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United States Department of Agriculture

Agricultural Research Service

Research Project: Intervention Strategies to Control and Prevent Enteric Viral Diseases of Poultry

Location: Endemic Poultry Viral Diseases Research Unit

Title: HN gene c-terminal extension of Newcastle disease virus is not the determinant of the enteric tropism

Authors
item Zhao, Wei -
item Hu, Haixia -
item Zsak, Laszlo
item Yu, Qingzhong
item Yang, Zengqi -

Submitted to: Virus Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 11, 2013
Publication Date: August 8, 2013
Repository URL: http://handle.nal.usda.gov/10113/59848
Citation: Zhao, W., Hu, H., Zsak, L., Yu, Q., Yang, Z. 2013. HN gene c-terminal extension of Newcastle disease virus is not the determinant of the enteric tropism. Virus Genes. 47:27-33.

Interpretive Summary: Newcastle disease virus (NDV) can cause serious diseases and significant economic losses to the poultry industry worldwide. The hemagglutinin-neuraminidase (HN) protein of NDV plays an important role in virus virulence and tissue tropism. Many low virulent enteric NDV strains have a larger HN protein (616 amino acids, aa) with additional 39 aa at its C-terminus when compared with that (577 aa) of respirotropic NDV strains. Therefore, it has been suspected that the HN C-terminal extension may contribute to the enteric tropism. In the present study, we generated a recombinant NDV by placing the HN protein C-terminal 39 aa derived from an enterotropic NDV strain into the HN gene of the respirotropic LaSota strain using reverse genetics techniques to assess the role of the HN C-terminal extension in virus tissue tropism. The biological characterization of the recombinant virus showed that the HN C-terminal extension slightly attenuated the virus virulence in embryonated eggs and in day-old chicks when compared to the parental LaSota virus. However, the HN C-terminal extension did not alter virus tissue preference to grow. In infected chickens, the recombinant virus was detected in the tracheal tissue, but not in the intestinal tissue, exhibiting a similar respirotropic tissue preference as its parental LaSota strain. These results demonstrated that the HN protein C-terminal extension of NDV is not the determinant of the virus enteric tropism.

Technical Abstract: The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) plays an important role in virus pathogenicity and tissue tropism. Sequence analysis revealed that the HN gene of many asymptomatic enteric NDV strains encodes a larger open reading frame (616 amino acids, aa) with additional 39 aa at its C-terminus when compared with that (577 aa) of respirotropic NDV strains. Therefore, it has been suspected that the HN C-terminal extension may contribute to the enteric tropism. In the present study, we generated a NDV respirotropic strain LaSota-based recombinant virus with a HN C-terminal extension of 39 aa derived from an enterotropic NDV strain using reverse genetics technology. The biological characterization of the recombinant virus, rLS-HN-ex, showed that the HN C-terminal extension slightly attenuated the virus pathogenicity in embryonated eggs and in day-old chicks when compared to the parental LaSota virus. However, the HN C-terminal extension did not alter virus tissue tropism. In infected chickens, the recombinant virus was detected and re-isolated from the tracheal tissue, but not from the intestinal tissue, exhibiting a similar respirotropic tissue preference as its parental LaSota strain. These results demonstrated that the HN protein C-terminal extension of NDV is not the determinant of the virus enteric tropism.

Last Modified: 12/20/2014
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