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Additional Evidence That the Polymerase Subunits Contribute to the Viral Replication and the Virulence of H5N1 Avian Influenza Virus Isolates in Mice.

Qu X, Ding L, Qin Z, Wu J, Pan Z - PLoS ONE (2015)

Bottom Line: In mammalian cells, HN05 replicates more efficiently than HB04, although both viruses have similar growth kinetics in avian cells.HN05 genes encoding the polymerase complex determine pathogenicity and viral replication ability both in vitro and in vivo.These results can be used to elucidate host-range expansion and the molecular basis of the high virulence of H5N1 viruses in mammalian species.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.

ABSTRACT
Genetically similar H5N1 viruses circulating in the avian reservoir exhibit different levels of pathogenicity in mice. In this study, we characterized two highly pathogenic H5N1 avian isolates--A/Hunan/316/2005 (HN05), which is highly pathogenic in mice, and A/Hubei/489/2004 (HB04), which is nonpathogenic. In mammalian cells, HN05 replicates more efficiently than HB04, although both viruses have similar growth kinetics in avian cells. We used reverse genetics to generate recombinant H5N1 strains containing genes from HN05 and HB04 and examined their virulence. HN05 genes encoding the polymerase complex determine pathogenicity and viral replication ability both in vitro and in vivo. The PB2 subunit plays an important role in enhancing viral replication, and the PB1 and PA subunits contribute mainly to pathogenicity in mice. These results can be used to elucidate host-range expansion and the molecular basis of the high virulence of H5N1 viruses in mammalian species.

No MeSH data available.


Related in: MedlinePlus

Replication in vivo and pathogenicity of recombinant viruses containing swapped polymerase genes in mice.(A) Six-week-old female BALB/c mice (n = 15) were infected intranasally with 2×103 TCID50 of recombinant viruses. At the indicated time points, the infected mice (n = 5) were euthanized, and the viral titers in lungs were determined using MDCK cells (*, p<0.01). (B) Representative histopathological changes in H&E-stained lung tissues from mice infected with recombinant viruses at 5 dpi (20×).
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pone.0124422.g005: Replication in vivo and pathogenicity of recombinant viruses containing swapped polymerase genes in mice.(A) Six-week-old female BALB/c mice (n = 15) were infected intranasally with 2×103 TCID50 of recombinant viruses. At the indicated time points, the infected mice (n = 5) were euthanized, and the viral titers in lungs were determined using MDCK cells (*, p<0.01). (B) Representative histopathological changes in H&E-stained lung tissues from mice infected with recombinant viruses at 5 dpi (20×).

Mentions: To examine the replication of recombinants containing swapped polymerase genes in vivo, we measured viral titers in the lungs of mice infected with the reassortant virus rHB/HN-Pol, rHB/HN-PB2, rHB/HN-PB1, rHB/HN-PA, or rHB/HN-NP at 1, 3 and 5 dpi, respectively. We observed that the rHB/HN-Pol viral titers in the lungs were higher than any single-gene reassortant at 1 or 3 dpi (p<0.01). However, at 5 dpi, the rHB/HN-PB2 viral titer in the lungs of infected mice was similar to that of the rHB/HN-Pol virus; the rHB/HN-NP virus was not detected in the lungs of infected mice. The rHB/HN-PB1 and rHB/HN-PA viral titers were lower at 5 dpi than at 3 dpi (Fig 5A). To examine the relationship between pathogenicity and viral replication ability in vivo, the lung tissues of infected mice were analyzed by H&E staining at 5 dpi. Mice infected with rHB/HN-Pol had severe lung pathology including increased inflammatory infiltrates and hypertrophy of the alveolar lining cells, whereas mice infected with rHB/HN-NP had much less severe lung pathology. The severity of the lung pathology of mice infected with the single polymerase gene reassortants decreased in the following order: rHB/HN-PB1> rHB/HN-PB2> rHB/HN-PA. As expected, no histopathological change was observed in the PBS control mice (Fig 5B).


