Limits...
The contribution of PA-X to the virulence of pandemic 2009 H1N1 and highly pathogenic H5N1 avian influenza viruses.

Gao H, Sun Y, Hu J, Qi L, Wang J, Xiong X, Wang Y, He Q, Lin Y, Kong W, Seng LG, Sun H, Pu J, Chang KC, Liu X, Liu J - Sci Rep (2015)

Bottom Line: In this study, we report on the pathogenicity and pathological effects of PA-X deficient 2009 pandemic H1N1 (pH1N1) and highly pathogenic avian influenza H5N1 viruses.Loss of PA-X was also accompanied by accelerated nuclear accumulation of PA protein and reduced suppression of PA on non-viral protein expression.Our study highlights the effects of PA-X on the moderation of viral pathogenesis and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, China.

ABSTRACT
PA-X is a novel protein encoded by PA mRNA and is found to decrease the pathogenicity of pandemic 1918 H1N1 virus in mice. However, the importance of PA-X proteins in current epidemiologically important influenza A virus strains is not known. In this study, we report on the pathogenicity and pathological effects of PA-X deficient 2009 pandemic H1N1 (pH1N1) and highly pathogenic avian influenza H5N1 viruses. We found that loss of PA-X expression in pH1N1 and H5N1 viruses increased viral replication and apoptosis in A549 cells and increased virulence and host inflammatory response in mice. In addition, PA-X deficient pH1N1 and H5N1 viruses up-regulated PA mRNA and protein synthesis and increased viral polymerase activity. Loss of PA-X was also accompanied by accelerated nuclear accumulation of PA protein and reduced suppression of PA on non-viral protein expression. Our study highlights the effects of PA-X on the moderation of viral pathogenesis and pathogenicity.

Show MeSH

Related in: MedlinePlus

PA-X deficiency increased viral polymerase activity and expression of PA protein.Polymerase activities of PA-X deficient and wild type pH1N1 (A) and H5N1 (B) viruses are expressed as mean percentage activity ± SD, with corresponding wild-type PA set at 100% from three independent experiments. Western blot analysis to detect PA, PB1 and β-actin in protein lysates from 293T cells transfected with polymerase plasmids (C) and from MDCK cells infected with PA-X deficient and wild type viruses at 1.0 MOI for 12 h (D). The protein bands were quantified by densitometry. Relative protein levels of PA or PB1 as compared with β-actin are shown as histograms. Mock transfection and mock infection served as negative control. The samples of infection or transfection cells derived from the same experiment and the blots were processed in parallel. Full-length blots are presented in Supplementary Figure 2. MDCK cells and A549 cells (E) were infected with the indicated viruses at 1.0 MOI for 12 h. PA mRNA expression was normalized to NP mRNA expression of the same virus. * indicates significant difference between virus with PA-X deficient and corresponding wild type virus. Differences were considered statistically significant at P < 0.05. The values shown are means ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4317690&req=5

f6: PA-X deficiency increased viral polymerase activity and expression of PA protein.Polymerase activities of PA-X deficient and wild type pH1N1 (A) and H5N1 (B) viruses are expressed as mean percentage activity ± SD, with corresponding wild-type PA set at 100% from three independent experiments. Western blot analysis to detect PA, PB1 and β-actin in protein lysates from 293T cells transfected with polymerase plasmids (C) and from MDCK cells infected with PA-X deficient and wild type viruses at 1.0 MOI for 12 h (D). The protein bands were quantified by densitometry. Relative protein levels of PA or PB1 as compared with β-actin are shown as histograms. Mock transfection and mock infection served as negative control. The samples of infection or transfection cells derived from the same experiment and the blots were processed in parallel. Full-length blots are presented in Supplementary Figure 2. MDCK cells and A549 cells (E) were infected with the indicated viruses at 1.0 MOI for 12 h. PA mRNA expression was normalized to NP mRNA expression of the same virus. * indicates significant difference between virus with PA-X deficient and corresponding wild type virus. Differences were considered statistically significant at P < 0.05. The values shown are means ± SD.

Mentions: Ribonucleoprotein (RNP) polymerase activity has been shown to correlate with viral replication and pathogenicity2425. We used an influenza virus mini-genome assay in 293T cells to determine the effect of PA-X on corresponding viral polymerase activity26. The use of PA-X deficient pH1N1 and H5N1 viruses resulted in a 24% and 85% increase, respectively, of RNP activity relative to corresponding wild type viruses (P < 0.05) (Fig. 6A and B).


