genes encoding forhemolysins and toxins were absent in avian E.coli as determined from either polymerasechain reaction (PCR) or Southern blots. Othergenes, such as the capsule gene kps and sialicacid-binding lectin sfa, are present in avian E.coli but at a low frequency. Emphasis has beenplaced on looking at the distribution of P-fimbrialgenes among avian E. coli. We lookedspecifically at the adhesin protein of the P-pili,PapG. This protein determines specificity ofdisaccharides recognized by the pili. Inuropathogenic E. coli, there are three PapGalleles, PapG J96 , PapG Ia , and PrsG, that recognizethree different galactosyl disaccharidespresent on the glyolipids of red blood cells.The PapG allele, PapG Ia, is the only adhesinthat has been identified in avian E. coli byeither PCR or Southern blot. This gene waspresent in 25% of the E. coli isolatesexamined.
Hemolysin is one type of virulence factorthat assists in the pathogenesis of E. coli.Currently, hemolytic activity in E. coli hasbeen attributed to one of two alpha hemolysingenes found in either uropathogenic of enterohemorrhagicE. coli. Hemolytic avian E. coliisolates, however, lack both these E. colihemolysin genes. A “new” E. coli gene, hylE,was identified which lacked the conservedamino acid sequence and accessory genescommon to alpha hemolysin. The hlyE genewas found to map at position on the E. colichromosome where virulence genes are commonlyfound in uropathogenic E. coli. Incloning another E. coli hemolysin gene, an E.coli gene was identified that was similar to aSalmonella virulence gene. We are currentlyinvestigating the distribution of this “new”gene among E. coli pathogenic for poultry.Characterization of these virulence genes willassist in our development of probes and crossprotectivevaccines against avian E. coli.John J. Maurerjmaurer@arches.uga.eduInvestigation of Hatchery DisinfectantEfficacy and Effect on Broiler ProductionHatchery sanitation has a significantimpact on chick quality. The proper use of disinfectantsis essential. A disinfectant with greatpromise as a hatchery sanitizer due to its lowcost, efficacy, and low level of toxicity ishydrogen peroxide. Aerosol bacterial counts,egg moisture loss, hatchability, chick quality,and broiler productivity were measured in eggsexposed to hydrogen peroxide fogging andcompared with eggs not exposed to disinfectantduring the incubation period. The efficacyof hydrogen peroxide was also evaluated in thepresence of severe challenge withStaphylococcus aureus contaminated eggs.There was a significant reduction in aerosolbacterial counts within the hatcher when incubatorswere fogged with 3% hydrogen peroxidewhen compared with water-foggedmachines, even in the face of high bacterialchallenge. Eggs exposed to hydrogen peroxidelost a significantly greater amount of moistureduring incubation, but hatchability was notaffected. The use of hydrogen peroxide as ahatchery sanitizer did not affect broiler livability,body weight, or feed conversion but didreduce the incidence of retained yolk sacs in42-day old chickens.Jean E. Sander and Jeanna L. Wilsonjsander@arches.uga.eduIncorporation of Computer-AssistedLearning in Poultry Disease TrainingThe poultry industry in the United Statesis a $40 billion industry, which requires theattention of qualified experts in the field ofpoultry health. An explosion of knowledge isoccurring in veterinary and agricultural sciences.The study of poultry health is highlyspecialized with a few select students enteringthe field. Because the majority of students leanin other directions, many veterinary and agriculturalcurriculums are unable to maintainpoultry health courses. A computerized autotutoriallearning system for the study of poultrydiseases is being developed to fill this educationalvoid. The main objective of this computerprogram is to support the teaching ofanatomy and pathology of different poultryspecies. The disease topics are presented byorgan system and etiology. Basic informationsuch as a glossary, detailed postmortem directions,description of the types of poultry, andinformation on husbandry practices such asbiosecurity is offered to the student to accommodateevery level of knowledge. The formatof the program uses the Internet throughNetscape with only local use allowed. Linksare provided within the program to allow thestudent to access a selected topic for study, orthe student can proceed through the programfrom beginning to end. Images are incorporatedin the text to allow the student to see thelesions associated with each disease.Jean E. Sanderjsander@arches.uga.eduInvestigation of Natural Disease Outbreaksand Field Trial StudiesRespiratory diseasewas investigated in onebroiler operation. Viralserology, isolation, andpolymerase chain reaction(PCR) were used to identifythe primary agent as infectiousbronchitis. Secondarybacterial infection withBordetella avium,Escherichia coli, andOrnithobacteriumrhinotracheale (ORT) wasconfirmed by bacterial cultureof tracheal swabs.Modification of the vaccinationprogram helped toalleviate the problem.Aspergillus fumigatuswas isolated from youngchicks with early mortalityand respiratory problems.Recommendations from ourclinical veterinarians helpedthe integrator to bring theproblem under control.Hemagglutination-inhibition(HI) serology, virusisolation, and PCR testsrevealed that Arkansas 99strain of infectious bronchitisvirus was the cause of aDr. Jean Sander performs a preliminary examinationof day-old chickens prior to microbiological tests.9
Page 3 and 4: VM E S ‘98Veterinary Medical Expe
Page 7 and 8: DNA VaccinesEver since Dr. Edward J
Page 9: Differential Diagnosis of Infectiou
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Page 15 and 16: Cattle and Other RuminantsCattle, s
Page 17 and 18: The Use of in situ Hybridization to
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Page 21 and 22: WildlifeGeorgia’s wildlife habita
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Page 27 and 28: Research Contracts and GrantsAllen,
Page 29 and 30: Administrators and AdvisorsThe Univ
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Page 33 and 34: Selected PublicationsAllen, S.W., C
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M E S '9 8 - University of Georgia College of Veterinary Medicine

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