Progress 07/01/10 to 06/30/13
Outputs
Target Audience: Veterinarians, other poultry health officials and other researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Avian Influenza Outreach The Avian Bioscience Center developed and offered a four day certificate course on Emergency Poultry Disease Response (EPDR). Course development was grant-supported, however, the program has become self-supporting. The four day course has met the sustainability goal by extending beyond the funding period with additional training programs planned for the future. During the course of the program, there have been 53 participants, from 6 continents and from 40 different countries. Two participants from 2012 returned from the program to deal with an emerging highly pathogenic avian influenza (HPAI) outbreak in their home country and immediately implemented material from the program. Course content has evolved from year to year based on pre-course, post-course and alumni assessment of participants and includes a combination of lecture and hands on demonstrations. The training program presented and utilizes the “Delaware model,” which emphasizes close cooperation between government, industry and educational institutions to manage avian influenza outbreaks. Specifically, participants learned about the Delmarva (Delaware (Del), Maryland (Mar), Virginia (Va) poultry industry’s best management practices and technologies related to controlling outbreaks of avian influenza and other catastrophic disease outbreaks. Topics in the course included understanding the biology of influenza virus, the United States Live Bird Market system, surveillance, biosecurity, zoonotic and foreign animal diseases, outbreak response and control, incident command structures, protecting the responder and personal protection, depopulation, disposal and composting, and decontamination. Hands on demonstrations included personal protective equipment and swabbing, foam depopulation, composting, and equipment disinfection. The program is now RACE certified, allowing participants to earn continuing education credits (CEU) suitable for veterinary and/or veterinary technician continuing education requirements. Assessment results for the program have been positive. This certification program represents a long term educational objective and the program has become a self-supporting educational program. How have the results been disseminated to communities of interest? Please see the list of publications. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Avian Influenza Research In the areas of disease pathogenicity and pathogenesis, three studies were performed. Avian influenza (AI) viruses infect numerous avian species, and low pathogenicity (LP) AI viruses of the H7 subtype are typically reported to produce mild or subclinical infections in both wild aquatic birds and domestic poultry. However relatively little work has been done to compare LPAI viruses from different avian species for their ability to cause disease in domestic poultry under the same conditions. In the first study, the potential of low pathogenicity (LP) avian influenza virus (AIV) isolates of wild bird origin to establish infection in commercial turkeys and broiler chickens was studied. Isolates, representing subtypes H5N1, H7N3, H6N2, and H3N6, were recovered in 2005 and 2006 from waterfowl and shorebirds in the Delmarva Peninsula region of the east coast of the United States. The LP AIV isolates were not pathogenic for 2-wk-old meat-type turkeys and broiler chickens. No mortality, clinical signs, or gross lesions were observed following intratracheal and conjunctival sac routes of exposures with 10(6.0) EID50 (embryo infectious dose) per bird. Isolates resulting in an established infection based on virus isolation were: A/mallard/Maryland/1159/ 2006 (H5N1) in the upper respiratory tract of turkeys; A/mallard/Delaware/418/2005 (H7N3) in the upper respiratory and intestinal tracts of turkeys and chickens; and A/shorebird-environment/Delaware/251/2005 (H3N6) in the upper respiratory and intestinal tracts of chickens. Infections were also confirmed by production of AIV-specific serum antibodies detected by hemagglutination inhibition. In study 2, twelve H7 LPAI virus isolates from North America were each evaluated for their comparative pathogenesis in chickens, ducks, and turkeys. All 12 isolates were able to infect all three species at a dose of 106 50% egg infectious doses based on seroconversion, although not all animals seroconverted with each isolate-species combination. The severity of disease varied among isolate and species combinations, but there was a consistent trend for clinical disease to be most severe in turkeys where all 12 isolates induced disease, and mortality was observed in turkeys exposed to 9 of the 12 viruses. Turkeys also shed virus by the oral and cloacal routes at significantly higher titers than either ducks or chickens at numerous time points. Only 3 isolates induced observable clinical disease in ducks and only 6 isolates induced disease in chickens, which was generally very mild and did not result in mortality. Full genome sequence was completed for all 12 isolates and some isolates did have features consistent with adaptation to poultry (e.g. NA stalk deletions), however none of these features correlated with disease severity. The data suggests that turkeys may be more susceptible to clinical disease from the H7 LPAI viruses included in this study than either chickens or ducks. However the severity of disease and degree of virus shed was not clearly correlated with any isolate or group of isolates, but relied on specific species and isolate combinations. In the third study, wild waterfowl, including ducks, represent the classic reservoir for low pathogenicity