The contribution of PA-X to the virulence of pandemic 2009 H1N1 and highly pathogenic H5N1 avian influenza viruses.

Gao H, Sun Y, Hu J, Qi L, Wang J, Xiong X, Wang Y, He Q, Lin Y, Kong W, Seng LG, Sun H, Pu J, Chang KC, Liu X, Liu J - Sci Rep (2015)

PA-X deficiency increased viral polymerase activity and expression of PA protein.Polymerase activities of PA-X deficient and wild type pH1N1 (A) and H5N1 (B) viruses are expressed as mean percentage activity ± SD, with corresponding wild-type PA set at 100% from three independent experiments. Western blot analysis to detect PA, PB1 and β-actin in protein lysates from 293T cells transfected with polymerase plasmids (C) and from MDCK cells infected with PA-X deficient and wild type viruses at 1.0 MOI for 12 h (D). The protein bands were quantified by densitometry. Relative protein levels of PA or PB1 as compared with β-actin are shown as histograms. Mock transfection and mock infection served as negative control. The samples of infection or transfection cells derived from the same experiment and the blots were processed in parallel. Full-length blots are presented in Supplementary Figure 2. MDCK cells and A549 cells (E) were infected with the indicated viruses at 1.0 MOI for 12 h. PA mRNA expression was normalized to NP mRNA expression of the same virus. * indicates significant difference between virus with PA-X deficient and corresponding wild type virus. Differences were considered statistically significant at P < 0.05. The values shown are means ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4317690&req=5

f6: PA-X deficiency increased viral polymerase activity and expression of PA protein.Polymerase activities of PA-X deficient and wild type pH1N1 (A) and H5N1 (B) viruses are expressed as mean percentage activity ± SD, with corresponding wild-type PA set at 100% from three independent experiments. Western blot analysis to detect PA, PB1 and β-actin in protein lysates from 293T cells transfected with polymerase plasmids (C) and from MDCK cells infected with PA-X deficient and wild type viruses at 1.0 MOI for 12 h (D). The protein bands were quantified by densitometry. Relative protein levels of PA or PB1 as compared with β-actin are shown as histograms. Mock transfection and mock infection served as negative control. The samples of infection or transfection cells derived from the same experiment and the blots were processed in parallel. Full-length blots are presented in Supplementary Figure 2. MDCK cells and A549 cells (E) were infected with the indicated viruses at 1.0 MOI for 12 h. PA mRNA expression was normalized to NP mRNA expression of the same virus. * indicates significant difference between virus with PA-X deficient and corresponding wild type virus. Differences were considered statistically significant at P < 0.05. The values shown are means ± SD.
Mentions: Ribonucleoprotein (RNP) polymerase activity has been shown to correlate with viral replication and pathogenicity2425. We used an influenza virus mini-genome assay in 293T cells to determine the effect of PA-X on corresponding viral polymerase activity26. The use of PA-X deficient pH1N1 and H5N1 viruses resulted in a 24% and 85% increase, respectively, of RNP activity relative to corresponding wild type viruses (P < 0.05) (Fig. 6A and B).

Bottom Line: In this study, we report on the pathogenicity and pathological effects of PA-X deficient 2009 pandemic H1N1 (pH1N1) and highly pathogenic avian influenza H5N1 viruses.Loss of PA-X was also accompanied by accelerated nuclear accumulation of PA protein and reduced suppression of PA on non-viral protein expression.Our study highlights the effects of PA-X on the moderation of viral pathogenesis and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, China.

ABSTRACT
PA-X is a novel protein encoded by PA mRNA and is found to decrease the pathogenicity of pandemic 1918 H1N1 virus in mice. However, the importance of PA-X proteins in current epidemiologically important influenza A virus strains is not known. In this study, we report on the pathogenicity and pathological effects of PA-X deficient 2009 pandemic H1N1 (pH1N1) and highly pathogenic avian influenza H5N1 viruses. We found that loss of PA-X expression in pH1N1 and H5N1 viruses increased viral replication and apoptosis in A549 cells and increased virulence and host inflammatory response in mice. In addition, PA-X deficient pH1N1 and H5N1 viruses up-regulated PA mRNA and protein synthesis and increased viral polymerase activity. Loss of PA-X was also accompanied by accelerated nuclear accumulation of PA protein and reduced suppression of PA on non-viral protein expression. Our study highlights the effects of PA-X on the moderation of viral pathogenesis and pathogenicity.

Show MeSH
Related in: MedlinePlus