Brief Summary of Minutes of Annual Meeting

Objective I: Identify reservoirs of infectious respiratory disease agents in wild birds and poultry. 1. Isolation and characterization of avian influenza viruses (AIV) from wild birds, which include hunter-killed or nesting waterfowl and shorebirds, starlings, and raptors, were accomplished. The enormous data obtained from different states (AL, DE, GA, MN, OH) are being shared. 2. Surveillance activities on the Delmarva Peninsula have yielded infectious laryngotracheitis (LT) virus and infectious bronchitis virus isolates from commercial broiler chickens. 3. In DE, LT incidence down in 2009 due to widespread vaccination. Severity of LT clinical signs and lesions are mild to moderate, very similar to that seen in adverse CEO vaccine reactions. 4. GA isolated and characterized current pathogenic respiratory viruses, bacteria, and mycoplasmas circulating within the poultry industry in Georgia. Identified at least 41 MG genotypes that are distinguishable from live vaccines and unique to individual countries or regions. Objective II. Develop improved diagnostic capabilities including real time PCR as well as other rapid on-farm tests for economically important respiratory diseases. 1. AL developed a rapid, accurate, and economical method for ILTV detection using a molecular technique Loop-mediated isothermal amplification (LAMP). The LAMP could detect viral DNA directly from the tracheae of vaccine virus infected birds as well as ILTV plaques from embryonic eggs. 2. CT designed nine pairs of neuramidinase (NA) subtype-specific primers using Primer Hunter design tool and successfully used in real time RT-PCR with four primer-pool reactions to differentiate nine NA subtypes of AIV. 3. GA developed an indirect N1 and N2 ELISAs which were proven to be effective and rapid assay to identify exposure to challenge virus during a DIVA vaccination strategy. In addition, a speciesindependent competitive ELISA (cELISA) for the detection of H6, H7, H9 antibodies in several species was developed. 4. MN developed degenerate primer set for full-length amplification of four genes of influenza A viruses in a single reaction. 5. OH established the chloroform-Mag MAXTM method of viral RNA extraction followed by RRT-PCR which can be used as rapid and sensitive test to determine the titer of the viral RNA. Using this method, it was found that different commercial vaccines contain varied antigen contents. 6. SEPRL (USDA) developed two real time RT-PCR assays that allow the differentiation of North American H1N1 from pandemic H1N1. In addition, the current H7 RRT-PCR was improved to detect a broader range of H7 viruses that are found in Western hemisphere. 7. SEPRL demonstrated that NDV Matrix assay failed to detect a virulent NDV. If genotype VII virus was found in North America this assay could be used in the NALHN laboratories. Objective III. Investigate the pathogenesis and polymicrobial interactions of specific infectious agents associated with poultry respiratory diseases (this includes interactions with underlying immunosuppressive agents). 1. DE isolated 5038 IBDV isolate from commercial broiler chickens. Although unique based on VP2 sequencing and monoclonal antibody testing, may not be capable of breaking through maternal immunity in a laboratory designed trial may not be able to break through in real world progeny challenges. 2. GA identifed that temperature plays a pivotal role in the survivability of LPAI virus in feces and in contact with litter. GA also identified that a percentage of chickens receiving recombinant or TCO vaccines carry a significant amount of virulent ILTV in the trachea in the absence of clinical signs after being challenged with virulent ILTV. 3. Comparative genomic analysis of IBV indicates that the replicase protein in addition to the already recognized spike gene of coronaviuses plays a key role in pathogenicity. GA have identified regions in the replicase that likely effects cleavage and assembly of the enzyme. 4. OH identified amino acids contributing to antigenic drift in the Del-E infectious bursal disease virus. The short term implication this has for the poultry industry is that diagnostic assays designed to identify the 254 and 222 amino acids will discover viruses that have antigenically important mutations. 5. OH showed that two virulent infectious bursal disease viruses (vvIBDV) from California are identical and meet all the characteristics of a vvIBDV. Because they have the potential to spread rapidly and cause high mortality in chickens, the impact of these viruses on the U.S. broiler and layer industries could be considerable. 6. OH detected low pathogenic influenza viruses in albumin of eggs using real time RT-PCR and virus isolation in embryonated chicken eggs. Swabs from egg shells were also found positive by RRT-PCR. Objective IV. Develop new prevention and control strategies for poultry respiratory diseases. 1. AL developed two recombinant vaccines against H1N1 AIV (one DNA and the other in yeast) and found to induce a measurable immune response in young chickens. The DNA vaccine was given by injection and the yeast vaccine in the drinking water. 2. CT tested in ovo vaccination of recombinant DNA plasmid containing IBV spike gene with interferon-a which showed over 98% of protection rate against M41 field isolate challenge. 3. DE developed a second generation escape resistant RNAi constructs against avian influenza virus and found that avian-specific RNAi constructs against avian influenza virus did not increase the efficiency of RNAi inhibition. 4. IN demonstrated that IBDV large segment gene-based DNA can elicit specific immune response and provide protection of broiler chickens with maternally derived antibody against infection challenge. 5. OH developed NA- and NS-based DIVA vaccine strains using traditional reassortment as well as reverse genetics methods against H3N2 influenza in turkeys. The reassortant DIVA vaccines significantly reduced challenge virus shedding in the oviduct of breeder turkeys as well as trachea and cloaca of both young and old breeder turkeys, suggesting that proper vaccination could effectively prevent egg production drop and potential viral contamination of eggs in infected turkeys. 6. SERPL demonstrated that H7 AI vaccine may not protect against intercontinental H7 field viruses and vaccine may need to be from the same H7 lineage as field viruses to provide protection. In addition, turkeys vaccinated with commercial H1N1 vaccine have a low chance of being protected against swine-origin H1N1 infection. 7. SEPRL developed a model system for NDV vaccination which mimic egg production losses seen in Asia and Mexico in vaccinated poultry were developed and this system will allow the comparison of vaccines.