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Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences in general acute responses.

Rebel JM, Peeters B, Fijten H, Post J, Cornelissen J, Vervelde L - Vet. Res. (2011)

Bottom Line: No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found.In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus.However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8α+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs.A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.

View Article: PubMed Central - HTML - PubMed

Affiliation: Central Veterinary Institute, PO box 65, 8219 PH Lelystad, The Netherlands. Annemarie.Rebel@WUR.nl.

ABSTRACT
Avian influenza virus can be divided into two groups, highly pathogenic avian influenza virus (HPAI) and low pathogenic avian influenza virus (LPAI) based on their difference in virulence. To investigate if the difference in clinical outcome between LPAI and HPAI in chickens is due to immunological host responses in the lung within the first 24 hours post infection (hpi), chickens were infected with LPAI or HPAI of subtype H7N1. Virus was found in the caudal and cranial part of the lung. With LPAI, virus was localised around the intrapulmonary bronchus and secondary bronchi. In sharp contrast, HPAI was detected throughout the whole lung. However, based on viral RNA levels, no quantitative difference was observed between LPAI and HPAI infected birds. In infected areas of the lungs, an influx of CD8α+ cells as well as KUL01+ macrophages and dendritic cells (DC) occurred as fast as 8 hpi in both infected groups. No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found.In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus. However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8α+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs. A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.

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Pro-inflammatory cytokine mRNA expression in the cranial and caudal part of the lung after inoculation with LPAI (white bar) or HPAI (black bar) at different time points post inoculation (hpi). IL-1β, IL-6 and IL-8 mRNA expression was shown as fold induction compared to uninfected birds ± SD. * p < 0.05 between infected and control chickens; line p < 0.05 between the LPAI and HPAI group of a specific time point pi.
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Figure 5: Pro-inflammatory cytokine mRNA expression in the cranial and caudal part of the lung after inoculation with LPAI (white bar) or HPAI (black bar) at different time points post inoculation (hpi). IL-1β, IL-6 and IL-8 mRNA expression was shown as fold induction compared to uninfected birds ± SD. * p < 0.05 between infected and control chickens; line p < 0.05 between the LPAI and HPAI group of a specific time point pi.

Mentions: The amounts of pro-inflammatory cytokines and interferons were examined by measuring mRNA levels in the lung (Figure 5 and 6). In the caudal parts of the lung IL-1β, IL-6 and IL-8 mRNA was upregulated compared to uninfected birds, while in the cranial part only induction of IL-8 mRNA was observed. In HPAI infected birds, the mRNA expression seemed to peak at 16 hpi, whereas for the LPAI infected birds highest expression was detected at 24 hpi. The only significant difference (P = 0.06) between LPAI and HPAI infection was a higher IL-8 mRNA induction in the cranial part of the LPAI infected birds (45.5 fold induction in the LPAI group and 3.4 fold induction in the HPAI group).


Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences in general acute responses.

Rebel JM, Peeters B, Fijten H, Post J, Cornelissen J, Vervelde L - Vet. Res. (2011)

Pro-inflammatory cytokine mRNA expression in the cranial and caudal part of the lung after inoculation with LPAI (white bar) or HPAI (black bar) at different time points post inoculation (hpi). IL-1β, IL-6 and IL-8 mRNA expression was shown as fold induction compared to uninfected birds ± SD. * p < 0.05 between infected and control chickens; line p < 0.05 between the LPAI and HPAI group of a specific time point pi.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3037890&req=5

Figure 5: Pro-inflammatory cytokine mRNA expression in the cranial and caudal part of the lung after inoculation with LPAI (white bar) or HPAI (black bar) at different time points post inoculation (hpi). IL-1β, IL-6 and IL-8 mRNA expression was shown as fold induction compared to uninfected birds ± SD. * p < 0.05 between infected and control chickens; line p < 0.05 between the LPAI and HPAI group of a specific time point pi.
Mentions: The amounts of pro-inflammatory cytokines and interferons were examined by measuring mRNA levels in the lung (Figure 5 and 6). In the caudal parts of the lung IL-1β, IL-6 and IL-8 mRNA was upregulated compared to uninfected birds, while in the cranial part only induction of IL-8 mRNA was observed. In HPAI infected birds, the mRNA expression seemed to peak at 16 hpi, whereas for the LPAI infected birds highest expression was detected at 24 hpi. The only significant difference (P = 0.06) between LPAI and HPAI infection was a higher IL-8 mRNA induction in the cranial part of the LPAI infected birds (45.5 fold induction in the LPAI group and 3.4 fold induction in the HPAI group).

Bottom Line: No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found.In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus.However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8α+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs.A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.

View Article: PubMed Central - HTML - PubMed

Affiliation: Central Veterinary Institute, PO box 65, 8219 PH Lelystad, The Netherlands. Annemarie.Rebel@WUR.nl.

ABSTRACT
Avian influenza virus can be divided into two groups, highly pathogenic avian influenza virus (HPAI) and low pathogenic avian influenza virus (LPAI) based on their difference in virulence. To investigate if the difference in clinical outcome between LPAI and HPAI in chickens is due to immunological host responses in the lung within the first 24 hours post infection (hpi), chickens were infected with LPAI or HPAI of subtype H7N1. Virus was found in the caudal and cranial part of the lung. With LPAI, virus was localised around the intrapulmonary bronchus and secondary bronchi. In sharp contrast, HPAI was detected throughout the whole lung. However, based on viral RNA levels, no quantitative difference was observed between LPAI and HPAI infected birds. In infected areas of the lungs, an influx of CD8α+ cells as well as KUL01+ macrophages and dendritic cells (DC) occurred as fast as 8 hpi in both infected groups. No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found.In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus. However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8α+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs. A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.

Show MeSH
Related in: MedlinePlus