H7N9 flu virus differs from other viruses

[tetano]

Japanese researchers say the new strain of influenza virus spreading in China has different characteristics than other avian viruses. They are calling for the development of a new vaccine.

Experts at the National Institute of Infectious Diseases released their findings on Thursday. Their findings are based on gene sequences obtained from China of 2 Shanghai men who died from the infection and an Anhui Province woman in serious condition.

They say that H7N9 influenza viruses likely infect cells inside human nose, throat and upper part of the respiratory tract. The viruses can multiply easily in those environs. They say most bird flu viruses grow inside the lungs.

Its gene arrangement shows the effect on birds is low. But the researchers say they have yet to find out why the virus causes serious pneumonia and other severe symptoms in humans.

The head of the team of influenza experts at the institute, Takato Odagiri, warns that existing influenza vaccines will not work judging from the virus's gene sequences. He calls for the development of new vaccines as well as the stepping up of research into animals as the origin of the new infections.

http://www3.nhk.or.jp/nhkworld/english/news/20130405_02.html

 

[Giuseppe]

Re: H7N9 flu virus differs from other viruses

H5N1 underwent several changes since its first emersion in 1997 HK outbreak and epizootics.

Some clusters of cases happened in Turkey, Indonesia, Pakistan, China. Sometimes human samples from these clusters carried viruses with some mutations like those indicated in the above article.

H5N1 isolates demonstrated better affinity with human upper airway epithelium (mixed avian/human receptor binding affinity) and a polymerase basic sub-unit mutation permitting the virus to replicate at a body temperature lower than in birds (ie. 37?C, the human internal body temperature).

Notwithstanding these mutation, H5N1 was never able to sustain a human-to-human transmission in community settings.

It is clear that if H7N9 will be confirmed to be able to do this, well other changes would be responsibile for this adaptation.

Our understanding of influenza virus ecology is not so perfect to state with certainty that - on the basis of the genetic marker signatures alone - a pathogen could do a thing instead of another.

For this reason, a clear, honest and timely reporting of cases from the field are unvaluable for a public health perspective.

This, is true also for all information about clinical course, histopathology changes and treatment failures.

GM

 

[NS1]

Re: H7N9 flu virus differs from other viruses

We are grateful to the samplers, the depositing labs and the GISAID consortium for making the small batch of evaluation material available on 2013-03-31 during this zoonotic epidemic emergence of H7N9 that has the very unfortunate combination of a High Case Fatality Rate and Low clinical intervention effectiveness [GISAID Citations].

The H7N9 human cases show clinically and experimentally-confirmed Gain of Function traits on a minimum of 3 gene segments:

• Hemagglutinin 226L
• Neuraminidase aa69-73 stalk deletion (15 base)
• Polymerase Basic 2 627K

The H7N9 sequences are related at the polymorphism level to widely circulating human virus patterns including pH1N1, sH3N2 and to fatal human H5N1. Each component of the H7N9 human cases carries sub-segment genetics that have seen mammalian adaptation, including the external proteins, Hemagglutinin and Neuraminidase.

An up-to-date and comprehensive follow-up evaluation for each HA polymorphism found on the 3 human H7N9 sequences was provided Wednesday, 2013-04-03, demonstrating the Cross Serotype Homology details. The preliminary H7N9 Novelty Evaluation and Relationship Potential to pH1N1 with detailed Hemagglutinin amino-level polymorphism surfacing was made available for preview on 2013-03-31, formalised at midnight and is now being versioned.

Genetic specifics concerning animal origins and human / mammal adaption are under analysis. The full text of those intermediate reports are currently in pre-publication viewing status and are available at the following links. These compilations will be updated as labs release new sequences.

• GeneWurx Human Emergent H7N9 Cross Serotype Homology (External Genes)
• GeneWurx Human Emergent H7N9 Rare and Novel Hemagglutinin Antigens (External Genes)
• GeneWurx Human Emergent H7N9 ReAssortment Assessment (Internal Genes)

Additional sequences from early emergence fatal and recovered cases are critical to understanding the immune dynamics required for establishing a bulkhead toward the protection of public health.