Title: Pandemic H1N1 influenza virus in Chilean commercial turkeys with genetic and serologic comparisons to U.S. H1N1 avian influenza vaccine isolates Authors
|Gonder, Eric -|
|Tilley, Becky -|
|Hernandez, Andres -|
|Hodgson, Jorge -|
|Wojcinski, Helen -|
|Jiang, Hai Jun -|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 24, 2011
Publication Date: December 7, 2011
Citation: Kapczynski, D.R., Gonder, E., Tilley, B., Hernandez, A., Hodgson, J., Wojcinski, H., Jiang, H., Suarez, D.L. 2011. Pandemic H1N1 influenza virus in Chilean commercial turkeys with genetic and serologic comparisons to U.S. H1N1 avian influenza vaccine isolates. Avian Diseases. 55(4):633-41. Interpretive Summary: Recently, the 2009 human pandemic H1N1 influenza virus was identified in turkey breeders in Chile, Canada and the U.S. resulting in infection and production losses. In these studies genetic and serologic relatedness was determined between avian influenza turkey vaccine isolates and the recent human pandemic H1N1 virus. Genetic analysis demonstrated greater than ninety percent similarity in hemagglutinin gene sequences between avian and human H1N1 viruses. In contrast, minimal cross reaction was observed between serum from vaccinated turkeys against the human H1N1 virus. Taken together, the current turkey H1N1 vaccines may have limited cross protection against the human pandemic H1N1 virus.
Technical Abstract: Beginning in April 2009, a novel H1N1 influenza virus has caused acute respiratory disease in humans, first in Mexico and then spreading around the world. The resulting pandemic influenza A H1N1 2009 (pH1N1) virus was isolated in swine in Canada in June, 2009, and later in turkey breeders in Chile, Canada, and the U.S. The pH1N1 virus consists of gene segments of avian, human and swine influenza origin and raises the potential for infection in poultry following exposure to infected humans or swine. In the U.S., turkeys and swine may be reared together in close proximity and are typically vaccinated against field isolates of avian influenza (AI), including the H1N1 subtype. In these studies, we examine the clinical events following the initial outbreak of pH1N1 in turkeys, as well as determine the relatedness of the hemagglutinin (HA) gene segments from the pH1N1 to two H1N1 AI isolates used as inactivated vaccines in commercial turkeys. Overall, infection of breeder turkey hens with pH1N1 resulted in > 50 % reduction of egg production over a 3-4 week time period. Genetic analysis indicates one H1N1 AI vaccine isolate (A/turkey/North Carolina/17026/1988) contained approximately 92 % nucleotide sequence similarity to the pH1N1 virus (A/Mexico/4109/2009), whereas the more recent AI vaccine isolate (A/turkey/North Carolina/00573/2005) contained 75.9% similarity. Comparison of amino acids found at antigenic sites of the HA protein indicate conserved epitopes at the Sa site, however, major differences were found at the Ca2 site between pH1N1 and A/turkey/North Caroline/127026/1988. Serum samples from two flocks of turkeys vaccinated with the H1N1 AI viruses were taken over a 21 week period in which the birds received 3 subcutaneous vaccinations with a trivalent autogenous vaccine, containing the two H1N1 isolates and a recent H3N2 triple-reassortant AI virus (A/turkey/North Carolina/16108/2003). Hemagglutinin-inhibition (HI) tests were conducted with sera against the homologous AI vaccine isolates as well as the pH1N1 virus to determine if protection would be conferred using the AI vaccine isolates. HI results indicate positive reactivity (HI titer >4 log2) against the vaccine viruses over the course of study. However, limited cross reactivity to the 2009 pH1N1 virus was observed, with positive titers in a limited number of birds (6 out of 20) beginning only after a third vaccination. Taken together these results demonstrate turkeys vaccinated with these would likely not be protected against pH1N1, or would require multiple applications. Thus, current vaccines used in turkey breeders against circulating H1N1 viruses, including the pH1N1, virus should be updated and tested to ensure adequate protection for field exposure.