Additional Evidence That the Polymerase Subunits Contribute to the Viral Replication and the Virulence of H5N1 Avian Influenza Virus Isolates in Mice.

Qu X, Ding L, Qin Z, Wu J, Pan Z - PLoS ONE (2015)

Replication in vivo and pathogenicity of recombinant viruses containing swapped polymerase genes in mice.(A) Six-week-old female BALB/c mice (n = 15) were infected intranasally with 2×103 TCID50 of recombinant viruses. At the indicated time points, the infected mice (n = 5) were euthanized, and the viral titers in lungs were determined using MDCK cells (*, p<0.01). (B) Representative histopathological changes in H&E-stained lung tissues from mice infected with recombinant viruses at 5 dpi (20×).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418698&req=5

pone.0124422.g005: Replication in vivo and pathogenicity of recombinant viruses containing swapped polymerase genes in mice.(A) Six-week-old female BALB/c mice (n = 15) were infected intranasally with 2×103 TCID50 of recombinant viruses. At the indicated time points, the infected mice (n = 5) were euthanized, and the viral titers in lungs were determined using MDCK cells (*, p<0.01). (B) Representative histopathological changes in H&E-stained lung tissues from mice infected with recombinant viruses at 5 dpi (20×).
Mentions: To examine the replication of recombinants containing swapped polymerase genes in vivo, we measured viral titers in the lungs of mice infected with the reassortant virus rHB/HN-Pol, rHB/HN-PB2, rHB/HN-PB1, rHB/HN-PA, or rHB/HN-NP at 1, 3 and 5 dpi, respectively. We observed that the rHB/HN-Pol viral titers in the lungs were higher than any single-gene reassortant at 1 or 3 dpi (p<0.01). However, at 5 dpi, the rHB/HN-PB2 viral titer in the lungs of infected mice was similar to that of the rHB/HN-Pol virus; the rHB/HN-NP virus was not detected in the lungs of infected mice. The rHB/HN-PB1 and rHB/HN-PA viral titers were lower at 5 dpi than at 3 dpi (Fig 5A). To examine the relationship between pathogenicity and viral replication ability in vivo, the lung tissues of infected mice were analyzed by H&E staining at 5 dpi. Mice infected with rHB/HN-Pol had severe lung pathology including increased inflammatory infiltrates and hypertrophy of the alveolar lining cells, whereas mice infected with rHB/HN-NP had much less severe lung pathology. The severity of the lung pathology of mice infected with the single polymerase gene reassortants decreased in the following order: rHB/HN-PB1> rHB/HN-PB2> rHB/HN-PA. As expected, no histopathological change was observed in the PBS control mice (Fig 5B).

Bottom Line: In mammalian cells, HN05 replicates more efficiently than HB04, although both viruses have similar growth kinetics in avian cells.HN05 genes encoding the polymerase complex determine pathogenicity and viral replication ability both in vitro and in vivo.These results can be used to elucidate host-range expansion and the molecular basis of the high virulence of H5N1 viruses in mammalian species.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.

ABSTRACT
Genetically similar H5N1 viruses circulating in the avian reservoir exhibit different levels of pathogenicity in mice. In this study, we characterized two highly pathogenic H5N1 avian isolates--A/Hunan/316/2005 (HN05), which is highly pathogenic in mice, and A/Hubei/489/2004 (HB04), which is nonpathogenic. In mammalian cells, HN05 replicates more efficiently than HB04, although both viruses have similar growth kinetics in avian cells. We used reverse genetics to generate recombinant H5N1 strains containing genes from HN05 and HB04 and examined their virulence. HN05 genes encoding the polymerase complex determine pathogenicity and viral replication ability both in vitro and in vivo. The PB2 subunit plays an important role in enhancing viral replication, and the PB1 and PA subunits contribute mainly to pathogenicity in mice. These results can be used to elucidate host-range expansion and the molecular basis of the high virulence of H5N1 viruses in mammalian species.

No MeSH data available.


Related in: MedlinePlus