Pathological, epidemiological, etiological, and immunological aspects of viral diseases affecting commercial poultry and other economically important domestic animal species are a focus of research at the Auburn University College of Veterinary Medicine. Here investigators seek to understand the biology of infectious diseases and develop novel approaches to treat them. The following are a few examples of such research; for more, visit www.vetmed.auburn.edu.
Newcastle Disease Virus
The Hauck lab investigates how Newcastle disease viruses (NDVs) adapt to chickens as hosts. Newcastle disease virus has a wide range of hosts, and wild birds are NDV reservoirs that may pose a risk to domestic poultry. However, NDV strains circulating in wild birds are usually different from NDV strains causing disease in poultry. Here, NDV isolates from several wild duck species were serially passaged in chicken embryos. The genomes of original and passaged isolates were sequenced by use of an improved protocol developed in the Kyriakis lab. Preliminary results show that, while single nucleotide polymorphisms were distributed evenly across the genome, missense mutations were concentrated in a few genes, including the hemagglutinin-neuraminidase gene, the product of which is responsible for viral attachment to host cells. Transcriptomic analysis of chicken embryo lungs showed differences between wild type and passaged isolates. Results will enable assessment of the risk that strains from wild birds pose to domestic poultry.
Avian Influenza
Avian influenza, a highly contagious viral disease of wild and domesticated birds, is a major threat to animal and public health and the economy. Avian influenza (AI) viruses can be highly pathogenic (HP) or of low pathogenicity (LP). Low-pathogenic AIV infections result in mild disease, while HPAI infections can lead to the death of entire flocks of birds within 48 hours. In recent years, HPAI viruses have been circulating in wild birds in North America, occasionally spilling over to domesticated birds, affecting over 100 million poultry and resulting in tens of millions of dollars in economic losses. The Criado and Kyriakis teams are working to advance understanding of the pathogenesis, ecology, and evolution of AI viruses through both in vitro and in vivo approaches. They are also studying immune responses following infection or vaccination and testing vaccines that could offer better, broader protection against infection.
Mapping of missense mutations comparing the first and tenth passage in chicken embryos of NDV isolates from wild ducks. Rows are isolates with genomic regions color coded along the x-axis.
Citation: American Journal of Veterinary Research 85, 12; 10.2460/ajvr.24.10.0292
Infectious Bronchitis Coronavirus Vaccine Recombinants and Vaccine Subpopulations
Research in the Toro and van Santen labs focuses on understanding how worldwide use of infectious bronchitis coronavirus live-attenuated vaccines has aggravated and perpetuated infectious bronchitis virus infections in the poultry industry. Mechanisms behind the success of this coronavirus follow Darwin’s Natural Selection principle, ie, increased genetic and phenotypic diversity from mutations and recombination events followed by selection allowing quick adaptation of the virus population. Research also demonstrated that emerging vaccine subpopulations as well as vaccine recombinant viruses are pathogenic. Moreover, even limited phenotypic changes in the viral spike allow immune escape, as demonstrated by sequencing of viruses obtained from outbreaks of disease in vaccinated flocks. Limited protection conferred by the homologous parental vaccine was also shown experimentally. Available evidence leads to the conclusion that attenuated vaccines should be replaced by alternative technology vaccines if the disease is to be controlled more effectively. (For references, contact Dr. Haroldo Toro.)
