Submitted to: Animal Influenza Virus
Publication Type: Book / Chapter
Publication Acceptance Date: 1/15/2014
Publication Date: 6/24/2014
Citation: Miller, P.J., Torchetti, M.K. 2014. Newcastle disease virus detection and differentiation from avian influenza. In: Spackman, E., editor. Animal Influenza Virus: Methods in Molecular Biology. Volume 1161. New York, NY: Humana Press. p. 235-239. Interpretive Summary: Infections of birds with Newcastle disease virus (NDV) can easily be confused with avian influenza virus because the clinical signs of disease are similar and both viruses cause red blood cells to clump together. In addition, sometimes birds can be infected with both viruses at the same time. There are tests that can be performed to distinguish which virus has been isolated from a bird. If you have access to NDV specific antisera a hemagglutination inhibition (HI) test can be performed. This test prevents the clumping of the red blood cells when the serum is added to your unknown virus, if the virus is NDV. If you have the ability to extract RNA from your unknown virus, you can run a real time RT-PCR assay that will detect NDV if it is present in only a few hours. Unfortunately, because most chickens are vaccinated against NDV we cannot use the presence of antibodies in their sera to detect if they are infected or exposed to NDV. This book chapter gives guidance as to how to distinguish if your sample contains NDV if you discover that it does not have AIV.
Technical Abstract: Newcastle disease (ND) is a contagious and often fatal disease that affects over 250 bird species worldwide, and is caused by infection with virulent strains of avian paramyxovirus-1 (APMV-1) of the family Paramyxoviridae, genus Avulavirus. Infections of poultry with virulent strains of APMV-1 (Newcastle disease virus) are reportable to the World Organization for Animal Health (OIE). Vaccination of poultry species is a key measure in the control of ND. Other APMV-1 viruses of low virulence, which are not used as vaccines, are also often isolated from wild bird species. The APMV-1 virus, like avian influenza virus (AIV), is a hemagglutinating virus (HA) and able to agglutinate chicken red blood cells (RBC). Because the clinical presentation of ND can be difficult to distinguish from disease caused by AIV, techniques for differential diagnosis are essential, as well as the ability to detect mixed infections. When an HA positive virus is detected from virus isolation, additional assays can be performed to determine which virus is present. Both antigenic and molecular methods are necessary as some virulent ND viruses from cormorants in the United States (US) after 2002 have lost their ability to hemagglutinate chicken RBC and molecular methods are needed for identification. The available starting material (e.g. live virus from infected allantoic fluid, tissue cell culture medium, or extracted RNA), reagents, and equipment will determine the method used to identify the presence of APMV-1. Hemagglutinating fluid from cell culture supernatants or egg fluids may be further identified by the hemagglutination inhibition (HI) assay or by RT-PCR. Currently available serologic assays (HI, ELISA) are not able to distinguish antibodies due to vaccination from those due to infection. This book chapter gives guidance on how to determine if the sample you thought was AIV is really NDV.