avian influenza (LPAI) viruses and play a major role in the worldwide dissemination of AIV. AIVs belonging to the hemagglutinin (H) 7 subtype are of epidemiological and economic importance due to their potential to mutate into a highly pathogenic form of the virus. Thus far, however, relatively little work has been conducted on elucidating the host-pathogen interactions of ducks and H7 LPAIVs. In the current study, three H7 LPAIVs isolated from either chicken, duck, or turkey avian species were evaluated for their comparative effect on the transcriptional innate immune response of ducks. Three H7 LPAIV isolates, chicken-origin (A/chicken/Maryland/MinhMa/2004), duck-origin (A/pintail/Minnesota/423/1999), and turkey-origin (A/turkey/Virginia/SEP-67/2002) were used to infect Pekin ducks. At 3 days post-infection, RNA from spleen tissue was used for transcriptional analysis using the Avian Innate Immune Microarray (AIIM) and quantitative real-time RT-PCR (qRT-PCR). Microarray analysis revealed that a core set of 61 genes was differentially regulated in response to all three LPAIVs. Furthermore, we observed 101, 135, and 628 differentially expressed genes unique to infection with the chicken-, duck-, or turkey-origin LPAIV isolates, respectively. qRT-PCR results revealed significant (p<0.05) induction of IL-1β, IL-2, and IFNγ transcription, with the greatest induction observed upon infection with the chicken-origin isolate. Several key innate immune pathways were activated in response to LPAIV infection including the toll-like receptor and RIG-I-like receptor pathways. Pekin ducks elicit a unique innate immune response to different species-of-origin H7 LPAIV isolates. However, twelve identifiable genes and their associated cell signaling pathways (RIG-I, NOD, TLR) are differentially expressed regardless of isolate origin. This core set of genes are critical to the duck immune response to AI. These data provide insight into the potential mechanisms employed by ducks to tolerate AI viral infection. Avian Influenza Surveillance The consistent recovery of low-path AIV from wild birds on the Delmarva peninsula was concerning to the health and susceptibility of broiler chickens raised in the region. Studies were performed to better understand the process of AI virus adaptation from the natural reservoir, a duck, to spillover hosts, commercial poultry. A low path H5N1 AIV isolated a wild mallard duck on Delmarva was passaged in laboratory trials through meat type turkeys, broiler type chickens, quail and domesticated mallard ducks. After 10 successive passages in the various hosts, the genetic diversity of each of the four species adapted virus were analyzed and compared to the parental wild duck origin strain. Utilizing Illumina generated deep sequencing, the genomes were compared to map genetic variation associated with host adaptation. Although the analysis of all viral genomes has not been completed, one notable observation was made in the broiler type chicken adapted LP H5N1 virus. In greater than 50% of the sequence reads spanning the cleavage site of the hemagglutinin (H) gene, an additional basic residue was detected. The pathotype switch from LP to highly pathogenic strains has been linked to the accumulation of basic amino acids at this aforementioned location. Although an increase in pathogenicity was not observed, the broiler adapted virus contained H gene changes which suggest a switch in pathogenicity may be forthcoming. The mixed population of sequence variants was not observed in the parental virus or any of the other host adapted viruses. The results of this research were presented at the 2010 and 2011 annual meetings of the American Association of Avian Pathologists.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Joerger RD, Sartori C, Frye JG, Turpin JB, Schmidt C, McClelland M, Porwollik S. Gene expression analysis of Salmonella enterica Enteritidis Nal(R) and Salmonella enterica Kentucky 3795 exposed to HCI and acetic acid in rich medium. Foodborne Pathog Dis 9(4):331-7. doi: 10.1089/fpd.2011.0984.
- Type:
Journal Articles
Status:
Published
Year Published:
2010
Citation:
Joerger RD, Hanning IB, Ricke SC.Presence of arsenic resistance in Salmonella enterica serovar Kentucky and other serovars isolated from poultry. Avian Diseases 54(4):1178-82
- Type:
Journal Articles
Status:
Published
Year Published:
2010
Citation:
Ladman BS, Driscoll CP, Pope CR, Slemons RD, Gelb J Jr. Potential of low pathogenicity avian influenza viruses of wild bird origin to establish experimental infections in turkeys and chickens. Avian Diseases 54(3): 1091-4.
- Type:
Journal Articles
Status:
Published
Year Published:
2010
Citation:
Spackman E, Gelb J Jr, Preskenis LA, Ladman BS, Pope CR, Pantin-Jackwood MJ, McKinley ET. The pathogenesis of low pathogenicity H7 avian influenza viruses in chickens, ducks and turkeys. Virol J. 7:331. doi: 10.1186/1743-422X-7-331.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Ladman BS, Spackman E, Gelb J Jr. Comparison of pooling eleven or five oropharyngeal swabbings for detecting avian influenza virus by real-time RT-PCR in broiler chickens. Avian Disease 56:227-229.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Maughan MN, Dougherty LS, Preskenis LA, Ladman BS, Gelb J Jr, Spackman EV, Keeler CL Jr. Transcriptional analysis of the innate immune response of ducks to different species-of-origin low pathogenic H& avian influenza viruses. Virology Journal. Virol J. 2013 Mar 23;10:94. doi: 10.1186/1743-422X-10-94.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Wang Y, Ladman BS, Wu C, Gelb J Jr, Golovan S. Comparison of vRNA and cRNA based reporters for detection of influenza replication. Antiviral Res. 2013 Apr;98(1):76-84. doi: 10.1016/j.antiviral.2013.01.008.
