Poultry Disease Research

NON-TECHNICAL SUMMARY: Poultry is Georgia's largest agricultural commodity and diseases negatively affect poultry as a food source and Georgia's economic growth. The purpose of this research is the early detection of diseases affecting live poultry & diseases that affect poultry as a food source and to develop vaccines that combat these diseases.

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APPROACH: 1. A glycoprotein E mammalian expression plasmid will be constructed and used for transfection of LMH cells. Antibiotic resistance will be used to select LMH cells expressing glycoprotein E. 2. Use computer & published sequence analysis to identify primers in P,F, and HN genes specific for END as well as vaccine/lentogenic NDV's. Combine primer sets in a multiplex RT-PCR reaction & optimize reagent concentration & thermalcycler parameters. Determine sensitivity & specificity of primer sets in uniplex & multiplex RT-PCRs. 3. Grow recombinant baculovirus containing the N2 gene. Verify expression of N2 by indirect fluorescent antibody testing and wertern blot. Coat ELISA platew with concentration of purified N2 protein, then examine sensitivity & specificity . 4. Japanese quail will be infected with REV and allowed to reproduce. Examine both generations for antibody & presence of virus in serum, plasma, feather pulp, & oral or cloacal secretions. A 3rd generation will be examined similarly. 5. clostridium-like 16S rDNA sequences will be combined from online data bases & obtained from human & food animal species. Sequences will be searched to identify restriction enzyme recognitionuseful for T-RFLP analysis for distinguishing clostridia from different animal species. T-RFLP will be used to identify profiles unique to animal species from which the fecal sample was collected. 6. Implement the integrated poultry surveillance network. Establish a database of Salmonella strains present in parental flocks in order to quantitate vertical transmision of specified serotypes and pathotypes through the poultry pyramid.
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PROGRESS: 2004/07 TO 2009/06 <BR>
OUTPUTS: 1) Runting/stunting syndrome. A repeatable challenge model was developed which consistently produces 40% weight gain suppression. Novel viruses associated with the syndrome were characterized. A recombinant baculovirus which expresses a novel astrovirus capsid protein was developed as a vaccine candidate and is being evaluated for use as a vaccine. 2) Infectious laryngotracheitis (ILT). A system was developed to delete specific genes from ILT virus. Deletion mutants are being evaluated as vaccine candidates. 3) Avian mycoplasmosis. The protection afforded by Mycoplasma gallisepticum vaccines was evaluated. The relative protection provided by F strain, ts-11, and 6/85 commercial vaccines as well as vaccine candidates K5054 and K2101 was determined. A Mycoplasma gallisepticum isolate from the field to be genetically very similar to a commercial vaccine. This isolate is being evaluated for its ability to transmit vertically from vaccinated breeders to progeny. 4) Infectious bronchitis. The S-1 gene sequence of infectious bronchitis viruses was studied. The S-1 genes from the Massachusetts, Connecticut, Delaware, Georgia, Arkansas serotype vaccines were sequenced and submitted to GenBank. Additionally, multiple coronaviruses from birds were completely genetically sequenced. It was found that recombination of coronaviruses is likely occurring in the field. 5) Clostridial dermatitis. A reproducible model for the disease was developed. The disease was not exacerbated by concomitant immunosuppression. An epidemiological survey was conducted to determine the management and environmental factors associated with the disease on commercial broiler farms. 6) Avian influenza. Low pathogenic avian influenza viruses were evaluated for their pathogenicity in chickens and turkeys. Virus recovery was detected by real time RT-PCR for 11 of 16 viruses in chickens and 8 of 16 viruses in turkeys. Mild clinical signs were seen with only one isolate. <BR>
PARTICIPANTS: Glisson, J.; Garcia, M.; Hofacre, C.; Jackwood, J.; Maurer, J.; Sellers, H.; Zavalla, G.
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IMPACT: 2004/07 TO 2009/06<BR>

This project seeks to provide solutions for the most important disease problems facing the US poultry industry. Important progress has been made toward better control of all of the diseases included within the scope of this project. The pathogenesis and etiology of runting/stunting of broilers has been characterized and potential vaccine candidates developed. Major advances have been contributed toward the control of this disease. Basic research has been performed that is necessary to create a new approach to vaccination for ILT by using gene deletion mutants of ILT virus. A much better understanding has been gained about the use of live Mycoplasma gallisepticum vaccines that helps the poultry industry to better utilize these products in the field. Infectious bronchitis is one of the most difficult poultry viral diseases to control because of the genetic instability of the virus. Important contributions were made in establishing the genetic information required to understand the genetic variability of the virus that has been observed from isolates from the field. Clostridial dermatitis is an important re-emerging disease for which the pathogenesis is poorly understood. This project provided a reproducible model for studying the disease and established the epidemiologic factors associated with the occurrence of the disease in the US broiler industry. Avian influenza virus can be isolated from wild waterfowl in the US. This project established that typical representative waterfowl isolates are not pathogenic in chickens and turkeys.