J Infect Dis. Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Path

[Giuseppe]

Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus. (J Infect Dis., abstract, edited)

12. J Infect Dis. 2010 Apr 1;201(7):993-9.

Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus.

van den Brand JM, Stittelaar KJ, van Amerongen G, Rimmelzwaan GF, Simon J, de Wit E, Munster V, Bestebroer T, Fouchier RA, Kuiken T, Osterhaus AD. - Department of Virology, Erasmus Medical Centre and 2ViroClinics Biosciences BV, Rotterdam, The Netherlands.

Background.
The newly emerged influenza A(H1N1) virus (new H1N1 virus) is causing the first influenza pandemic of this century. Three influenza pandemics of the previous century caused variable mortality, which largely depended on the development of severe pneumonia. However, the ability of the new H1N1 virus to cause pneumonia is poorly understood.

Methods.
The new H1N1 virus was inoculated intratracheally into ferrets. Its ability to cause pneumonia was compared with that of seasonal influenza H1N1 virus and highly pathogenic avian influenza (HPAI) H5N1 virus by using clinical, virological, and pathological analyses.

Results.
Our results showed that the new H1N1 virus causes pneumonia in ferrets intermediate in severity between that caused by seasonal H1N1 virus and by HPAI H5N1 virus. The new H1N1 virus replicated well throughout the lower respiratory tract and more extensively than did both seasonal H1N1 virus (which replicated mainly in the bronchi) and HPAI H5N1 virus (which replicated mainly in the alveoli). High loads of new H1N1 virus in lung tissue were associated with diffuse alveolar damage and mortality.

Conclusions.
The new H1N1 virus may be intrinsically more pathogenic for humans than is seasonal H1N1 virus.

PMID: 20187747 [PubMed - in process]
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[kent nickell]

Re: J Infect Dis. Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus.

bumped for emphasis...

"""The new H1N1 virus replicated well throughout the lower respiratory tract and more extensively than did both seasonal H1N1 virus (which replicated mainly in the bronchi) and HPAI H5N1 virus (which replicated mainly in the alveoli). High loads of new H1N1 virus in lung tissue were associated with diffuse alveolar damage and mortality.

Conclusions.
The new H1N1 virus may be intrinsically more pathogenic for humans than is seasonal H1N1 virus."""

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also

http://www.sciencedirect.com/scienc...serid=10&md5=c681faab7e7b1804351b3dbad11a345e

Archives of Medical Research
Volume 40, Issue 8, November 2009, Pages 655-661

Comparison of the Pathology Caused by H1N1, H5N1, and H3N2 Influenza Viruses

Jeannette Guarnera, , and Reynaldo Falc?n-Escobedob

a Department of Pathology and Laboratory Medicine, Emory University Hospital, Atlanta, Georgia

b Department of Pathology, Hospital Central Dr. Ignacio Morones Prieto, San Luis Potosi, Mexico

Received 8 September 2009;
accepted 21 September 2009.
Available online 6 January 2010.

excerpt:

Localization of the inflammation and cellular damage relate to the presence of virus in different cell types. Infections with 1918 H1N1, the novel 2009 H1N1 pandemic virus, and H5N1 show virus in mucosal epithelial cells of the airways (from the nasopharynx to the bronchioles), alveolar macrophages, and pneumocytes, whereas infections with seasonal influenza viruses show viral antigens primarily in mucosal epithelial cells of the larger airways. The increased morbidity that has been encountered with the 2009 H1N1 virus is related to infection of cells in the upper and lower airways. The 2009 H1N1 virus shows similar pathology to that encountered with other highly virulent influenza A viruses such as the 1918 H1N1 and H5N1 viruses.

 

[sharon sanders]

Re: J Infect Dis. Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus.

Thanks Kent -

Actual Pathology Notes from an A/H1N1 Autopsy - Lung Damage Caused H1N1 Swine Flu Death

"...I will just go to the heart of it. And that's to do with the lungs. There was a little bit of straw-colored fluid around the lungs in the chest cavity, which is a non-specific finding, but when the doctor who I was supervising doing to case was looking at the airways, the trachea and the bronchi, and they were really red, like tomato, beetroot red. They are normally a light-pink color, so clearly inflamed. And this was all the way down the bronchiole tree.

People who die of bronchi pneumonia or standard pneumonia, you will often see pus in the airways, but there was no pus in this guy's airways, just intensely red.

The histology of the airways showed a lot of epithelial ulceration. A loss of the surface lining cells with obviously bleeding underneath, which I think partly explains why he was coughing up blood. And acute inflammation of the upper air passages -- the trachea and the main bronchi. But not of the sort that looks like acute bronchitis with neutrophils. Neutrophils are what's colloquially called pus cells. And if you have got acute bronchitis from say a bacteria like staph. or something like that, they are the first line of defense cells that go and gobble up the bacteria.

In this particular case, there were hardly any neutrophils because it's not a bacterial infection, it's a viral infection.

Not much evidence of a secondary bacterial infection at all.

Which is a little surprising, but that’s what we saw. There were hardly any neutrophils. There were some floating around, but the main cells were lymphocytes which are more to do with chronic inflammation and viral infections as well. And other forms of acute inflammatory cells as well called eosinophils and they named that because of the intense orange color of the cytoplasm of the cells when you stain them with a particular stain.

But their function is more related to allergy. So if you see a lot of eosinophils in lungs in particular, you might think of asthma or some allergic phenomenon that's attracting those eosinophils to that site. I am not suggesting for a minute that this was an allergic phenomenon at all. This was a viral-type process. For whatever reason, and I don’t understand it, those sorts of cells -- the eosinophils and the lymphocytes were being attracted to that inflammatory area.

That was the first thing -- so intense inflammation of the upper air passages. The lungs were heavy. They were about twice to three times as heavy (as normal). ..."


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