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Progress 07/01/10 to 06/30/11
Outputs
OUTPUTS: The University of Delaware Poultry Health System (UDPHS), which consists of two laboratories, is a provisionally approved member of the National Animal Health Laboratory Network (NAHLN). Many hours have been spent keeping the UDPHS in compliance with NAHLN regulations. The NAHLN mandated quality management system has enhanced the validity of our results in the eyes of the non-poultry, avian community as well as the domestic and international poultry industries. During FY2010, the final year of the USDA/Wildlife Services funded avian influenza virus (AIV) surveillance of wild birds, approximately 700 samples were tested following National Veterinary Services Laboratory (NVSL) protocols. Nearly 20 non-H5 and non-H7 wild bird origin AIV isolations were made. In addition, three avian paramyxovirus (APMV) isolates were identified. An experiment was conducted to assess the pathogenicity of these wild bird origin APMVs in commercial poultry. APMVs do represent a real health risk to the poultry industry. However, the risks can likely be mitigated by normal vaccination for Newcastle Diseasae virus and sound biosecurity procedures. The results of this research were presented in poster form at the 2011 meeting of the American Association of Avian Pathologists. PARTICIPANTS: As an instructor in the Emergency Poultry Disease Response Certificate Course, I lectured and led discussions related to AIV surveillance efforts. The course was attended by a diverse group of international animal health professionals. Presentations displayed approaches taken on Delmarva and helped attendees to determine what actions can be taken to address their animal health issues. The hope is that EPDR graduates share their knowledge with colleagues upon returning home. One graduate student has graduated from the lab with a Master's of Science degree in Animal Science in FY2010. Her project helped to better understand the genetic profile of avian infectious bursal disease viruses found on Delmarva poultry farms. Data generated from this project was integral in obtaining industry supported funding for future research. TARGET AUDIENCES: Domestic and International Poultry Industry; State Veterinarian. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A novel strain of avian infectious bronchitis virus (IBV) was identified during normal surveillance activities. Isolate DMV/1639/11 was found to be identical to an Pennsylvania isolate which was molecularly characterized a few months prior. Reported by clinicians as nephropathogenic IBV, the tropism for kidney was experimentally confirmed in meat type chickens. The efficacy of currently available, commercial IBV vaccines has been evaluated under controlled conditions using experimental and commercially reared birds. Results of these trials are pending however, it appears that vaccination does not present nephropathogenic IBV associated kidney pathology. Our findings will be presented at the Delmarva Poultry Industry, Inc. (DPI)-sponsored 46th National Meeting on Poultry Health and Processing in Ocean City, Maryland. Infectious layrngotracheitis virus (ILTV) continues to affect commercial poultry in spite of vaccination. Adverse vaccine reactions as well as the efficacy of currently available vaccine have led to the search for new vaccine choices. We have adapted multiple strains of ILTV to grow in sub-optimal temperatures. Trials have been performed to both evaluate attenuation as well as the antigenicity of the ILTV vaccine candidates. At least two strains appear to be attenuated. We are still evaluating their potential for use as vaccines.
Publications
- Spackman, Erica, Jack Gelb, Lauren Preskenis, Brian Ladman, Conrad Pope, Mary Pantin-Jackwood, and Enid McKinley (2010). The pathogenesis of low pathogenicity H7 avian influenza viruses in chickens, ducks and turkeys. Virology Journal 7:331 doi:10.1186/1743-422X-7-331.
- Ladman, B., E. Spackman, and J. Gelb, Jr. (2011). Comparison of Pooling Eleven or Five Oropharyngeal Swabbings for Detecting Avian Influenza Virus by Real-Time RT-PCR in Broiler Chickens. Avian Diseases. Accepted for publication August 21, 2011.
- Gelb, J., D. Jackwood, E. Mundt, C. Pope, R. Hein, G. Slacum, J. Harris, B. Ladman, P. Lynch, D. Bautista, J. Ruano, and M. Troeber (2011). Characterization of Infectious Bursal Disease Viruses Isolated in 2007 from Delmarva Commercial Broiler Chickens. Avian Diseases. Pending August 19, 2011.
- Farkas, T., B. Fey, E. Hargitt III, M. Parcells, B. Ladman, M. Murgia, Y. Saif. (2011). Detection of novel picornaviruses in chickens and turkeys. Journal of General Virology. Submitted August 19, 2011.
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