New Test May Differentiate Between Poultry Vaccinated Against or Infected with Avian Flu
Feb 18, 2005 - 4:34:38 PM

Avian influenza (AI), a viral disease of poultry, causes a wide range of diseases affecting multiple organs and often resulting in death. In recent years, new strains of the virus have continued to emerge and cross over from the wild bird reservoir to domestic poultry. A new diagnostic test monitoring antibody response to the NS1 virus protein may allow for differentiation between poultry vaccinated or infected with avian influenza say researchers from Georgia.

"Over the last decade, AI viruses circulating in live-bird markets have provided a secondary reservoir from which influenza viruses have crossed over to infect commercial chicken and turkey operations," say the researchers.

A vaccine incorporating the inactivated whole-virus has been used in an attempt to prevent AI infection. While these traditional vaccines can protect against clinical infection and death, they can interfere with surveillance programs. Vaccination produces the same antibodies as an actual AI infection, and can commonly cause false positives with traditional diagnostic tests.

In the study, the researchers designated the NS1 virus protein, typically found in large amounts in virus-infected cells but not the virus itself, as a potential differential marker. They monitored both infected and vaccinated poultry for antibodies reactive to NS1. While live virus infection induced high levels of the NS1 antibody, commercial vaccines induced little or no antibody response.

"These results demonstrate the potential benefit of a simple, specific enzyme-linked immunosorbent assay (ELISA) for anti-NS1 antibodies that may have diagnostic value for the poultry industries," say the researchers.

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