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United States Department of Agriculture

Agricultural Research Service

Research Project: EPIDEMIOLOGY, PATHOGENESIS, AND COUNTERMEASURES TO PREVENT AND CONTROL AVIAN METAPNEUMOVIRUS INFECTION Title: Generation and biological assessment of recombinant avian metapneumovirus subgroup C (aMPV-C) viruses containing different length of the G gene.

Authors
item Yu, Qingzhong
item Estevez, Carlos
item Song, Minxun -
item Kapczynski, Darrell
item Zsak, Laszlo

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2009
Publication Date: November 3, 2009
Citation: Yu, Q., Estevez, C., Song, M., Kapczynski, D.R., Zsak, L. 2010. Generation and biological assessment of recombinant avian metapneumovirus subgroup C (aMPV-C) viruses containing different length of the G gene. Virus Research. 147:182-188.

Interpretive Summary: Avian metapneumovirus is an economically important pathogen of turkeys with a worldwide distribution. The glycoprotein (G) of the virus is believed to play an import role in initiating virus infection and stimulating host immune response. It has been shown that the length of the G gene varies among different avian metapneumovirus subtype C isolates. However, its biological significance in virus growth, virulence, and immunity is unknown. We developed a reverse genetics system for the virus and generated two Colorado (CO) strain-based recombinant viruses containing either the full-length G gene or a truncated G gene of the CO strain. The biological properties of these two recombinant G variants were assessed in Vero cells and in specific-pathogen-free turkeys. The results demonstrated that the large portion of the extracellular domain of the viral attachment protein is not essential for virus viability in cell cultures and in turkeys, but may play a role in enhancing virus attachment specificity and immunity in a natural host.

Technical Abstract: Genetic variation in length of the glycoprotein (G) gene among different avian metapneumovirus subgroup C (aMPV-C) isolates has been reported. However, its biological significance in virus replication, pathogenicity and immunity is unknown. In this study, we developed a reverse genetics system for aMPV-C and generated two Colorado (CO) strain-based recombinant viruses containing either the full-length G gene derived from a Canadian goose isolate or a C-terminally truncated G gene of the CO strain. The truncated short G (sG) gene encoded 252 amino acids (aa), which is 333 aa smaller than the full-length G (585 aa). The biological properties of these two recombinant G variants were assessed in Vero cells and in specific pathogen free (SPF) turkeys. In Vero cells, the short G variant displayed a similar level of growth dynamics and virus titers as the parental aMPV-CO strain, whereas the full-length G variant grew slower than the sG variant during the first 72 hours post-infection. Both of the G variants induced typical cytopathic effects (CPE) that were indistinguishable from those seen with the parental aMPV-CO infection. In SPF turkeys, both of the G variants attenuated and caused little or no disease signs, but the full-length G variant appeared more readily grown in tracheal tissue than the sG variant during the first 5 days post-infection. Both G variants were immunogenic and induced a slightly different level of antibody responses. These results demonstrated that the large portion (333 aa) of the extracellular domain of the viral attachment protein is not essential for virus viability in vitro and in vivo, but may play a role in enhancing virus attachment specificity and immunity in a natural host.

Last Modified: 11/28/2014
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